I have never seen my fellow gardeners as excited as they were after the article on winter sowing appeared in the Northern Gardener magazine over a year ago. MN Master Gardener Michelle Mero Riedel wrote about a method of starting perennial and annual seeds that do not involve indoor lights, special soil, or even seed trays. In fact, once the seeds are planted, nature pretty much does all the work for you.
Too good to be true? I thought so myself and let all my friends be the guinea pigs last winter. No one was more surprised than I that almost everyone that started seeds using the winter sowing method was successful.
Winter sowing is a great way for new gardeners on a budget to fill a whole garden with perennials for only the price of a few packs of seeds. My gardens are already chock-full of perennials so I am using winter sowing to start my hardy annuals and biennials. Hardy annuals are the annual and tender perennial self-seeders that pop up every year in your gardens and will take a light frost in the early spring or fall.
Why do I want to start hardy annuals that are going to appear on their own anyway? First, because re-seeders usually take a while to get going and I don’t like looking at big holes in my gardens. Second, while I am waiting for the self-seeders to show up the weeds and other neighboring plants try to take over their place in the garden. By winter sowing in containers outside, I can plant good-sized plants right into the garden in late May and they are already hardened off and ready to start going strong in the garden.
You can winter sow your perennial and hardy annuals seeds during January, February, and early March while the weather is still consistently cold. Start collecting clear or opaque milk jugs, lettuce containers, 2-liter pop bottles or other similar containers months ahead of planting. MG Nancy Braschler came up with a great way to store jugs until you need them. Just bungee cord them all together by the handles and hang them over the rafters in your basement or garage until you need them.
When the time comes to plant, clean the containers well and rinse with a 10 to 1 solution of water to bleach. Then rinse well with water. Make a line with a permanent marker from one side of the handle around the jug to the other side of the handle and then using a utility knife cut the jug apart using the line as a guide and leaving a hinge at the handle so you can fold up the top. Cut several one-half inch long drainage holes in the bottom and then fill the jug or other container with 3 to 4 inches of very moist potting soil. It is easier to evenly dampen the potting soil if you work the water into the soil with your fingers before you put it into the jug.
Different seeds have different planting requirements so carefully read your seed packet for instructions on depth and spacing before you sow your seeds. After sowing make a plant label for inside the container and also write the name of the plant with a permanent marker on the outside of the jug. Use transparent duct tape (3M Performance Plus is one brand) to tape the two halves of the jug back together. It is easier to work with the duct tape if you use two pieces of tape about a foot long starting from one and then the other side of the handle and taping towards the front.
That’s it! Just put your containers outside on the south, east or west side of your house where they are not under an overhang and will be exposed to the rain and snow.
When Spring Arrives! As the weather warms up make more and larger holes in the top of the containers so that your young seedlings do not become overheated. Check the containers often to make sure that they do not dry out and when there is no longer a danger of frost the covers or hinged top can be entirely removed. You can either transplant your seedlings into a larger container or just leave them in the same containers until they are large enough to plant directly into the garden.