Once the snow has melted, and the soil is workable (that is, it is neither frozen, cold, or very wet), you may direct sow cool season crops. These plants tolerate overnight temperatures that hover around the freezing mark, and even a touch of frost; they prefer the cool temperatures of spring and fall rather than the heat of summer, during which they may bolt (go to seed too quickly).
Refer to the seed package to see how many weeks prior to the last frost that you may sow the seeds. The package may also list an ideal soil temperature. You may choose to place row covers over the area that you are planting to expedite the warming of the soil and protect your plants from occasional cold nights.
The following plants are quite hardy, and can tolerate a soil temperature of around 5°C:
- Spinach, lettuce, collard greens, kale, kohlrabi, and other greens
- Turnip and rutabaga
The following plants are also quite hardy, though they prefer a slightly warmer soil temperature of around 10°C:
- Broccoli (shown above), Brussels sprouts, cauliflower, and cabbage
- Onion sets