May is the perfect time to plant most vegetables. However, the exact timing depends on whether a vegetable plant can withstand cool temperatures and whether it will thrive in warm temperatures. Hot crops are plants that generally thrive in hot temperatures and cannot survive sustained cool temperatures. Hot crops should be planted when nighttime temperatures (both now and forecasted) exceed 10oC. Here in southern Ontario, this usually means we can plant hot crops outdoors starting in mid-to-late May.
Hot crops include (but are not limited to) the following:
- tomatoes *
- eggplants *
- peppers *
- sweet potatoes
* start these plants indoors in March
Most hot crops can be seeded directly into your garden, except for a few veggies that MUST be started indoors due to our Canadian climate. Crops such as tomatoes, peppers, and eggplants need 90-110 days to produce ripened fruit and they will continue to produce after that if the weather stays warm. Weighing this against the 110-120 days of ideal weather for hot crops each year in southern Ontario, you either need to plant them early, or else start them indoors to reliably harvest more than one flush of veggies.
For those that can be direct-seeded, watch for any unexpected drops in temperature after seeding and be sure to protect the plants from any unseasonably cold nights.