The rule of thumb for vegetable planting season is to start vegetable seeds 6-8 weeks prior to the last expected frost, but refer to the seed pack for specific instructions.
There are 150-170 frost-free days in London, Ontario area, according to data from the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), and May 3 is the average date of last frost. As the OMAFRA website has mentioned, this date listed in indicates that 50% of the time (one year in two) there will be no frost in this location after that date and there is a 25% risk of a frost occurring seven days after the listed last spring frost date. Fourteen days after the listed date, the risk decreases to 10%. Conversely, there is a similar risk factor associated with frost occurring before the first fall frost dates.
In this vein, at Van Luyk’s our general rule of thumb is May 24. But that doesn’t mean you can’t still purchase your plants earlier and let them toughen up by placing them outside during the day and bringing them inside at night if frost threatens.
To give a clearer calendar for vegetable planting season in London Ontario region, we divide our vegetable selection into three broad categories: hardy, semi-hardy, and tender.
Hardy Vegetables
Hardy vegetables tolerate hard frosts (usually -4 to -2 degrees C). They are good for spring and fall gardens. The hardiest -– kale, spinach, and collards –- can tolerate temperatures between -5 and -8 degrees C. All of them taste best when they mature in cool weather, so they are also very well suited to late summer planting for fall harvests.
- Broccoli
- Brussels sprouts
- Cabbage
- Collards
- English peas
- Kale
- Kohlrabi
- Leeks
- Mustard greens
- Parsley
- Radish
- Spinach
- Turnip
These plants can be planted between April 15 and 25.
Semi-Hardy Vegetables
Semi-hardy vegetables tolerate light frosts (usually -2 to 0 degrees C) late into fall and through winter in mild climates. They are good for spring and fall gardens.
- Beets
- Carrot
- Cauliflower
- Celery
- Chinese cabbage
- Endive
- Seed Potatoes
- Lettuce / Gourmet Salad Greens
- Radicchio
- Rutabaga
- Swiss chard
These plants can be planted in late April and early May.
Tender Vegetables
Plant these vegetables in high spring, after the threat of frost has passed. These tender vegetables need warm weather (18 to 31 degrees C) to grow and are killed by frost. They are for summer gardens only.
- Beans
- Corn
- Cucumber
- Eggplant
- Gourds
- Melons
- Okra
- Peppers
- Pumpkins
- Summer squash
- Sweet potatoes
- Tomatoes
These plants should be planted after May 24-25.
Happy Spring!