Okay, good to have more detail. 6 two-inch heads is roughly equivalent to one large head. The plant is capable of supporting a limited amount of that growth, but it will survive the forecast. I would harvest half of the heads prior to the predicted low temperatures, and enjoy that for dinner. I would water after harvest with compost tea or some other hormone-rich low N supplement to help the plant recover. Cover the plant with a cardboard box if you are able to uncover it when the daytime temperature rises above freezing, otherwise use fabric, which will let some light through during the day. Plastic provides less insulation and magnifies the heating effects of sunlight, which you do not want. You could put a bottle of warm water under the cover as well, this will further stabilize the temperature. In a few weeks the remaining florets that you did not harvest will likely have reached a size that is worth a second harvest. Normal broccoli culture aims for one large head, but multiple small heads can equal the same yield. There is a point with most crops when the return won't justify continued effort, and you are better off starting fresh. You could leave one head on the plant to see if it will grow larger as the days get longer, you could cut off all of the florets and see if the plant produces more. or you could pull the plant and replace it with something that will give a more immediate gratification, like some salad greens.

Sounds like the plant is buttoning. It happens when the plant is stressed while young and it never fully recovers (it's a big problem with store bought transplants.) Without pictures, it's hard to determine. I run a website about gardening and have pages dedicated to broccoli. Check out the following link: http://www.vegetable-gardening-made-simple.com/growing-broccoli.html Surf through the broccoli pages. They have a lot of pictures of what you should be seeing as the plant grows and I actually used Packman broccoli the year I took the photos for these pages, so this should definitely be what you should be seeing if your plants are healthy. If your getting side shoots before you harvested the main head, then likely the plant is buttoning (sorry, I haven't had a chance to write about that yet so no pics for that.) If the plant is buttoning, it is still edible, just watch the heads and harvest them as you normally would, just realize they will be small. You won't get the 8 inch grocery store looking heads of broccoli. You can also harvest some of the leaves from the plants and eat those. They can be cooked up much like kale, spinach, or swiss chard. I have a recipe on the site for sauteed brussel sprout leaves that is delicious and you can substitute broccoli leaves instead for the same recipe. Good luck! ~Kelly Here is a link that might be useful: Vegetable Gardening Made Simple

Yeah, forget jonhughes posts! He's got veges on steroids! LOL Most of the broc you grow won't be quite that large and healthy. Farmerdill's photos look more like what I grow. It's hard to explain how they look when they're getting ready to flower. It's kind of like the buds "swell" and seperate. They aren't in such a tight head anymore (am I explaining this right?) As Wayne said, check them daily. They keep pretty well in the fridge, but are best fresh. Nancy

Broccoli will tolerate temperatures lower than 22F. It is about acclimation and they slowly become more tolerant to the colder temperatures in winter. I wouldn't use the row covers on them to protect from low temperatures; they may help more if used to keep it slightly warmer during the day so the plants will grow more in the winter. It usually gets down to about 10F each winter here and I haven't lost any Brassicas due to the cold. I also haven't had broccoli plants form the head when it is this cold as well. I either plant them early enough to harvest before it is this cold, or the plants overwinter and form a head in February or March. I usually only worry about the cold harming them when we get up to 70F and then drop back into the 30s and 20s the next day. They still hang on though.