Michigan’s frost dates set the planting and harvest window for collards, but soil temperature and winter lows decide whether they overwinter or end at first hard freeze.

Collards go into Massachusetts soil once the ground has warmed past the last frost risk, usually mid to late April near Boston and a bit later inland.

In most of Maryland, collards go into the ground once soil temperatures climb into the mid-40s and hold there, which typically lines up with mid-to-late…

Collard planting in Manitoba depends on soil temperature after the average May 23 frost date, and the region’s severe winter low makes it strictly a fall crop.

Collards go into Maine ground once the soil itself has warmed, not the morning the frost risk clears on a calendar.

Collards go into Louisiana ground twice a year in most parishes: a spring crop that beats the summer heat, and a fall crop that can keep producing…

Collards go in the ground here once the coldest nights have passed, and in much of Kentucky they can stay in the garden clear into winter, picked leaf by…

Collards handle Kansas better than most greens people try here: they shrug off the state’s brutal summer swings and keep producing right up to a hard…

Collards can go into Iowa gardens once the soil itself has warmed, not the moment the calendar says frost risk has passed.