Rinse and pat dry rhubarb stalks. Chop into 1 inch pieces. Place into a large bowl and sprinkle 1 cup sugar onto chopped rhubarb. Stir until well combined. Cover the bowl with a tea towel and allow to sit for 4 hours.
The sugar will pull out the juices from the rhubarb stalks, creating a lovely rhubarb syrup.
Wash 4 pints in warm soapy water and rinse. Fill water bath canner with water and begin to heat. Fill a kettle with a few cups of water and bring to a boil.
Dump rhubarb and syrup into a large pot. Bring to a boil and boil for 30 seconds, stirring. Take off of heat and ladle 2 cups of rhubarb into each pint jar with a generous 1/2 inch head space. Pour syrup over rhubarb, dividing it evenly between the four jars to a 1/2 inch head space. Remove air bubbles by running a spatula or knife around the outside of the jar and add more syrup if needed. If you run short on syrup, add boiling water (hence the kettle boiling). Wipe rim of jar clean, put lids on, and screw down bands.
Place in rack and immerse in water bath canner. Bring canner to a boil, making sure at least 1 to 2 inches of water cover the top of the lids. Process pints for 20 minutes with lid on. After 20 minutes, remove lid, let sit for 5 minutes, and then transfer jars onto a towel folded in thirds. Let jars cool for at least 12 hours without moving and check seals.
Pressure Canning Instruction
Follow above recipe through step 3.
Place rack in pressure canner and ad specified amount of water. Place jars on rack. Allow pressure canner to vent for 10 minutes. Use 5 pounds of pressure and process both pint and quart sized jars for 8 minutes (if 1,000 feet above sea level use 10 pounds per pressure).