Hello!
In an oddly warm here such as this 2024- should I start planting in MARCH the seeds that call for “as soon as ground can be worked”. Because the ground definitely feels like spring – even though it seems much to early!
Thank you for contacting Toronto Master Gardeners with this timely question, which is on many gardeners’ minds this year given the unseasonably warm weather – when to start seeds outdoors?
Gardeners organize their outdoor sowing (and indoor seed starting) keeping in mind the average last Toronto frost date is between April 30 and May 4. With warmer days, it is difficult not to be excited to seed outdoors “as soon as the ground can be worked”. However, this frost date is an average of the past – 50% of the time there is no frost after the average, while the risk of frost occurring 7 days later is 25% and with a 10% risk after 14 days.
Seeds/plants falls into 4 categories (please refer to your seed packets for direct sowing and indoor plant starting instructions):
1) Frost Hardy, sown April 1 – 15 (not usually damaged until the temperature drops to -2C at 1.5m above the ground): Asparagus, broccoli, Brussels sprouts, cabbages, lettuce, onions (set, seed, Spanish), radishes, rhubarb, peas, spinach, parsnips, early potatoes
2) Semi-frost Hardy, sown April 15 – 25 Beets, carrots, cauliflower, celery, late potatoes, early sweet corn.
3) Semi-frost Tender, sown May 1 – 15: Snap beans, sweet corn, tomatoes*
4) Tender, sown or planted May 20 – 30: Beans, cucumbers, eggplant, melons, peppers, pumpkins, squash
Besides frost risk, soil temperature* is another consideration when planting tender seedlings, (e.g. 15-18C for tomato plants). As the hardiness zones provides last frost dates for different zones, this chart should assist you in deciding when to start planting for indoor and outdoor seeding (see links): Southern Ontario & Greater Toronto Vegetable Planting Guide
For further general information, please see links: Climate zones and planting dates for vegetables in Ontario, Winter Sowing Seeds, Plant Hardiness Zone and Plant Hardiness Zone Canada
For additional indoor seed starting information, also see: Toronto Master Gardeners Guide.
Wishing you much gardening success and have a bountiful harvest.