Imagine being able to suppress weeds and add nitrogen into your soil simply by planting the right plants at the right time. Sound too good to be true? It's not my friend.
This post is all about companion planting and living mulches. Learn how living mulches can work alongside no-till gardening methods, how to choose plants that will add nitrogen to your soil just by growing them, how to use them for weed management, and how they can help make your garden healthier (and you happier, amen!)
I'm so excited to be interviewing Jessica Walliser, a horticulturist, co-founder of Savvy Gardening, and author of many books, including “Good Bug, Bad Bug” and her newest title, “Plant Partners – Science Based Companion Planting Strategies for the Vegetable Garden“.
In today's Pioneering Today Podcast (episode #299), we're discussing both crop rotation and companion planting strategies, how to use living mulches to enhance and improve your soil, and what it looks like using them in different areas of the garden.
For a more foundational look into companion planting, check out episode 233 of the podcast where I discuss crop rotation advantages in a home vegetable garden with an entire segment just on companion planting.
I also discuss a bit more on how to get rid of bugs naturally with companion planting in podcast episode 266. Both are definitely worth checking out if this topic is of interest to you!
How Do Living Mulches Work?
For so long people have thought that cover crops supply the nitrogen only once the plant has been tilled under. It was believed that as the plant breaks down, it then releases the nitrogen into the soil for the next gardening year.
While this is true, there is actually a lot of nitrogen transfer that takes place while the plant is in a living state. And that's why we love using living mulches throughout the gardening season. You don't have to wait for that Crimson Clover to die and turned into the soil. You'll get more nitrogen that way, but you'll still get about 70 pounds per acre by just letting it grow.
This happens through the mycorrhizal network. This is a network of fungi that form under the ground, embed themselves in the roots of your plants, and send themselves out into the soil, taking carbohydrates from your plants in exchange for providing them with nutrients.
So this network extends underground between plants and is involved in transferring nutrients from plant to plant.
Because the roots of the Crimson Clover are constantly dying while others are growing, they're continually shedding their nitrogen-fixing nodules, releasing that nitrogen into the soil all season long.
7 Goals of Plant Partnership
When considering plant partnerships there are seven goals. You may be looking for just one, or a couple of these benefits, but by utilizing companion planting you can achieve the following goals:
1. Weed Management
2. Soil Preparation and Conditioning
3. Pest Management
4. Biological Control
5. Disease Management
6. Attracting Pollinators
Best crops for living mulch
You may have heard that leguminous crops are always best for cover crops. This is true because leguminous crops are best for replenishing and restoring nitrogen in the soil. However there are many other cover crops that are beneficial, it really boils down to the reason you're using cover crops.
- Crimson Clover – an annual legume that is a great companion for cole crops like cabbage, kale, collards, Brussel sprouts, etc.
- Medium Red Clover
- Sub-terranean Clover
- White Clover – do be mindful with white clover as it's a perennial living mulch, it will not die off after one year and tends to come back stronger each subsequent year. Stick to planting white clover between rows or areas where you don't mind it taking over.
- Vetch – this living mulch actually has the ability to suppress soil-borne diseases.
Benefits of living mulch vs. woodchips
Woodchips will eventually break down overtime, which means you will continually have to buy mulch to practice this weed supression method.
But with living mulches, you can actually plant them once and enjoy their benefits for years, especially if you choose your crops wisely and pick varieties that will add nitrogen back into the soil.
Annual vs. Perennial Living Mulches
The best way to go about pairing your living mulches is to pair like with like. So if you're growing an annual crop, then you'll want to pair an annual living mulch with that crop.
If you're growing perennial crops, something like asparagus, raspberries, blueberries, etc., you'll want to pair it with a perennial living mulch.
This doesn't mean you can't ever change this, especially if it's for something like a walkway. But it's just a general rule of thumb.
Do keep in mind the height of the cover crop when pairing with your vegetables because you don't want your living mulch to grow taller than the vegetable plant you're growing.
If you're trellising some veggies, you can get away with some of the taller living mulches.
How to Plant Living Mulch
You may be wondering when to plant out your living mulches. Do you plant your crops, let them become established, then come back and plant the living mulch? Or do you plant the living mulch and your vegetable seeds at the same time?
The answer is slightly before or slightly after. Jessica recommends planting the vegetable crop (or starts) out just before and allowing them to get established, then coming back in and planting the living mulch so there's no competition between the crops.
Ideally you want the crops to both be growing and flourishing at the same time. So just a couple of weeks between plantings is ideal.
Top Recommendation for First Time Cover Crops
Oats is what Jessica always recommends for the first timers cover crop. The great thing about oats is that if you live in an area where you get freezing temperatures in the winter, the crop will always be winter-killed so you don't have to worry about it re-seeding in the spring and taking over your garden beds.
All you need to do is sow them in the late summer, early fall, then once spring rolls around you just leave the debris in the garden and plant right through them.
Oats aren't legumes, so they won't fix nitrogen problems, but they will return organic matter and nutrients back into the soil. This feeds those beneficial microbes in the soil which, in turn, results in healthier soil.
How Close Do You Plant Living Mulch to Your Crops?
How close to plant the cover crop is determined by what the purpose of the cover crop is for.
For Companion Planting & Nitrogen Transfer
For this to work properly the living mulch needs to be planted right next to the crop. The nitrogen transfer won't happen if the crops are six feet apart, they really need to be planted right up under the skirt of the crop for proper transferring of nitrogen.
If you're just trying to build up the soil and condition the soil between plantings, then you don't have to worry about where you're planting it because this planting is done once your crops are done for the year (usually planted in early to mid-fall, depending on your zone).
Ground Cover & Weed Suppression
When planting living mulches as a ground cover or for weed suppression (like in your garden walkways), how close you plant to the crops will depend on whether you're growing annuals or perennials.
Because annuals will die back each year, you can experiment by getting the living mulch as close to your crops as possible for some nitrogen transfer.
However, if you're planting perennials, you may want to start by planting conservatively, so the living mulch doesn't spread too rapidly into your garden beds and take over.
A good rule of thumb is that it's always easy to plant more, but much harder to remove crops once they've built up a solid root system.
You can also read below for tips on how to keep living mulch out of your garden beds.
How Allelopathy Suppresses Weeds
Allelopathy is “the chemical inhibition of one plant (or other organism) by another, due to the release into the environment of substances acting as germination or growth inhibitors.” (Oxford Languages Dictionary)
We can take advantage of these compounds in the vegetable garden by growing cover crops and plants with allelopathic compounds that will restrict the growth of weeds, in particular from seed.
They don't work as well with transplants or large seeds, but for the smaller seeds that many of our common weeds produce, this can be very helpful.
For example, winter rye is used as a cover crop that's grown, then tilled into the soil to help amend the soil. But the allelopathic compounds can help restrict weed seed germination the next year. However, you'll need to be careful about planting seeds in the garden the following year, like lettuce seeds, or you may not get a crop.
How Long Do You Wait Between Planting Allelopathic Crops and Vegetable Seeds?
This depends on what cover crop you planted and what you're planning to follow the crop with. As a general rule of thumb, you want to avoid planting anything that starts from a very tiny seed (radish seeds, lettuces, kales, carrots, etc.).
You should be fine to plant something like zucchini, squash or transplants that have already germinated and established their roots.
How Do You Keep Living Mulch Out of Your Beds?
Because some of the perennial living mulches will send out shooters and continue to grow and spread, the best way to keep this from happening is by mowing down the crop before they drop their seeds.
Make sure you allow the clippings to drop right back down on top of the living mulch (using something like a mulching mower) because this will give you a big boost of nitrogen.
If you're planting near something like a raspberry bed, I suggest adding in a metal edging, if possible. Choose one that sticks up above the ground by about 2 inches and goes below the ground by about 2 inches. That will keep the living mulch from growing into those beds.
What is a Mulching Mower?
Not all lawn mowers have the option of dropping the clippings back down on the ground, many lawn mowers will shoot the clippings off to the side out of a shoot.
A mulching mower will actually keep the clippings rotating around the blades until they're chopped up into tiny pieces before dropping down onto the ground. This allows them to break down faster and keeps them from clumping up.
Resources & Links:
- Jessica Walliser's Website
- Savvy Gardening
- Plant Partners – Science-Based Companion Planting Strategies for the Vegetable Garden
- Crop Rotation Advantages in a Home Vegetable Garden
For more organic gardening tips, check out the following posts:
- 10 Things Most Organic Gardeners Forget About
- What is Organic Gardening and How to Start an Organic Garden at Home
- 13 Basic Steps to Starting a Vegetable Garden
- How to Create a Gardening Plan for More Harvest and Less Stress
- 8 Common Mistakes Made by New Gardeners
- How to Get Rid of Bugs on Plants Naturally Tips that Actually Work
- 5 Tips for Organic Pest Control for Vegetable Gardens
- Cabbage Moth and Slug Control with Organic Gardening Methods
Melissa: Hey there, pioneers and welcome to episode number 299. Today's episode is one you are going to love. We're going to be diving into on a deeper level, or I should say continuing the conversation around companion planting strategies for a healthier garden. So we're going to be discussing using companion plantings, not only within a no-till type environment, how companion planting can work with no-till, but we're also going to be talking about picking companion plants, this is the part that got me all kinds of excited, that will actually help add nitrogen to your soil simply by growing these companion plants. That means less amending of your soil with composted or aged manure or things like blood meal, which are typically how we will get extra nitrogen into our soil. So not only can you use companion plants to do that for you, but they also offer a lot of other benefits besides just the nitrogen part, but that's the part that really started to get me excited.
Melissa: So I am really excited to introduce you to today's guest, who we're going to dive deeper into with the companion planting. So it's a little bit of crop rotation, which has a spot within companion planting or as part of companion planting, but we're going to be diving into it beyond what I have covered in some past episodes. So after you listened to this episode, of course, you probably are going to want to check out episode number 266, which is how to get rid of bugs on plants naturally, tips that work, and that has a section on companion planting, as well as episode number 233, which is crop rotation advantages in a home vegetable garden. And especially episode 233, which is that crop rotation one, that's really going to help give a foundation for some of what we're talking about today, but today's episode is jam packed and really, really good.
Melissa: So my guest today is Jessica Walliser, who is a horticulturist and co-founder of the popular website savvygardening.com. Jessica is the author of seven gardening books, including, "Good Bug, Bad Bug: Attracting Beneficial Bugs To Your Garden," and her newest title, which is the book that I have, "Plant Partners: Science-Based Companion Planting Strategies for the Vegetable Garden." So this was really a fun episode because Jessica and I got to talk about a lot of our research that I had done for the companion section of companion planting inside the family garden plan. So if you have that book, you're very familiar with that. So Jessica and I had fun because we got to talk about a lot of the research that we did in the science-based part of companion planting, and then the ways that she has applied it and areas that I am super excited to be an implementing within my own garden.
Melissa: So you want to listen to this twice or have a pen and paper handy to take some notes, or you can simply, because I know if I'm driving or doing something, I don't typically have paper and pen handy when I'm listening to podcasts, you can always go to MelissaKNorris.com/299 because this is episode 299, not 199, 299. So MelissaKNorris.com/299, those numbers there, and we will have the written blog posts that accompanies all of this for you to go back to. If you don't feel like taking notes, it's kind of like I already did the note for you. So without further ado, let's get straight to this interview.
Melissa: I am super excited for this episode. So Jessica, welcome to the Pioneering Today podcast.
Jessica: So much for inviting me. I'm really excited to chat with you.
Melissa: Yeah, it was amazing. I got your book and I've always been fascinated by companion planting, especially... We had practiced some companion planting just for years based upon, I hate to use the word folklore, but almost with a gardening like we have, "Oh, these plants do well together," and it's just been passed down from gardener to gardener. And then of course now with the beauty of online, you get a lot of these things passed around, but when you go to actually... Why does this really work? And is there science that backs it up or is there different relationships that truly make these better plants to put with one another? And how does this all work? Or is it just something that people have just done for centuries in some instances, but it's just some of those things we've always done because everybody says to always do it?
Melissa: So when I was doing the research for the companion parts in my book, I just found it fascinating diving into the studies and trying to find studies in some instances because there haven't always been studies done as I'm sure you ran into, too. So I was really excited when I started going through your book. I was sharing with Jessica before we started recording this, I was like, "Oh, I feel like she's writing what I wrote," the way that we approached it and we thought about it. So I was really excited though, because your book goes into aspects of companion planting that I didn't dive into in my research because I was studying or focusing more, I should say, on the repellent and attracted crops to repel specific pests and/or attract the good predatory pests for pest control in the garden. But you go into a lot of different avenues, and the one that I got super excited about, which we're going to be talking about today, is actually chapter three from your book, but it's using companion planting for weed management.
Melissa: I feel like I'm in church and need to say hallelujah for weed management. [crosstalk 00:05:44]. But using those living mulches and allelopathy, and I feel so good, you guys, she told me how to pronounce that correctly, but using your companion planting as living mulches and allelopathy, that actually helps combat weeds, but also can be a way of amending your soil and putting nitrogen back in simply by these plants that we're planting and not having to have another source like aged manure or blood meal, or some of those other ways that we can add nitrogen into our soil, but actually doing it with some living plants. So I'm really excited to dive into this. So, Jessica, take it away, my friend.
Jessica: Sure. Yeah. Basically, I started the book with these seven goals of plant partnerships. You already talked about the pest management one, the biological control one. There's a chapter on disease management, one on attracting pollinators. But the first two, I think, are really closely connected, and that's the weed management one that you brought up and also, the chapter on soil preparation and conditioning. A lot of ways that we do plant partnerships with those goals in mind is through using those living mulches. Living mulch also has that extra bonus of the weed management too. Whereas some other cover crops do not because we're turning them in and when we turn them in, we're bringing up weed seeds from in the soil bank, we're disturbing the soil. Whereas the living mulch just put on top of the soil and you're not tilling or turning up the soil. So it's really a great way for you to get long-term weed management in the garden. But here's the deal, and you know this because you've grown cover crops before is, it can go wrong, right?
Jessica: It can go really wrong. Cover crops, if you don't know how to manage them properly, if you don't choose the right species, if you don't mow them down at the right time, there's a chance for it to become just a weedy disaster in your garden. So when I was writing about these two chapters, I was digging up all this research about these two benefits or goals of companion planting, it became really clear to me that I not only had to tell you about those planned partnerships, but I also had to tell you how to do them so that you avoid having all of these problems.
Jessica: The other thing too is I'm a no dig gardener. So I don't till or turn my swale at all in my vegetable garden, and I haven't for many years and I didn't when we had our organic market farm either. So the goal was to just not disturb that soil food web at all. I didn't want to ever disturb. So that's an extra layer of pressure when you're using cover crops because you don't have that sort of backup of I can always turn it under and that will kill it or effectively knock it back. So that's when all the timing and the crop selection really come into play.
Melissa: Okay. I love this. I feel like I straddle both sides of the fence, which sounds funny, but we have one section of the garden that we did as no-till for a test because my husband and I both work in the garden. So it's both of our domains and he is more skeptical to change the way that we're doing things when we're getting a really good result. We've had really healthy soil, really good yields and with practicing using tilling. However, I kept pressuring. I'm like, "I really want to try this." So we made a deal. This was two years ago. I said, "I'm going to do half of the garden with wood chips and not tilling it, and we're going to run an experiment." So then that way, if we don't like it or if we feel like things aren't going well, it's only done to half the garden and we can reverse it. It'll take some time and work, but we can reverse it.
Melissa: So he was like, "Okay." We did the compromise, and so we did the whole experiment. It's now going on two years now and we're going to be transitioning the rest of the garden over actually to not doing tilling and be getting wood chips in that home, all of the layers and how we want them. So I sowed that area though. Like this when we were putting everything to rest and stuff, I did till in some of the old crops that we'd harvested and just did a late till into the soil until I could get all of the covers down that I wanted, so I'm like, I have to do full disclosure. I do practice a little bit of both. But I really was interested with the part of the living mulch, because I have to say with the wood chips, they do break down over time. So you are adding new layers. I added some compost too, as well to the garden and then add another layer of the mulch.
Melissa: The living, which is going to require some work too. But it's not bringing in and shoveling all of this stuff on there because you're broadcasting the season and that becomes the living mulch. Whereas you're not having to go out and perhaps purchase. Most people have to purchase wood chips if they can't get them from like ChipDrop or something like that. So I'm very intrigued by it for a lot of those reasons. So with the living mulch, obviously it's very similar with cover crops. For those of you, if you're not as familiar with the benefits, I suppose, of cover crops, it's to help with erosion and to keep compaction down at the bare soil. If it's bare, then obviously we're seeds can be dropped on it from the air and the wind or whatnot, and then sprout into more weeds.
Melissa: But with these living mulches, if you're picking the right crop, you actually can introduce nitrogen back into your soil and surprisingly, a lot more than I think people would expect the levels of nitrogen that can be put into the soil depending upon the crop that you pick. So can you walk us through some of those best crops to pick if you're looking to introduce more nitrogen into the soil with your living mulch? Then also, like you said, though, really understanding how this crop works to make sure it doesn't take over your garden.
Jessica: Exactly. We all know, most people probably listening know that the legumes, leguminous crops are best for nitrogen because they fix the nitrogen from the air and convert it into a form that's usable by other plants with a symbiotic relationship with soil bacteria. Crimson clover is one of my favorite annual legumes to use as a living mulch. There's some really great studies that looked at it in combination, in particular with cold crops. So if you are a lot of cabbage and kale and collars and Brussels sprouts and all that, that's an excellent combination. One of the things that I do talk about in the chapter on slow preparation and conditioning is the fact that for so long, people think that cover crops supply the nitrogen, but they don't supply it until you till it under and they break it down and then it's released the next year. But the truth is there's a lot of nitrogen transfer that actually takes place while the plant is in a living state.
Jessica: So that's what happens when you're using living mulches. You don't have to wait for that crimson clover to die and turn it into the soil to get the benefits of that. Yeah, you're going to get probably more nitrogen doing that, but you still get a good amount. I think it was 70 pounds per acre or something like that. [crosstalk 00:12:38] I don't have the number in front of me, but yeah, it was a great piece of research. But how that happens, and this is something that the science is really just emerging on, but one of the primary ways that happens is through the microrisal network. So the network of fungi that live under the ground and form the relationships and they embed themselves in the roots of your plants and they send out into the soil and they take some carbohydrates from the roots of your plants in exchange for bringing them nutrients. So the microrisal network underground extends between plants. It's involved in transferring nutrients from one plant to another and through the soil, through soil organisms as well.
Jessica: So that's a great way to have that nitrogen transfer in the living state. And of course, roots of plants are always dying. So the roots of that crimson clover are constantly shedding the nodules. The nitrogen fixing nodules are constantly shedding off of the roots. As earthworms chew through the soil or whatever, they get shed, they release their nitrogen into the soil for whatever plants are partnered with that crimson clover. So crimson clover, medium red clover, subterranean clover, white clover, I watch with white clover because it is really a permanent living mulch, so that would be a better one to do between the rows of plants versus a crimson clover or a subterranean clover, which you could do and would die in most climates, at least once it get freezing winter temperatures. So all those leguminous cover crops are really good. There's a couple studies too that looked at vetch, which is another legume and its ability to suppress certain soil borne diseases, which is another topic that I cover in plant partners, but you get all these extra added benefits of it too.
Melissa: Okay, I love that. And I actually have a question for you with the white clover because we have white clover that grows just natively here where I live, and like you said, it is a perennial. It'll kind of hibernate in winter.
Jessica : Yeah.
Melissa: But then it just starts growing again and spring comes. And if you're putting it in the pathways, and so obviously in a no-till situation, then what's your best management tool for keeping it out of the rows where you're putting in your crops, especially if you're doing some direct sowing of seeds? What's your best management tool for making sure it in just the pathways and then not the actual growing space, especially for direct sowing? Or do you worry about that?
Jessica: Yeah. I always worry about that, especially with white clover because it spreads by runners, it spreads by seed and it's a really great thing to have, but it's just one of the things where it's quite possible to have too much of it. So with all cover crops, your best management tool is a mower.
Jessica: And that is one of the things that people neglect when they're growing cover crops, either as a living mulch or as a cover crop, a soil conditioner is the regular mowings. What's cool about something like the white clover is you are mowing it a couple of times throughout the year, especially when you've got a lot of flowers on there, and obviously you want to do that in the morning or in the evening when there's no pollinators active on it, you you want to regularly mow before they drop seed. What happens is when you mow, use a mulching mower, let those clippings drop in place and then boom, you have a big old nitrogen once the soil microbes get ahold of that, the clippings, you've got a big nitrogen release into the soil. So that's a bonus. So keep it regularly mowed, especially when it's ready to set seed.
Jessica: Then the other thing you could do is let's say you're doing it between Rosa blueberry bushes or blackberry brambles or something like that, I would actually consider doing a metal edging to those beds if possible; one that sticks up above the ground by about two inches and below the ground by about two inches. That's going to keep it from creeping over into those areas. You can get metal garden edging like that from a wholesale landscape supply center and it's really not all that expensive. It's more the labor to install it, I think, than anything else.
Melissa: Okay. And that was exactly what I was going to ask you. You just nailed it without even having to go there, so I love that. Then you said a mulching mower. Is this different than a regular push lawn mower?
Jessica: I don't know that they make all push lawn mowers mulching, but basically what mulching is, it blocks the clippings from getting spewed out that side chute and instead, it keeps the clippings circulating through the blades multiple times. It chops them up into tinier pieces and that way, they decompose faster, they're distributed out on the row or out on your grass, and you don't get those big clumps of lawn or big clumps of grass or the clover. It just chops it and shoots it out in smaller pieces.
Melissa: Okay. That makes perfect sense. Once you said that, I'm like, yeah, you wouldn't want it shooting. You would want it to be dropping where you were cutting it. [crosstalk 00:17:22] Okay, great. Thank you for that distinction. So with planting the clovers, and we really talked about the white clover is a perennial, ways to make sure that keep that in the area that you want it and not spreading. Now, time of year to plant some of these different ones. Obviously, it will depend upon your climate somewhat as far as when these seeds will germinate at temperatures and whatnot, but with the non perennial, so in more of our annual, like the crimson clover that you mentioned, what's the best practice as far as growing that as far as getting your timing; either time of year to get it going and all sorts of the timing with your other regular crops?
Jessica: Yeah, and that depends. So much of that, there's not a blanket answer to that really. It depends on what you're partnering it with. So let's say you're partnering your crimson clover with your row of grapevines. That obviously you just want to... Only thing you would need to worry about there is that you're planting that crimson clover at the best time. I would say if there was a general rule that we're looking at, we're looking at, you want to partner annual vegetable crops with annual living mulches. You want to partner any kind of perennial food crop with a perennial living mulch. So that just makes sense in general, that the perennials go with the perennials and annuals go in with the annual.
Jessica: So it's not to say you could ever change that, especially if you're talking about using it in a walkway or something like that. But for the most part, that's something that you want to consider. Also, you want to consider the mature height of that living mulch as well. So if you're growing taller food crops like tomatoes or okra or a vining crop that will grow up a trellis or something like that, it's not having a tall cover crop as a living mulch is not a big deal, but if you're growing lettuce or radish or some other really tiny vegetable, then you want to make sure that they're not going to be out competed by whatever living mulch that you're choosing to partner it with.
Jessica: So it has to be a thoughtful process. You can't just go and buy seeds for a cover crop and just generally grow it in your garden as a single all encompassing living mulch because it doesn't work that way. It will be fine if you're using it only as a cover crop and you're just planning on demoing it down in the spring and that's that's okay, but as a living mulch, it's a much more thought full process.
Melissa: Okay. So specifically with the crimson clover and the cold crops because we love our cold crops here. One of the reasons, we like to eat them, but secondly, I live in the Pacific Northwest, and so we're a cooler climate. Even throughout the summer months, I can grow cold crops even throughout the summer for the most part. I just have to be careful with my timing so that my broccoli doesn't bolt. So cold crops are something that we grow a lot of, but they are very nitrogen hungry crops. They require a lot of nitrogen. So I'm really looking to use the crimson clover with the cold crops. I'm very excited about that. So as far as direct sowing, the crimson clover, and then also planting out my cold crops with the planting of those, is it best to direct sow them at the same time or to direct sow the crimson clover and then put my seedlings in if I'm seed starting them? The actual planting time, if I'm wanting to them to go in conjunction with my cold crops, what's best practice for that to happen?
Jessica: Yeah. I would either go slightly before or slightly after those crop transplants go out into the garden, and that's going to help you limit competition. You want to have them both be actively growing at the same time, but you don't want to risk competing at all. So slightly before or slightly after. I personally prefer to sow my living mulches after because obviously the crop itself is going to have priority. So I want to make sure I get that placed in the right spot, and then I can sow my cover crops around those plants wherever I decide to put them.
Melissa: Okay. And I get asked this a lot, so I'm really glad that I have you on here. With getting the companion plants in this case, the living watch that we're talking about, how close does it really have to be to the plant to have benefit? Because somebody were like, "Oh, it's got to be within a foot or as long as it's within three foot," or is there really a guideline like that? Can you get it where it's too close because of competition, some competition for nutrient and space? Is there best practices as far as that goes?
Jessica: Yeah, it really does depend on the purpose that you're planting that cover crop for. So if you're planting it for nitrogen transfer while it's in a living state, they have to be right up against each other for that to happen because a fungal network is huge obviously, but there's less of a chance that it's going to actually partner those two plants if they're six feet apart. Much greater chance, if that clover is under the skirts, so to speak, of the harvestable crop.
Jessica: If you are doing it for soil building and soil preparation and conditioning, they're not actually in the garden at the same time. In that case, you're going to do your cover crop over the winter or in the off season when the garden is fallow, and then your vegetable crop during the growing season. So if it's for soil preparation, there's that. If it's for living mulch, it depends on what the partners are. Again, if you're using a perennial one, you might want to just stick with it in the rows. If you're using it as an under sowing, they can be right up against each other and you can see the benefits for that. So it just depends on what you're looking for and what results you're looking for out of any specific combination.
Melissa: Okay. Then some plants, I found this as far as the weeding part goes, this was a part that I thought was really interesting and also when that you would want to be educated on before using, but that was there are some plants that they actually can use a compound or a chemical, so to speak, that will, after they have been planted and that they are in the soil, that they will inhibit certain seeds from sprouting. So it helps with weed control and that aspect, not just because the top of the soil is covered. So can you talk to us a little bit about that?
Jessica: Sure. It's called allelopathy and these chemicals or compounds that are produced by plants, there's many allelopathic compounds out there that are produced by plants, but they're basically plants interact with each other in many ways. One of the ways that they do is by inhibiting or restricting the growth of nearby plants. It's to reduce their own competition. In the wild, one of the plants that's been really well studied is introduced weed called garlic mustard, which has taken over the Eastern US here in our wild spaces. One of the reasons that weed has been so successful is because it produces a group of allelopathic compounds that restricts the growth of nearby plants. So the potential for it to really change the whole composition of the trees that are found here in our Eastern forest is huge because it limits the growth of these other competing species.
Jessica: So we can take advantage of that, of those compounds in the vegetable garden by growing cover crops and plans with allelopathic compounds that will restrict the growth of weeds in particular, from seed. That's where most of them have their inhibition. They don't work so much on transplants or really large seeds, but crops that have really tiny seeds are very successful with this. So one of the ones that we've known about for a long time, it's been very well studied in the agricultural arena is winter rye. Winter rye is grown as a cover crop. It's tilled and turn into the soil. Then the compounds in it, the allelopathic compounds can help restrict weed seed germination the following year. So if you're using that as a cover crop, you don't want to plant seeds the next spring of lettuce or radish in that same area because it can restrict those seeds as well. But if you are smart about it and you're aware of the choices you're making, you can also use these compounds to really help cut down on weeds.
Melissa: I was really intrigued by that. When I was reading that, I'm like, "Oh, it's like black walnut," which is why we don't want to use black Walnut bark is mulch for a lot of things because of the [inaudible 00:25:27]. I didn't realize that winter rye, as you were saying, had some of those aspects, which was fascinating because we have a neighbor, an elderly gentleman up the road from us whose garden has one of the most beautiful gardens ever, vegetable garden. Every winter, he would plant winter rye. Now, I'm like, "Oh," that is one of the reasons that his garden did so phenomenally well because everybody surrounding who had gardens, nobody was doing a cover crop. So it was like this light bulb went off. I'm like, "Oh, I actually got to see this in action over a 20 year period as well, growing up seeing his garden." So I geeked out about that and I thought it was really cool.
Jessica: It is really cool. Farmers have been doing it forever. There's a ton of research. I have a bibliography in the back of the book that lists a lot of these research studies. They're done on large scale. So they're done at research facilities, at university, working farms and things like that. This is the best science that's available to us as home gardeners. There's not a lot of research that takes place in a home garden environment. So we do have to do a bit. We have to be willing to be a little bit of flexible, do a little bit of experimentation ourselves so that we can take these concepts that were studied on a farm environment and extrapolate them down to how they might work in a home environment.
Jessica: For me, cover crops or something, a lot of gardeners home gardeners are hesitant to get into again, because either they've done them wrong in the past or it just seems like so much work. But in the case of your neighbor there, what a perfect example of someone who's doing it successfully and someone who you really could learn from and learn how to use those techniques in your own space?
Melissa: Yeah. No, he always tilled his under. So with using the winter... I have two questions for you. So for those who are practicing no-till with a winter rye, obviously you want to get winter rye and make sure you're not getting a perennial version of ryegrass, of introducing that. So like you said, the type and making sure that you've got the exact right variety for cover crops is really important for that aspect, but he would always tell his under in the spring before he would plant. But if you're doing no-till, with the winter ryegrass how, are you just doing the mowing so it's like a chop and drop scenario? Will it continue to grow into the summer if you don't till it? How is the best management done there?
Jessica: Yeah. So the cool thing about winter rye is if you do no-till, you don't till it in and you leave the residues, you mowed it at the right time and leave the residues in place, you actually get better weed control for months. There was an interesting study that determined it was between 43% and 100% reduction in certain group of really common weeds and their germination when leaving those residues in place with winter rye. So you always, with cover crops, timing is everything. If you are going to do no-till and cover crops in combination, you have to mow them down when the plant is done flowering, but before the seeds are fully mature. And that is with any cover crop. It's really important that you do that.
Jessica: If you wait too long, they're going to go to seed and you're going to have a problem. If you don't wait long enough, they're going to resprout and that's going to be a problem because they're just going to keep on growing. If you mow them down with a mulching mower, a lot of people will cut them down by hand and then run the mower over the top of the debris that's already been cut down by hand, or they'll use a string trimmer to cut it down and then mow that. Leave all that, the detritus in place and the residue in place And that's what's going to give you the long time thing. But here's the thing, so winter rye is not the one that I recommend for first time cover crop.
Melissa: Okay. Okay, good. Okay.
Jessica: Oats is always the first one. Now, oat does have some allelopathic chemicals. It's well-studied and well-researched. The cool thing about oats is if you live in an environment that gets freezing temperatures in the winter, it's always winter killed. So the chance of it coming back in the spring and going gangbusters and seeding everywhere and becoming really problematic is greatly reduced. So for first-time cover croppers, I'm like go for the oats because you can't go wrong with them really. You sow them in the late summer, early fall. Let them through the winter. We get a couple of real good cold days, depending on where you live through the winter. You just leave the debris in place and you plant right through it the following spring.
Melissa: Okay. Now, with the oats, do those also, besides just having our weed control aspect, do they also introduce any type? I know they're not, I don't think they are anyways, a legume, but do they introduce anything into the soil like nitrogen, like some of the clovers or not really?
Jessica: Yeah. So they are not leguminous, so they don't fix nitrogen. But of course, any plant matter actually contains nitrogen and many other plant nutrients. So you still have that ability of that cover crop to add nutrients, return nutrients to the soil after it's done growing. Then, and of course it's also returning organic matter to the soil, which for me, that's super important because it's feeding all those beneficial soil microbes whose job it is to feed your plants. So anytime you're adding organic matter like that to the garden, it's a good thing. Doing it through the use of cover crops, like oats, is a great way to do it.
Melissa: Okay. So my next question is we have done either... So we've done the oats for our first year to make sure we have a good handle and don't have any issues of things going invasive or growing more than we want them to and/or the winter rye, or any of these that have that alle- I'm going to say it wrong. Now, I had it earlier.
Melissa: Thank you. Thank you. Yes. That have that. So how long, if we are going to be doing, say direct sowing smaller seeds like carrot seeds, lettuce, a lot of our leafy greens, some of those smaller garden seeds, is it months? Is it weeks, or don't sow it where you need to be direct sowing only in areas where you're going to be transplanting or planting larger things like bean seed or summer winter squash, et cetera? How do we manage that?
Jessica: Yeah, that's a great question. So it depends on the amount that's in there. It depends on if you've been doing cover crops for many years. Obviously, the potential for the compounds to be there in greater amounts is higher. Some of them break down really quickly. Some of them last in the soil a little bit longer, so there's a lot of different factors. So I would say if you're a first time cover cropper, be safe. Don't put those allelopathic cover crops in an area where you're going to be sowing lots of tiny seeds the following spring. Maybe by the time you get around to doing a fall crop or something like that, it's not going to be as problematic. So you just have to be willing to do a little research in your own space to see. But you're pretty much always safe with zucchini seeds and larger beans and things like that. Then obviously, transplants are safe to do as well. But I would stay away from the teeny, tiny seeds the very next spring after growing one of these allelopathic cover crops.
Melissa: Okay. I'm assuming with the allelopathic, because if we're doing something that's an onion start or garlic where you're planting the clove though-
Jessica: Yeah, that's fine.
Melissa: Yeah, and those types of things. Okay, great. Great. Now, the other question that I have, and I think that we'll wrap it up because we've actually packed a lot in here. It's a lot to digest, but I'm really excited about it, is you have done your winter crop and we've chopped and dropped it at the right times, but we've left those roots in because we're not doing the no-till and we've planted our crops. So when the next fall comes around, which is typically when we think of sowing another cover crop or the end of summer, depending on when your first frost hits, et cetera, has it broken down enough that you're going to be able to broadcast a new seed and have it grow? Or can you experience a problem being able to sow a lot more of a cover crop because that ground has been covered already?
Jessica: I do think some that... That's a really good question, and I do think it depends somewhat on the health of your soil. If you have been adding organic matter and you have a very biologically active soil with a lot of soil organisms seen and unseen, there are a lot of microbes in their processing that organic matter, it's going to break down very quickly, especially the grasses, which are in general, thin stemmed and they are quick to decompose. If you cut them, when you cut them down and you cut them to tinier the pieces are, the faster they're going to break down and decompose. So that matters as well. If you're using a roller, because that's another option is to just roll the cover crops over, which basically breaks them at the ground level and lays them down, if you're just doing that and leaving them whole, it's going to take a lot longer for them to break down and decompose.
Jessica: So one thing I might suggest that people do, and this is what I do in my garden, is after I mow and I'm getting ready to plant, I'm going to put down some organic matter in the garden, whether that's compost or some leaf mold or some very old manure, horse manure from the neighbor. I'm going to put that down. I might put an inch or so down, fling it out over on the garden. And again, that's introducing more microbes. That's speeding the decomposition because you've got the microbes now on top of the soil and on top of the detritus from the cover crop. So all of those things can act to influence the rate of decomposition of that material that's left on the soil surface. So for me, it's never been problematic. I've always been able to... Oats is my favorite thing to use. I've used lots of other things, but it's my reliable in my garden. I've never had problems growing. It's always pretty much decomposed by the time the fall comes around and I'm ready to sow the next crop.
Melissa: Okay, perfect. I think we have a great starting point and introduction to begin using these techniques. I'm thrilled. I can't wait to go through the rest of your book and to glean even more tips along those lines and increase my own companion planting use beyond what I have been doing. So for those who are wanting to connect further with you and this information, of course, your book, which we will have in the blog post, show notes for this episode, Plant Partners, but where else would you direct people to get in contact with and learn more about this type of gardening?
Jessica: Sure. I would say probably the easiest place to stir my website, which I own with two other professional gardeners and horticulturists. It's called savvy gardening, S-A-V-V-Ygardening.com. We do have some articles that were more coming on science-based companion planting strategies for the vegetable garden. There's a great one on companion plants for tomatoes, another one companion plants for zucchinis. So we've got lots of information about all kinds of gardening up on Savvy Gardening. If they want to know more about me specifically in what I do, they can go to my website too, which is just JessicaWalliser.com.
Melissa: Awesome, Jessica. Thank you so much for coming on and sharing all of your wisdom. We appreciate that.
Jessica: Thank you very much. It was my pleasure. I'm so happy that I was invited.
Melissa: Well, I hope that you enjoyed this episode as much as I did because I had a lot of notes and have already ordered some of the clovers. We're going to be testing them out in the pasture and I'm going to be able to sneak some of that seed and get that in at the right time to try with our vegetable garden. If it's not this spring, then it will be coming into the fall and next year, but I've already got my seed on hand. I hope that you had a lot of great takeaways and I can't wait to be back here with you next week. Blessings and mason jars for now.
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