Most people probably think the only way to start seeds in January is to pot them and place them on racks under special lighting in the basement or dining room. However, there is an easier and cheaper method called winter sowing. The snow may be falling, the wind may be blowing and the temperature definitely dropping, but that is the perfect time to winter sow some seeds, put the containers outside and forget about them. (Well, almost.)
Ten years ago my husband and I built our home, and a big, empty yard cried out to be filled. While looking for seed starting methods online, I stumbled upon the website wintersown.org. This method sounded too good to be true: Use freely available recycled containers, grow plants for mere pennies and achieve healthy, hardy seedlings with no damping off. Trees, shrubs, perennials, annuals, vegetables and herb seeds planted in the warm indoors patiently wait outside for the right temperature and lighting to germinate.
The USDA describes winter sowing as, “A propagation method used throughout the winter where temperate climate seeds are sown into protective vented containers and placed outdoors to foster a naturally timed, high percentage germination of climate tolerant seedlings.”
After further reading about the method online at the GardenWeb Wintersown forum, I gathered the supplies and dug in (so to speak).
Constructing the Containers
Search the recycling bin for milk cartons (plastic and cardboard), plastic coffee cans, produce boxes for strawberries and spinach, large soda bottles, cat litter tubs, cottage cheese containers and drinking cups.
The preparation of the container depends on the type used. All containers need a height of at least 5 inches with drainage holes and ventilation slits in the top. For milk cartons, cut small holes or slits in the bottom and cut the container in half, but leave a hinge at the handle corner and remove the top cap. The pouring hole will provide the ventilation and allow for rainwater to enter. For cardboard orange juice containers, cut the box and remove the top portion. To create a top once planted, stand up two wood skewers. Attach the clear plastic bag to the container with tape or clothes pins. The tops of all containers should be clear to translucent.
Planting the Seeds
Unlike indoor seed propagation, there is more wiggle room in the timeline for winter sowing. To get a basic sense of the schedule, January is the perfect month to sow the perennial seeds that need a period of cold stratification, such as rudbeckia, delphinium and milkweed (Asclepias). I start hardy perennials that don’t need the freezing and thawing cycles in February and March, as well as cold hardy vegetables such as lettuce. Summer vegetables and annuals get potted the middle of March through April. Tomatoes are one of my favorite veggies to winter sow; and leeks, which require a long growing season, do wonderfully. Fill the prepared container with 3 inches of good potting soil and water thoroughly.
Sprinkle the seeds, pat down and either cover with soil or leave exposed, depending on the seed requirements.
Secure the lid depending on the type of container used. Cover smaller containers with plastic bags or plastic wrap. Duct tape works well on milk cartons and lasts through the winter.
Label the carton by either writing the name of the plant on duct tape with marker and taping to the bottom (which prevents fading) or on top with a Decocolor Paint Marker (which holds up to the sun).
Set the container into the garden and let nature do her work. If the weather is dry, supplemental water may be necessary. As the seedlings grow, create more ventilation in the lid.
Transplanting the Seedlings
After providing water and increased ventilation as the weather warms up, plant the seedlings into the ground at the same time greenhouse grown plants would be planted. No need to harden off.
Depending on how thickly the seeds were sown, there are several methods for planting. If thinly sown, gently remove each seedling and plant individually. If thickly sown, either use the Brownie method, removing the soil and seedlings in one clump and cutting the soil into bite-size pieces, or the Hunk-O-Seedlings, scooping out a spoonful of seedlings. Plant the hunk, and let the seedlings fight it out.
Due to some serious procrastination, I transplanted my last jug of leeks July 1st this last year, but had a bountiful harvest for soup, quiche and casserole. Tomatoes have been known to grow through the milk jug lid before I get them planted, yet go on to produce large, meaty fruit.
With winter sowing I’ve been able to grow and experiment with many varieties I would have been hesitant to try. My wintersown Passiflora incarnata climbs on the trellis (although it has yet to flower); Malva sylvestris mauritiana, Digitalis grandflora and Thalictrum rochebrunianum reach for the sky; hostas help fill the empty spaces; and poppies, Impatiens balfourii and Lychnis coronaria reseed with wild abandonment.
A version of this article appeared in print in Chicagoland Gardening Volume XXII, Issue I. Photography by Nancy Rosene.