Reverse it? Not really. You can try cutting off the top leaving about 1 1/2" of stem below and re-rooting it. But usually once it begins to bolt it will just keep right on bolting.

Different varieties bolt faster than others, some varieties tolerate warm soil temps better than others, some varieties tolerate age/size differences in the transplant better than others. Bigger the transplant the more likely it is to bolt.

If you have some that are already forming heads then I would think it may have been still way too warm when they were planted for your zone and warm soil and warm air temps leads to fast bolting. We are just now planting fall cabbage in our garden.

Dave

If you are talking long stems, not bolting they may head out just fine. It was common years ago to have long stem cabbage. If you read a pre WWII seed catalogue you will see varieties touted as short stem. The major disadvantage to long stems is the head will fall over sideways especially with larger varieties.

There is a possibility they are off type. I bought some broccoli seedlings to supplement the ones I grew myself, and two of them have turned out to be Romanescos rather than Premium Crop. Not complaining.

My guess would be that some of the plants you bought at the nursery were in good shape, while others were root bound or otherwise defective. Nurseries are motivated to sell what they have, even if it is of terrible quality. You have to remove some of the plants from their medium (pots, trays, etc.) to check their roots. If there is any sign or bolting or being root-bound, do not buy the plant. Once a plant starts bolting, there is no stopping it. Cutting it back will do no good. The best solution is to start your own seeds, if possible. A good introduction to seed propagation can be found at the website below.

Alan Chadwick

Click on "Techniques" and then choose your subject. These methods are based on those of Alan Chadwick, who brought organic gardening to the USA in the 1960's and 1970's.

Here is a link that might be useful: Alan Chadwick