I live in Laingsburg MI , in Shiawassee Co. .How can we tell when it is time to harvest our cabbage? I expected to wait untill the end of summer normally. I am wondering if we need to harvest sooner as one cabbage already split open as it grew. Is there some resource of a harvest schedule for home gardening for our County or Mi?
Your cabbage cracked because it was growing too fast due to favorable temperatures and all the rain you have had recently. Cabbage harvest depends on when it was planted, how long it takes the variety to mature and the intended use.
Cabbage harvest starts in July and can continue into November depending on when it was planted. A 90 day to maturity cabbage can be planted from mid-April through August 1 for harvest July through October simply by staggering the planting times.
There really isn't a harvest guide that is as specific as you suggest. The best thing to do is to go by the days to maturity information that comes on the seed package or transplant tag.