Here a very handy Seed Planting Guide From Little City Farm
For zone 5 to 6 in southern Ontario this is based on frost free date of May 24.
For more info, click here to see Karin’s full blog post on starting seeds & an upcoming workshop to learn more about starting your own seeds at home.
FEBRUARY (greens listed here can continue to be planted throughout the growing season)
Start lettuce, chard, other greens in greenhouse or in flats indoors (to be planted out to greenhouse). Start selected medicinal and culinary herbs by middle of February. Some take 6-8 weeks to germinate!
10 WEEKS TO LAST FROST (aprox. March 15)
Start seeds of celery, eggplant, leeks, onion, pepper and flowers like impatiens, lobelia, verbena and perennials indoors.
8 WEEKS TO LAST FROST (aprox. March 29)
Start seeds of early head lettuce and flowers like begonia, coleus, nicotiana, petunia, salvia indoors.
7 WEEKS TO LAST FROST (aprox. April 5)
Start seeds of tomatoes, hot peppers, and early basil indoors.
6 WEEKS TO LAST FROST(aprox. April 12)
Start seeds of early left lettuce, early cabbages including cauliflower, broccoli, brussels sprouts, kohlrabi and kale, and small seeded annuals indoors. DIRECT SEED broad beans, carrots, peas, spinach, leaf lettuce, turnips, dill, parsley, and hardy flowers such as alyssum, candytuft, pansies, poppies, snapdragons, stocks, sunflowers and sweet peas. Plant onion sets or transplant onion seedlingsoutdoors.
4 WEEKS TO LAST FROST (aprox. April 26)
Start melon seeds indoors. If desired, start seeds of late basil, cucumber, squash, pumpkin, large-seeded annuals, and flowering vines indoors in peat pots. DIRECT SEED radishes, beets, cabbages, chard, head lettuce, and flowers such as hollyhock, and mallow. Plant potato eyes and transplant seedlings of early cabbages, except cauliflower.
2 WEEKS TO LAST FROST (aprox. May 10)
DIRECT SEED corn, tender bulbs such as glads, and annual vines such as morning glory. Transplantearly lettuce seedlings.
WEEK OF LAST FROST (aprox. May 17-24)
Around the last frost date you can finally direct seed beans, cauliflower, cucumber, squashes, heat-loving flowers such as zinnias, marigold, and lavatera. Transplant your tomatoes. If you’ve got them, transplantcauliflower, squash and cucumber seedlings.
1 to 2 WEEKS AFTER FROST (aprox. May 31-June 7)
Wait for a couple of weeks after the last frost before direct seedling lima beans, soybeans, melons and herbs such as basil, summer savoury and sweet marjoram. Transplant celery, melon, peppers, eggplant seedlings when the night temperatures stay well above 10 degrees C. Plant sweet potato slips. Start second crop of kale seedlings, reseed spinach and peas for second crop.