Buttoning is one way cole crops respond to stress.
There are many types of stress that can cause buttoning:
These stress factors trigger plants to start reproductive efforts before they is actually ready, causing small leaf size, stunted overall growth, and misshapen flowers. These conditions also increase the likelihood of pests and diseases over the winter months.
Buttoning in cole crops
Broccoli and cauliflower exhibit buttoning by producing smaller than normal heads. Buttoning of cole crops is more common among transplants, so direct seeding may be preferable if stresses are expected. Mature plants can tolerate the cold, but young plants and seedlings exposed to a few days of 35 to 50°F temperatures can alter the vegetative growth, leading to buttoning. Cabbage is not prone to buttoning.
How to prevent buttoning
Selecting the right varieties for your microclimate and planting at the proper time are the two best ways to avoid buttoning. Maintaining a regular watering and feeding schedule, and mulching around plants, can keep them strong enough to handle short term stress.
I hope this information inspires you to grow more of your own food. You can ask your garden questions on my Home page.