The Ultimate Seed Starting Guide to planning, starting and successfully growing your own food. Never ask again why did my seedlings die? What seeds should I start? When should I start my seeds indoors? Do I have to have a grow light?
Seriously, when done right, seed starting can be an amazing way to increase the number of crops you can grow and your growing season, but not all seeds should be started indoors and there are many mistakes that can easily be avoided if you simply know ahead of time. That my friends is where I come in because I want you to harvest bushels of food this year.
This is an updated episode of the Pioneering Today Podcast on seed starting (Episode #291 – but you can still listen to the older podcast, Episode #130, below)
Seed Starting vs. Direct Sowing
What is the difference between starting seeds indoors and direct sowing seeds? In short, seed starting inside is where you germinate your seeds inside in a controlled environment, then transplant the young plants into the garden. Direct sowing seeds is done outside, where you plant the seeds directly into the soil where the plant will grow and live its entire life.
Why Start Seeds Indoors?
When you start seeds indoors you have more variety. If you're buying plant starts from a nursery, you're left to choose from the varieties they offer. But when you start from seed, you have so many more options.
You also are able to have a controlled environment for your seedlings. Sometimes plants that aren't as hardy do better when started indoors.
Which Seeds Should I Start Indoors?
Most root vegetables are better off being direct sown outdoors. The only root vegetable I actually start indoors is onions. Because I don’t want to buy onion sets from the nursery, so I grow my own.
Cool-weather crops like lettuce, spinach, and other brassicas don't need to be started indoors as they can handle the cooler temperatures of the soil.
However warm-weather crops such as peppers, tomatoes, cucumbers, even melons, and some squash do really well when started indoors.
The seeds you start indoors will depend upon your zone and window of warm weather. If you have a really long growing period, then you may be able to direct sow all of your plants. If you live in the Pacific Northwest, like me, you'll need to start some of your plants indoors in order to even get a harvest.
When to Start Seeds Indoors
Seeds always germinate better when they’re outside getting direct sunlight. But if the temperatures aren’t right yet, this is why we start them inside.
You don't want to start your seeds too soon or too late (it’s kind of like Goldilocks, finding the perfect time for your garden). This start date is always dependent on when your last frost is in the Spring and when your first frost is in the fall.
Once you know your first frost date (both my books, The Family Garden Plan or The Family Garden Planner have charts to help with this planning), you can count backward based on the number of weeks you should start those plants indoors to know when to get them going.
- Onions – If you want to start onions from seeds and not purchase onion sets, you'll need to start them first, 10 weeks before your last average frost date.
- Peppers and tomatoes are about 4 to 8 weeks before your last average frost, if you live where it's cooler, I recommend 8 weeks.
It's important to note that even with knowing your gardening zone and the general rule of thumb on your first and last average frost dates, there are always micro-climates in regions. I recommend asking around to your neighbors to get the best idea.
For example: According to the data I'm in gardening zone 7B and my last average frost date is April 29th and the first average frost date is October 14th (click here to find yours by your zip code).
But, I live up in the foothills and we have more extreme temperatures, which means we'll have a sneak frost sometimes come in as early as September 20th and we never plant our warm weather plants out in the spring until May 20th or later (depending upon the weather that year).
We usually don’t plant until 1-2 weeks AFTER your last frost date because, typically speaking, your soil temperature is about 10 degrees cooler than the temperature outside.
Talk to local gardeners in your area to find out when they plant, but the average frost dates and gardening zone give you a good rule of thumb.
What is Needed to Start Seeds Indoors
To successfully germinate and grow seeds indoors you'll need the proper combination of a few things:
- Seeds (Where to Buy Heirloom Seeds & My Favorite Seed Companies)
Choosing The Right Soil
Young plants are just like infants, they're more susceptible to disease and getting sick. If you use dirt straight from your garden you're introducing any disease, bacteria, or fungus that's in that soil to a baby without an immune system.
This is often the cause of dampening off (a form of blight on seedlings) one of the biggest culprits of why seedlings die.
You're also bringing insects and their eggs into the house or gardening shed. Which you don't want on your baby seedlings or flying and crawling about your living room (which is where I seed start).
How to choose the right soil:
- Purchase potting soil. I only use organic potting soil, it's already at the perfect mix and has been sterilized to kill any disease and/or fungus.
- Bake your dirt at 200 degrees until it reaches 180 internally. This is your at home version but I'll be honest, I don't want to deal with trays and trays of dirt in my oven.
- Make a mix of equal parts compost, top soil, and sand. Again, you'll need to sterilize it, but this is a DIY homemade way of making your own.
Seed Starting Containers
Too often people want to germinate their seeds in a larger pot so they don't have to transplant their seedlings into a larger pot before moving outdoors. However, seeds germinate best under a controlled environment and it's much easier to control the soil temperature of a small container of soil than if it's a big deep container.
I like to use plastic clamshell egg cartons because the holes are nice and small, plus when I close the lid the container acts like a natural greenhouse keeping the moisture and heat in.
Whether you repurpose an egg carton or buy the seed starting pods, you'll want to be sure there's a way to cover the container until germination is complete. For more seed starting containers, ideas and suggestions read What Are the Best Seed Starting Containers
Heat & Soil Temperature
The big question I get asked all the time is whether or not people need to buy seed starting mats in order to successfully start plants indoors. In my experience, the answer is no.
Even with my house temperatures dipping down in the mid to low 60’s at night, I’ve never actually needed to use a seedling mat to successfully germinate seeds. However, if your house (or where you’re starting your seeds) tends to be on the cooler side, a seed starting mat may be necessary.
Each seed has a unique temperature for germination, so check your seed packets to know how warm your soil temps need to be.
For warm-weather crops, your soil must be at least 60 degrees Fahrenheit or warmer for the seeds to germinate. The general rule of thumb is between 60 to 70 degrees, though your hot peppers may need to be 75+ for best germination rates.
You can use a soil thermometer or go by the average temperature in your home. I don't use seedling mats or hot pads and the temperature in our living room is usually 65 to 75 degrees (cooler in the early morning before the fire is built back up) and I haven't had an ounce of a problem getting my seeds to germinate.
Once seeds have sprouted, you want to make sure the overnight lows of the plants don't get below 50 degrees. So if your seedlings are sitting by a windowsill, you’ll want to move them away from the window overnight so they don’t get too cold by the window.
This is where people often get into trouble. When both germinating seeds and watering your seedlings once they've sprouted you don’t want the soil to be soaking wet, but you also don’t want the soil to get too dry.
Watering for Germination
It's important to keep the soil consistently damp for the first 10+ days until the seeds have germinated. To keep the soil damp it’s best to use a container that can create a greenhouse-like environment. This is why I like to use the plastic egg clamshell containers!
Depending on the seed, they typically take between 7-14 days to germinate. The closer you can get to the proper soil temperature and consistent moisture, the faster they’ll germinate.
You don’t want the soil to continue to stay damp like you do when seeds are germinating, otherwise, you’ll get rot and you may see some mold.
It’s a good idea to allow the top surface of the soil to dry out between waterings because this forces the roots to go down in search of water.
I like to test the soil simply by touching it with my finger or pulling back the top layer of soil to make sure the soil is damp underneath.
Plants don’t actually need sunlight when they’re germinating, so you don’t need to have a sunny windowsill, or grow lights on during the first week or two. However, once they've germinated you have two options for light:
- Sunny windowsill
- Grow light
For most people, especially if you live in a northern climate, a sunny windowsill will not provide enough hours of daylight for your plants. You'll need 6 to 8 hours of direct sunlight for plants a day.
When using artificial light you also want to be sure the lightbulb is full-spectrum. Because it’s not as strong as the actual sun, you're going to need to leave the lights on for 16 to 18 hours every day. I turn mine on when I get up, first thing in the morning, and off when I go to bed.
I've had this same grow light for six years, including the same bulbs click here for my favorite grow light.
Proximity of Plants to Light
When using artificial light to grow your seedlings, it needs to be within 2-3 inches above the plant. Leggy and tall plants occur when plants aren’t getting enough light, so they’re stretching to reach the light source.
Most people don’t give their plants enough light because they read the seed packets which tell you the plants need 6-8 hours a day, but that’s full sunlight during the middle of summer, not an artificial light bulb.
How to Start Seeds Indoors
- Once you have all the materials needed, you'll want to fill your containers about 2/3 full with potting soil.
- Place 2-3 seeds per pot on top of the soil. A general rule of thumb is to plant twice as deep as the seed is wide. I find for smaller seeds when I water, this pushes the seeds under the soil just enough.
- Add a small layer of soil over the seeds, if needed to be sure all seeds are covered.
- Mist soil with a spray bottle filled with warm water.
- Cover the container.
- Water 1-2 times daily for 7-10 days, keeping the soil consistently moist until seeds germinate.
I made you a video here on How to Start Tomato Seeds Indoors:
If you happen to have some really old seed packets and you're not sure if the seeds are viable (meaning you're not sure if they'll actually grow), you can do a paper towel germination test.
This test isn't actually for germinating plants, but just to test the viability of your seeds.
To test your seeds:
- Take a damp paper towel and place 5-10 seeds on top.
- Cover the seeds with another damp paper towel.
- Keep the paper towel damp for 5-7 days, checking every few days to see how many of the seeds germinate.
This will give you a good indication of how many seeds you should sow in order to get the number of plants you want.
For example, if you want to grow 10 tomato plants in your garden, it’s not a good idea to only plant 10 tomato seeds. Seeds are very inexpensive, so it’s always better to plant more seeds (double or triple) than you’ll need. That way you can keep the best, most robust-looking seedlings and give away what you don't need.
Caring for Plant Starts Indoors
Continue to give your plants adequate light and water for the duration of their life. Even once transplanted outdoors, you'll want to be sure they're planted in a location where they'll get enough sunlight.
After four weeks of growing, your plants will need additional care such as feedings, toughening up, and eventually hardening off before transplanting outdoors.
Feeding Your Plants
Once your seeds have germinated you will see the first set of leaves, these aren’t actually their “true” leaves. These tiny leaves actually contain nutrition from the seed that feeds the seedling until the roots are big and strong enough to get nutrients from the soil (about the first 4 weeks).
The second set of leaves that appear are the plant’s “true” leaves and they will actually resemble the leaves of the mature plant.
Once these “true” leaves appear it’s critical to get the plants under a grow light and make sure the plant has enough nutrients (if you used an all-purpose potting soil, it’s likely your plants will have what they need for the first 4 weeks).
At 4 weeks you’ll want to start feeding your plants a bit of fertilizer. To do this I mix together some fish fertilizer with my water and water with it every week or even every other week to make sure the plants have enough nutrition.
Many people start seeds indoors but when they go to plant them outdoors they die. There are two reasons for this, you haven't hardened off your plants and you haven't toughened up your plants.
We'll cover hardening off next, but in nature, seedlings have rain hitting them, wind blowing around them, and they're constantly moving following the sun and being pushed around from airflow.
All of this helps the stem and the roots go deep. It develops a strong plant. Like working out, your muscles don't grow unless they're forced to work and move against something.
Mimic nature for your seedlings:
- You can place a fan on the plants periodically to mimic the wind.
- Run your hand over the leaves and the tops of the plant. This serves the same purpose as the fan but without the electricity and the fan. Whenever you walk by or turn on or off the light, run your hands over the plants.
- Use a spray bottle periodically to mimic rain. This also helps if you have low humidity in your area and means you don't have to water as often. I haven't experienced any negative effects, even doing this on my tomato plants.
Make sure your plants dry fully between misting sessions, as well as the top part of the soil, after the seedlings have sprouted (germinated) and have their first sets of leaves.
Hardening Off Your Plants
In order to transplant your plants into the garden, you need to go through a process of hardening off. If you don’t do this step, your plants will go into shock and die because they’re not ready for the large increase in temperature, the movement of the air, the strength of the sun, even the rain, etc.
This is where I see many people make the biggest mistake with their seedlings. They don't harden them off properly or for long enough.
In order to harden them off you want to pick a sheltered spot outdoors, starting somewhere that's not in direct hot sunlight and isn't out in the open where they'll be whipped by the wind and elements.
Seedling Hardening Off Schedule
Begin at least 1 week in advance before planting.
- Start in a protected area 2 hours the first day.
- Increase by 1 to 2 hours each day over 7 to 10 days.
- Gradually move them to their final planting spot (by the last 4 days of the hardening off schedule, I'll place the plants where I'll be planting them, which is in direct sunlight and without any wind protection).
Troubleshooting & FAQs
My plants are rootbound
If you start seeing the roots of your plants coming out the bottom of your container (or if you can see them at the bottom of the container), you’ll want to move your plants to a larger container.
Otherwise, your plants can become root-bound and they won't grow well once transplanted into the garden.
Why didn't my seeds germinate?
There are a few possibilities including incorrect soil temperature, not enough water, and seed viability. However, just because your seeds don’t sprout, it doesn’t necessarily mean you did something wrong.
Just as we discussed above, it could simply mean your seeds weren't viable. If you think at least some of the seeds should have germinated, you can do a seed germination test (directions above).
Otherwise, troubleshoot the soil temp and watering options and start again.
Why are my seedlings tall and spindly?
Plants will get tall and spindly from not getting enough light, if the light source is too far away, and if there isn't enough movement or stress on the plant.
If your plants are leggy, they're straining for more light and you need to deliver it as soon as possible to avoid week stemmed plants that will/can break when put outdoors.
Why are my leaves turning purple?
This happens often with tomato plants. If your leaves are turning purple they need more phosphorus, so the best course of action is to feed your plants with some fertilizer.
Why are my leaves turning yellow?
Yellow leaves are a sign of either not enough nitrogen or occasionally too much nitrogen, but the most common culprit is over watering which is depleting your soil of nitrogen. The best course of action is to feed your plants with some fertilizer.
Resources for Seed Starting at Home
- This is the 4-inch grow light I've used for over 6+ years (including the original bulb)!
- Fox Farm FX14053 12-Quart Ocean Forest Organic Potting Soil <– My favorite potting soil!
- Stainless Steel Soil Thermometer
More Articles to Get Your Garden Off to a Good Start:
- Beginner Gardening Secrets You Need to Know
- 13 Basic Steps to Starting a Vegetable Garden
- Gardening in March (Garden Tasks by Month)
- Time-Saving Tips For New Gardens
- Where to Buy Heirloom Seeds – Heirloom, Hybrid & GMO Differences
- Seed Packet Information – How to Read Seed Packets for Gardening Success
- Cold Stratification of Seeds – Why & How
- Best Way to Germinate Seeds – How to Germinate Seeds Faster
- What Are the Best Seed Starting Containers
- Potting Up Seedlings & How to Separate Seedlings
- Direct Sow Your Garden Seed
- Cut Back on Garden Diseases & Maximize Your Infrastructure Expansion (Don’t Waste Time or Money)
- Heirloom Seed Saving & Gardening
- How to Grow Food YEAR ROUND Using Covers (Hot & Cold Weather)
I have in-depth lessons covering seed starting, containers, hardening off, and transplanting in The Pioneering Today Academy.
Hey, pioneers. Welcome to episode number 291. Today's episode, I'm going to be sharing with you everything you need to know about how to start seeds indoors. Starting your seeds indoors seems to be one of the areas that I see a lot of confusion, or unfortunately a lot of failures. The good news is most of the issues that people have are the areas that are causing the failure. They're really, really simple to fix. They don't cost a lot of money to fix, and they can save you a lot of money in the long run. We've got a lot of things to cover in this episode. But you're going to have everything you need to know after you get done listening to it in order to successfully start your seeds indoors.
I'm really excited for this episode. One of the reasons is because at the time of this recording, it is in January and there's very little that I'm doing out in the garden in January. If we have a few breaks in the weather, I will do a little bit of pruning on the blueberries, but that's pretty much it and sometimes that doesn't even get to happen until February. But other than that, it's been a long time since I've had my hands in the dirt and actually get to tend to my plants. And so I get really excited for seed starting season to come, which for me... And we're going to talk about why my seed starting dates and your seed starting dates will likely be different and why you need to know when you should be starting your seeds based upon your climate and not someone else's calendar, which is one of the big things. I'm giving you a teaser handle we'll start with when we get going in this episode in just a second. But I want to officially welcome you to the podcast.
I'm your host, Melissa K. Norris, a fifth generation homesteader who got back to my roots of using simple, modern homesteading for a healthier and more self-sufficient life after a cancer scare in my late 20s. This is the place for you, my friend, if you've sometimes wondered if you weren't born 100 years too late, if you've always thought that you and Laura Ingalls would be best friends, and if you think that every home and kitchen would be better if they were filled with Mason jars and cast iron, and those things were used daily with homegrown and homemade food. If that is you, then welcome home and welcome to this amazing community of modern pioneers.
Okay, so how to start seeds indoors. The first things that we need to cover is, one, the types of seeds that are best started indoors because honestly not all seeds should be started indoors. This is something that I see happening a lot where people think that they should just start everything indoors so that they actually have this life plant that they can transplant outside. And that unfortunately is not the case. Some of your plants, you're much better off direct sowing, which is when you take the seed and you directly sow it into the ground outside either in a raised bed, in the container, or in ground in its final spot, so its outdoor growing conditions and its outdoor spot. You're just taking the seed and you're putting it directly there.
Most of your root vegetables are better off being sown outdoors. So carrots, beets, any of your outdoor items like that, you're better off just radishes. Radishes are very fast growing as well. There's no need to start them indoors. You can also start radishes outside when the soil temperature is pretty cool and they will germinate and grow really rapidly. There's no reason to start them indoors. Other plants will get really large and also don't like their roots being messed with. When you're seed starting them in containers indoors and then having to transplant them to larger containers or transplant them from their container inside to their final spot outside and it messes with their roots if their roots are really sensitive, you can actually damage the roots and the plant gets stunted and doesn't perform very well.
And that tends to be things that don't like their roots to be messed with at all are items in the bean family as well as your corn. Don't worry. I know that when you're listening, sometimes some of the info you're like, "Oh my gosh, I'm never going to be able to remember this, especially when we're talking about specific vegetable types." I have a chart created for you that is in the blog post that accompanies this episode. You can go to melissaknorris.com/291, melissaknorris.com/291, the number, 291, because it's episode 291. You will see a chart there of vegetables that are best direct sown and then those that do well with seed starting.
One is picking the correct type of vegetable to seed start indoors. And the reason that the vegetables that we're going to be seed starting indoors, why we would even start some of our seeds indoors is, one, is if you live in a Northern climate or a climate where you have a shorter growing season. This actually could be for a Southern or a Northern climate. But let me explain. If you live in a Northern climate and you're trying to grow warm or hot weather vegetables and you have a shorter growing season like I do, I don't have enough time between when the soil temperatures are warm enough for me to be able to direct sow a tomato and a pepper, which both are very susceptible to cool weather and need warm temperatures in order to germinate and to flourish.
My growing season is too short for them. If I were to try to just direct sow those seeds, if I was lucky, they would be coming to harvest time when my first frost would hit. But in most cases, they wouldn't even be at full harvest point. I wouldn't even get a harvest off of them before a frost would hit and just wipe them out. Essentially, I would get no harvest from them. Now, how this seed starting indoors can work in a Southern climate is a lot of times the summer climate has the opposite problem as I do with cool weather vegetables. If you're really hot and really Southern, you might struggle to have a cool enough timeframe to grow things like broccoli and cauliflower and cabbage that unfortunately when they're in those really hot temperatures and warm temperatures, they will either bolt or they just won't form a head. It's just too hot for them and they don't perform well.
Well, if you can seed start those in a controlled, cool environment in my Southern climates, then you have a longer cool growing season. You would seed start them while it was still hot out but as you were coming up to your cooler temperatures. Seed starting can actually work for both climates, but usually Northern climates will use seed starting for warm weather plants, some cool weather, and we'll talk about that too, whereas your Southern climates are going to be doing it more with cool weather plants to grow during their cooler time of year.
But seed starting indoors not only does it allow you to grow vegetables that you may not be able to grow with just direct sowing based upon your climate conditions, but it also is much cheaper than purchasing all of those starts from nurseries or a gardening store. It gives you much greater variety of what types of starts you'll be planting. So, for example, I could purchase tomato plants locally. Well, I should say in non-pandemic years. But even during the pandemic year, we were able to get... There was gardening stores and sections that were open where I live in Washington State. We were still able to get them.
But for tomorrow, I'm very specific about the type of tomatoes that I grow. And if you've been a listener of mine or are in any of my gardening courses, then you know I grow a paste San Marzano Lungo number 2, heirloom paste tomato, it's an Italian heirloom paste tomato to make all of my sauces and tomato sauces. It has a great flavor, but it's also a meaty tomato. It doesn't have a lot of water content. It makes thicker sauces and thicker sauces. For me, I'm not having to simmer them as long and they're not watery.
However, if I go to my local gardening centers, I have only once in the past, oh gosh, probably 10 years. One time have I ever seen a San Marzano Lungo tomato start available to purchase where I live, one time. That's why if you're seed starting them yourself, not only will you save money, but you also get to have control and grow the exact varieties that you want and you have a much greater variety available to you when you're seed starting them at home.
Now, after we have identified why we're seed starting them at home and which plants will do well when seed starting, the other thing is knowing when to seed start indoors. This is really key because if you seed start them too soon, then the plants are going to be really large before you're going to be able to get them outdoor in their proper growing temperature and environment. And so you're going to have to have more larger containers, more soil, more care, more area. Plants always do better when they're actually outside in direct sunlight. The timing is key so that you're starting them... It's like Goldilocks and the Three Bears.
If you start them too soon, they're going to be too big and they're actually not going to be able to grow as robust as they would be if they were outside in great growing conditions with actual direct sunlight. And then if you start them too late, then unfortunately they won't be of big enough size when it's time to plant them outside. There'll be too small to actually reach full maturity before your frost date comes and kills them if they are a warm weather plant that is susceptible to frost. So when to start your seeds indoors, all revolves around your first and last average frost date.
For seed starting your plants in this wintertime or to plant in a summer or spring garden, so usually you'll be starting them end of winter, early spring. You need to know what your last average frost date is in the spring. After you have identified that, then you look at the specific variety of plants that you are going to be seed starting and you count backwards. If you have my book, The Family Garden Plan or My Family Garden Planner, you already have all of these charts available for you in there. I've got it all laid out for you, so you can go there by alphabetical and know exactly when you're going to be starting the seeds for both summer and a fall vegetable garden if you're going to be doing a different gardening.
You've already got those, but if you don't have a copy of either of those, which I highly recommend that you go and get yourself a copy, if you don't, then I will have, as a freebie, a seed starting chart in this episode. Again, melissaknorris.com/291, go there, you'll see in the resource section there will be a link you can click on to get a seed starting chart for free that will have that information for you because it's very key that you get those weeks right before your first average or last average frost date, excuse me, in the springtime.
So, example, tomatoes are usually 8 to 10, sometimes 12 weeks before your last average frost date in the spring. So you'll look at that last average frost date and you're going to count backwards and that's when you're going to be starting those indoors. Pepper plants are usually eight weeks. Onions tend to be the longest. And those can be up to 16 weeks when you're starting onions from seed, which is one of the only root vegetables. In fact, it's the only root vegetable, not one of the only. It's the only root vegetable that I start from seed is an onion. Everything else I direct sow out into the garden and I don't root-wise fruit vegetable-wise and I don't start them from seed. Those are usually the three that have the longest runway time, or you're going to be starting them the earliest from your last average frost date are those ones.
So, how to start your seeds indoors, when to start your seeds indoors. We've identified the varieties and now we've got our weeks, when we need to plant them, what are we planting them into? This is another area when you're starting your seeds that a lot of people have issues with. And if you don't get this right, it causes a lot of problems down the road. And that is picking the right soil medium for seed starting seeds indoors. When you're starting your seeds indoors, you don't want to use soil just from your garden. I know this sounds funny, but you want to use sterile soil when seed starting indoors.
If you are purchasing soil from a store, a garden center online, whatever, and I'll have some links to some of my favorites in the show notes, at that blog post, you can go and check out, but it needs to be sterile, meaning that there's no disease. If you just go out to your garden and dig up some dirt and put it in and bring it in, there's a couple of issues. The biggest is it's not sterile. That means that there can be a lot of disease that's in that soil, as well as insect eggs. Trust me on this, you bring it into your house into a warm environment, which we're going to talk about temperature in just a moment for seed starting your seed indoors, and then the insect eggs will hatch out, and you've got all kinds of little bugs and gnats and all these little things flying around your house. Not fun.
But the real reason is because of disease and bacteria and fungus, spores that are on that soil, and when you bring them indoors and we're creating a very perfect environment of moisture and temperature, you have baby seedlings that are much more susceptible to disease and getting sick than you would mature plants. And because they're in this indoor environment where we don't have as much air flow, they're much more susceptible to those diseases. And that's why people will say, "I started my seeds. They were growing great. And then all of a sudden, they just all wilted and died." That is called dampening off disease. It is from a fungus and it's because you didn't use sterile soil.
I'm going to try and say that one three times fast, sterile soil, sterile soil, sterile soil. I did it. You didn't use sterile soil. You can purchase a potting mix. And now, you'll see a lot of things where it says to use a specific seed starting mix. You want to make sure when you've got these young little baby seedlings that the soil is well draining, but that it's light enough and has enough organic matter in it, that it's light and fluffy enough that the little tiny roots, because when it's first spread and we've got little itty-bitty, tiny little roots can get through the soil and it's not too hard and they're struggling and they can't get their roots down and established a good root system. That's another reason that we like to use a potting soil or medium as well.
Now, I don't purchase a specific seed starting potting mix, which they do have for sale and some people swear by. I just get an all-around potting medium soil. For indoor, I make sure it says for indoor potting and I have just been fine. I have not had any issues. That's the route and those are your options. Now, if you're like, "I'm not going to be able to purchase potting soil and I want to use my own dirt from home," you can bake your dirt at 200 degrees Fahrenheit until it reaches an internal temperature of 180 degrees Fahrenheit. But I don't want to deal with trays of dirt in my oven. It's a mess. And honestly, I would just rather buy the small few bags I need of my organic all-purpose potting soil and call it good.
You can make your own, and this is when you still need to sterilize it. But you would be doing equal parts of compost and top soil and sand, or people will mix in things like perlite, coconut fiber, different things like that so that it is light and loamy and it's not too compacted. I just find it easier, as I said, to just purchase a couple bags of potting soil myself each year to start my seeds with indoors. Now, seed starting containers. You can, of course, purchase seed starting containers. But for most of my seed starting, I use things that I already have around the house to start my seeds, or I will have purchased some specific sizes of seed starting containers. I use them every year, have used them year after year after year.
The key though... And I have a blog post, which will be in this post resources section, you can go and look at that in more depth, which goes through a ton of different seed starting container options. But you do need to make sure that you sterilize if you're reusing those pots, that they get sterilized each year before you start putting your new soil and begin starting your new set of seeds indoors. Very, very important for the exact same reasons that we need to use sterile potting soil so that we're not passing on any type of diseases.
Okay. The next thing, and this is one advantage that we have when we're seed starting indoors, is our soil temperature. Soil temperature is why we go by first and last average frost date and planting so many weeks outside after a frost or before a frost, all of those different things is because it's a general guideline for soil temperature. Most seeds, now this again is going to depend on warm weather plants versus cold weather plants, but most of your warm weather plants need a temperature between 75 to 85 degrees Fahrenheit for ideal germination rate, which means if you were to plant 10 seeds, all 10 would germinate. That's 100% germination and that's ideal germination conditions in order to get 100% germination rate.
So, 75 to 85 degrees Fahrenheit for your soil temperatures is going to get you quick germination and a high germination rate on those warm weather plants. Cool weather plants can germinate in much cooler soil temperatures and some of them can be down into the 50s and even the 40s depending on a few of those really hardy seeds soil temperatures. Important thing to remember is your soil temperature is not the same temperature as your air, especially outside.
In your outdoor growing conditions, you can have some days where it's 65 degrees Fahrenheit out, but that doesn't mean your soil temperature. Usually, your soil temperature is about 10 degrees cooler. Not always. And then it takes a while for that soil to warm up. That's usually why it's two to three weeks after your last average frost date before we can safely plant any type of warm weather plants, be it direct sow or transplanting the seedlings, the seeds that we're starting indoors outside.
When we are seed starting them indoors, the temperature of our soil is important, but it's also much easier to control a small amount of soil, which is why when we're seed starting, it's usually in very shallow and small containers. And then after those plants germinate and begin to grow and you get your first true leaves, you transplant them to a larger container because we can control a small amount of soil, temperature-wise much easier and we can get it to heat and have it to stay to heat than we can a large container of soil. We can also keep the moisture level there, which those are the key things for seed starting any type of seed and getting it to grow is temperature and moisture. And those we control very easily when we're seed starting indoors.
My home is usually between 65 degrees Fahrenheit and 75 degrees Fahrenheit during the winter months. It's warmer in the evening when the fire has been going all day and then it cools down in the morning when the fire has been... we've shut all the drafts down and as it's just barely going while we're sleeping at night and sometimes it will go all the way out, we'll rebuild it in the morning. I share that with you because I will put my seed starts or seed starting containers with the soil and the moisture right next to our woodstove. That's the warmest part of my house.
Some other options for finding warm conditions for your seats to start them can be the top of the refrigerator because obviously heat rises. That's why a lot of times people will put their bread dough on top of their fridge. It's a warm spot, or next to a heater, next to a woodstove. Never, of course, put it directly on a heater over a vent, but you can put it next to it and help to create that warmer growing condition. I have had excellent germination rate of all of my different starts by doing that, and I have not purchased seed heating mats.
Now, that I will say, I don't have good luck getting really hot peppers. I'm fine with sweet peppers and bell peppers, but really hot peppers like a cayenne or even jalapeno, I do struggle to get those to germinate because I can't get my soil quite warm enough. If you plan on doing a lot of peppers or your home is really cold, getting those seed starting mats can work very well. You plug them in and then you put your trays or your dirt on your whatever containers you have them in on top of that and it heats the soil and keeps it at a warm temperature for germination. Some people swear by them. And if you're going to be doing those hotter peppers like I said, or you have a cooler home, that's something that you may want to consider though I have personally never used one.
Now, we need to talk about the condition of the soil now that we understand heat and ways that we can keep our soil warm. We have to keep our soil moist. That's what seeds need. It's heat and warmth. It's actually not light when they're first germinating. They don't even need light in most cases when they're first germinating. They need the warmth and they need the moisture. When you're planting your seeds, if they're larger seeds that you're seed starting indoors, most of your soil depth will be on the back of a seed packet. It will tell you how deep to sow it.
But a general rule of thumb is however big the seed is, is to plant it that deep. For large seeds like pumpkin seeds, I'll put those down like an inch and a half down into the soil, though I don't start my pumpkins indoors. But for your really small seeds, like tomato seeds are very small, lettuce seeds are really small, your pepper seeds really aren't that large either, they're pretty small, I put those on the very top of my soil. I'll fill my containers with my potting soil and then I will sprinkle them on the top of the soil and then I will water them and the water will push them down into the top of the soil. I don't want them to go too far down, but it'll push them down into the top of the soil. And then if I can see any of them still, then I'll just do a small little sprinkle of soil right over top of them. But I usually don't even do that.
After it has been watered, then we need to trap the moisture in there and create a mini greenhouse. Depending on if you've purchased seed starting trays that have the lids, you just pop those right on. If you go in to see the post of the different container options, I will reuse like clamshell containers that you get for fruits that are made out of plastic, or even lettuce from the grocery store if you're buying them. But they have that hinge lid so I can clamp that down, that traps the moisture in there, or you can use plastic wrap, cover the top of the container over the sides obviously so that you're trapping in there, and then you can poke a few little holes in it with the clamshells. I just don't clamp it down quite all the way so that there is a little bit of air movement and air getting in there, but we really want to create that warm moist environment.
And then we are simply waiting for the seeds to germinate. Now, depending on the seed, most seeds averagely take between 7 to 14 days to germinate. The closer you get to their ideal temperature, then the faster they will germinate for you. But that's about it. And they don't really need any light at this time. Like I said, I don't have any grow lights on mine. They're not put into a window. Actually, windows can fluctuate a lot in temperature. So I don't recommend putting yours in windows at this point before they've sprouted. Near your warm environment is going to be best.
Now, some people ask, "Well, what about how to start seeds in a paper towel? I've seen people do seed starting with a paper towel. What is that?" That is what we call a germination test in most instances. And that's where you take a damp paper towel and you'll take, like I said, 5 or 10 seeds, and this is more along the lines if you've had seeds that you've been storing for a while and you can test to see how viable they still are. Because usually every year you go with a packet of seeds and the older it is, then the germination rate will start to decline on it slightly.
You could put five seeds for example and a damp paper towel or on a damp paper towel and then seal it up in a plastic bag, like a Ziploc sandwich bag. And then you'll let it sit in a warm area for 7 to 10 days and you'll see if it begins to sprout. And so when the majority of them have begun to sprout where it's been seven days, you'll see how many has sprouted. If all of them have sprouted, then you know they're really viable and that's like 100% germination rate on your test and you go ahead and sow them all.
If only a couple has sprouted, then you know you're going to have a pretty low germination rate. What that tells you is you're going to want to sow more of the seeds that you're starting because you know not all of them are going to sprout and we don't have a way of knowing which ones are going to sprout. I wish we did, but we don't, until we've grown them and we just see, "Oh, this is how many I planted, and this is how many actually sprouted and grew."
Choosing the right container to seed start within the beginning is key for knowing how many plants you need to be growing. A small container allows you to control the moisture and the heat content, but you also need to make sure that you have enough space in that in order to put all of the seeds and all of the plants that you want to be growing. Now, a lot of people say, "I plant or I sow double the amount of seeds for the actual volume that I want, just betting on that maybe only half of them will sprout."
And in my experience, I would rather sow more than too little because I can always thin them out and just keep the best ones. But then I'm guaranteed to have enough of everything that I want without having to go through multiple sowings and then getting to where I'm getting into too short of a growing season because I didn't get enough and then I'm like, "Oh, man, I don't know. It's been 10 days. And now, I see only three sprouted, for example, and then I'm planting again. And so then now I'm 20 days past when I really should have been starting them."
Most people prefer to plant about double or triple the amount of seeds and then fit them if too many of them sprout and you've got too many and just keep the best, most robust, healthy-looking plants. After your seeds you've got them moist, you've got them covered in that warm spot, you just need to keep an eye on the moisture level. It shouldn't be sopping wet, but you don't ever want the top of the soil to dry out because your seeds are at the top of the soil when they're first sprouting. You want to check it daily and make sure that it hasn't dried out.
I like to just use a spray bottle at this point and I will just miss the top of the soil if it starts to dry out. You can do bottom watering, where the bottom of the container, if it has holes in it, you can set it in some water and it will soak it up. But I just find it easier to just take a spray bottle and spray the top of the soil when the seeds are just sitting in there to keep everything moist and then it's not too much moisture.
Now, after your seeds have started to sprout, then we definitely need airflow, we need light, and we need to take the top off of our containers. If you live in a very Southern climate, you may be able to get away without having a grow light and using a Southern exposure sunny windowsill. But in my experience and having thousands of people go through my gardening courses and my seed starting courses and even with a book and that type of a thing, most people need to use a grow light. If you have ever had tall, spindly plants that have really thin, weak stems, or that fall over, or that are reaching for the light, then they're not getting enough light.
When using a grow light or an artificial amount of light, that light needs to be within two to three inches at the top of the plant. Most people, even if they have a grow light, I shouldn't say most people, a lot of people don't have the light close enough to the plant. They'll have it like two or three feet above the top of the plants and then the plants will still be reaching and still have little weak, spindly stems on them. You need to have it snugged right down, not touching, but just a couple of inches above the top of your plant.
And when using artificial light, you want to make sure that the light bulb is a full spectrum so that we're getting all of the light spectrum and wavelengths coming through it so that it is mimicking like they would get from the sun, but it's still not as good and as strong as the sun. And so you're going to be using that grow light usually 16 hours a day. I turn mine on first thing when I get up in the morning and it's the last thing that goes off right before I go to bed at night.
A lot of times people don't leave a grow light on long enough because they say, "Oh, well, most vegetables..." And this is true. "Most vegetables only need six plus hours of direct sunlight to be fine, but that's direct sunlight in the middle of summer, which is very different than just obviously a grow light, which is not the sun and in the winter months." I prefer to use a grow light and most people who have issues with the strength of their plants, it's because they're not using a grow light, or it's not on them long enough, or it's not close enough to them.
Warmth and temperature, once the seeds have sprouted, then we still want to keep the plants about 60 to 75 degrees Fahrenheit and go up to 80 degrees Fahrenheit. But the normal temperature of your house should just be fine. What you really wanted to make sure is overnight lows, especially things like tomatoes and peppers, they don't like to get in the low 50s. And if you are using a window and not a grow light, you need to make sure at night you are pulling those seedlings out of the window and away from the glass if you have cool nights because the temperature will drop a lot right next to the glass, a lot more than most people will think about. That's going to be your coldest spot. And so you don't really want to leave in there, especially if you're having freezing temps overnight.
Now, for watering, this is where people often get into trouble. When we are watering our plants, we don't want the soil to be soaking wet, but you don't want it to get too dry either. It's that whole like Goldilocks phenomenon. I use that analogy a lot, but it's really true. I will put my finger in there. After the seeds have germinated... Let me back up here. After the seeds have germinated and they'll pop up and you'll see the first little leaves that come off when a seed germinates and begins to grow as a plant, those aren't its true leaves. Those leaves begin to feed the plant, but you don't actually... That's why almost all seedlings when they first sprout look alike. It's hard to tell the difference, which is why labeling is very key, by the way. You want to label your plants so that you know what they are, especially within varieties.
But it's the second set of leaves that a plant develops that is actually what we call it true leaves. And they will actually look like the sawtooth edge of a tomato plant will be come out of the second set of the leaves, the curvy friendliness of like a curly kale you'll actually see from the second set, but is what we call its true set of leaves. Once a sprout has those first set of true leaves, it's critical that you get it under a grow light, it's getting the appropriate amount of light per day. And then you can let the very top part of the soil dry out, but you want to make sure that there's always moisture at the bottom.
You don't want the top to stay soaking wet all of the time at this point because then you'll get fungal growth. And none of us want that, or you'll actually see like a white mold surface begin to grow and develop on the surface of your soil and that's too much water. And so if you let just the top dry out just a little bit in-between waterings, that will take care of that problem. The older a plant gets too, it's good to let just that top surface begin to dry out because then the roots are forced to go down deeper into the soil and into the container, into the dirt, and it creates a better, more robust, deeper root system, which is actually a good thing provided that the containers you have them in are deep enough for the roots to go down.
Choosing the right container is going to depend on the plant because obviously something that's small like a basil plant doesn't have as large of a root system and doesn't need as large of a plant as something like a tomato plant. It also depends on how old it is. If your tomato plant is only a couple of weeks old, it doesn't need to be in a half gallon container of soil yet. But as it begins to reach closer to six weeks of age, you don't want them to become root bound. You want to check the bottom of your plants if they're going to be in there and developing up to a large size, that they don't become root bound and then potting them into a larger container with more soil if it looks like they will become root bound, or you start to see the roots circling around, or the roots coming out of the little holes at the bottom of the container you have them, and that's a sign, "Oh, we need to get this in a bigger container."
One of the other things is after we've got them all sprouted, we've got them growing under their grow lights, we're monitoring their water is our when to plant and timing, which all revolves around those frost dates. But what about feeding and moving your seedlings out doors? A plant has all the nutrition it needs until it begins to develop its first set of true leaves. When it's just those first little leaves that sprouted, it still has enough food within the seed from when it was sprouting and those that it doesn't need any additional nutrients.
But once you begin to get those first true leaves, it does need nutrients. If you have purchased a potting soil, like I said, an all-around potting soil, then it will have some nutrients in there and you don't really need to do any type of fertilization until the plant's about four weeks old. Now, some of your plants at four weeks old, you will begin hardening off and getting ready to transplant outside. But for your longer ones like peppers, tomatoes, and onions, that won't be the case and you will need to be doing some type of feeding. I like to use a liquid fish fertilizer concentrate and so then I mix the concentrate in with water and feed them that way. I will usually start doing that with my tomatoes and peppers at about four weeks of age and then just like once a week or even every other week to make sure that they have enough nutrition because they're in a smaller thing of soil.
Now, moving your seedlings outdoors because our goal is to get them established and large enough and then to get them outdoors within that timeframe of how many weeks beforehand, you need to do a process called hardening off. If you don't, this is when people plant their beautiful starts outdoors and then they die because they basically go into shock. Regardless of what the conditions are outside, no matter how warm and nice it may be, you need to do hardening off. And that means you take the plants outdoors for a couple of hours the first day and then you bring them right back inside.
We are slowly increasing the amount of time that they're spending outdoors and getting used to the movement of air, the wind, possible rain, this actual sun, because as we know, the sunlight is much stronger than what they're used to experiencing underneath their grow light. And so every day, I increase the time that my plants are outside by a couple of hours. So then over a seven-day period, by the end of that seven-day period, then they are able to stay outside for 24 hours and then I can transplant them and move them into their final planting spot.
Some of the troubleshooting questions that people have is, "Only some of my seeds germinated, what went wrong?" And that is simply very rarely do all of your seeds germinate. Now, if you didn't have soil temperature, it wasn't warm enough, especially for those really warm weather seeds, or like I said, those hot peppers, it may have been too colder soil. Also, if you let it dry out on the top, you didn't keep an eye on the watering and this seeds got wet but then they dried out, that can stop germination. But as long as some of your seeds germinated and you're like, "I had them at the right temperature, I didn't ever let them dry out, et cetera," then it was probably just the viability of the seeds. And as I said, if they were older, then each year, less and less of them will begin to germinate. It was probably that.
And it's really normal. Usually, almost all of my tomato seeds will sprout. I'll have a little bit less of my pepper seeds. But usually, you'll have at least a few plants that don't sprout when you're doing all of it. You can still do the germination test. I rarely do a germination test. I just go ahead and plant. But it doesn't necessarily mean that you did something wrong. If your seedlings are spindly, that is coming back to not getting enough light, either for long enough, or it's not strong enough and you need a grow light or your grow lights not close enough to them.
Another thing is sometimes ceilings, when we're starting them indoors, the stems, even if you're doing the grow light is we need to mimic nature a little bit because when we're outside in nature, you have that air flow and you've got wind and it's shaking the stem of the plant, which then makes the roots dig down deeper in order to stabilize it and it makes it stronger. You can put a fan on really low like beside the plants, not directly growing on it to create a little bit more airflow, or I'll just take my hand whenever I walk by turning on the lights during while I'm checking them for water and run the palm of my hand over the top of the plants, and that will do the same thing and stimulate those roots and a stronger stem.
Now, if the leaves on some of your plants are turning purple, and this usually happens when a plant is in a container longer than for just a few weeks, but if it's turning purple, that happens and happens a lot with tomato plants, but it's because you don't have enough phosphorus in the soil for the plant to get. That's a sign that you need to fertilize, or you need to get it in a bigger container with more soil so that it has more nutrients. What if the leaves on my plants are yellow? Why are my plant leaves turning yellow? Twofold, two reasons. One, can be not enough nitrogen. Again, this is a fertilization issue and can also be that they're in a small container with a small amount of soil and it's time to get them planted outside, begin hardening off if weather conditions permit, your timing is right, or into a larger container with more soil, or use a liquid fertilizer.
But if leaves on your plants are yellow, it's either a nitrogen issue, or it can be over-watering. If you are watering too much, you can actually cause your leaves to be yellow. One of the easiest things is to just back off on the amount that you're watering, make sure you're letting that top layer of soil dry out a little bit in-between each time of watering. If they're still yellow after that, or you're like, "I'm sure it's not over-watering," then it's usually a nitrogen issue. This is one of those things where soil testing in a large vegetable garden is great. I wouldn't bother doing soil testing, just a small winter seed starting, but too little nitrogen can cause yellowing. If you have too much nitrogen, which is usually not the case, unless you didn't follow the concentration rules on how to dilute it if you're using a fertilizer, can cause yellowing leaves. It's usually those three issues. But with seed starts, it's usually over-watering or not enough nitrogen.
Now, if your seedlings are looking great and then they fell over, that's what I mentioned earlier with that soil-borne fungus that's called dampening off disease. You definitely want to make sure you're using sterile soil to begin with, and that you're letting just the very top right after they have sprouted, that you're letting the very top of that soil dry out in-between waterings. And like I said, I know that that was a lot of information. To get all of those different charts and then links to the grow light that I use, I have a grow light that I use just in the corner of my living room.
I don't have a garage, or a shop, or even a spare room, or a greenhouse in order to start my seeds. I start all of them just in the corner of my living room. I have been using the exact same grow light and the same light bulb that came with the grow light, going on seven years now. It was well-worth the investment. It wasn't super expensive to begin with. But it has saved me so much money because under that one grow light, I did buy a second grow light last year because we increased so much. But prior to that, I can fit under one grow light. I can do 20 tomato plants, usually 5 basil plants, and then usually about 6 to 8 pepper plants. I could get all of that underneath one grow light.
But last year, I decided to do a lot of medicinal herbs and some other perennials that had to be started from seed and indoors. And so I needed to get a second grow light in order to grow all of those. But you can grow quite a bit under one grow light. When I think of the packet of seeds, is usually anywhere from a couple of bucks to maybe 399, depending on what they are. You're spending that if not more on one start at least where I live. And so I know it has saved me a lot of money over the years, and it allows me to get my gardening therapy on, which, if you saw, I actually had a shirt made out of that.
Many of you asked me to have a shirt made out of it after reading the quote in my book that says, "Gardening is great for the body and soul." And so you can go and check out that shirt. I'll have a link in the show notes as well if you want to snag one of those for you. But it really is true. Gardening therapy... Ah, seed starting is a great way to get your gardening therapy on, to get all of the plants that you need to feed your family. It saves a lot of money. And it's also can be really fun, especially with all of the tips that I've given you here, now that you know everything that you need to know about how to start your seeds indoors and do it so that they will be healthy and provide you with a lot of food.
And for our verse of the week, I feel this one is very fitting. It is 2 Corinthians 9:6, "Remember this, whoever sows sparingly will also reap sparingly, and whoever sows generously will also reap generously." And even if you sow too many seeds, you can always give them away to friends and neighbors. That's what we did last year. We were able to give people who hadn't started any and needed some tomato plants. We were able to give those away. I believe not only with gardening is it better to sow generously so that we can also share generously, but I think in all things in life.
I think the more generous we can be with other people that not to do it with just the intent we'll find generous and they're going to be generous back with me. But I do firmly believe obviously in the word of God. That's why I just shared it with you in that verse. But in the truth of that that when we sow generously, it will come back to us as well. I think the world would be so much of a better place if everybody were able to follow that.
Thank you so much for joining me on this episode. I hope you go and take advantage of all of those charts and resources that I'm giving you for free for your seed starting. And if you enjoyed this episode, please do leave me a review. It's really fun to read your guys' reviews that you leave me and share it with someone else that whole sharing generously things that we could have more and more people successfully growing their own food. My friend, blessing in Mason jars for now, and I'll be right back here with you next week.
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