Hi. I intended to winter sow earlier this year (as my older, colder, darker house and I tend to produce leggy and sometimes deady seedlings), but here we are already! What plants would be suitable for winter sowing now (Apr 7)? I have seeds and am interested in (arbitrarily): chinese cabbage, okra, garlic? chive, cukes, nasturtium, kale, tiny thom peas, marigold, zinnia, poppy, morning glory, cherry/sungold/grape toms, ground cherry, lettuce, arugula, zucchini, beet, green/red pepper, gai lan, cilatnro, dill. Thank you!
Winter sowing is the strategy of planting seeds in containers during winter months and placing these outdoors until seedlings emerge in spring. Cold hardy vegetables, perennials and native plants are the most suitable for this process. The containers remain outdoors until the seedlings emerge in the spring. The container protects the seeds and allows a brighter light than may be obtained indoors without artificial lighting. The best time to winter sow cold hardy plants is from December to March while tender plants may be sown in March to April.
Considering your list and assuming your hardiness zone is Zone 6, your cold hardy seeds (arugula, Chinese cabbage, gai lan, kale, tiny Tom Thumb peas, cilantro and lettuce) are best to direct plant in your garden at this time (Apr. 7). Semi-frost hardy beet seeds should be direct planted from Apr 25-May 10.
Semi-frost tender tomato seedlings can be transplanted to the garden around May 15-25 as long as the soil is warm with night temperatures above 10C. You might wish to experiment with “winter sowing” your tomato seeds right away – the seedlings may be large enough to transplant toward the end of May to early June. Tomatoes and peppers are heat loving, necessitating that the containers be brought indoors on cold nights. A consideration to be mindful of is the dates to harvest to ensure that there is enough time from seeding to harvesting ripe fruit. You might also experiment with winter sowing zinnia, nasturtium, marigold and ground cherry seeds now and transplanting these to the garden in mid-late May. Alternatively, direct sow marigold, nasturtium and zinnia seeds starting May 1, May 15, and June 1 respectively. Please consult your seed packets for specific guidelines.
Poppy seeds are direct sown mid-April as they do not tolerate transplanting. The seeds of your frost tender plants, cucumbers, okra, zucchini, chives, dill and morning glory should also be direct sown around May 25-June 5 as their roots likewise do not tolerate disturbance well. Garlic is direct sown in the garden or planters in mid-October.
For further information, please click on the following links:
March: Calculating the Sowing Date
Growing From Seed: A Toronto Master Gardener Guide
Regional Planting Chart for Ontario: Planting Vegetables, Southern Ontario & GTA
Wishing you much success in your adventure with late winter sowing.
10/04/23