How to Protect Broccoli Plants from Cold
Broccoli does best in cool conditions with temperatures between 60 and 70 degrees F. (16-21 C.). It can be damaged by a sudden heat wave or a sudden freeze. To keep the plants from being damaged by a late or early frost, allow the transplants to acclimate (harden) gradually to the outdoor temperatures. Transplants that have been hardened off will not be seriously damaged if the temperature drops down to 28 degrees F. (-2 C.). If temperatures are likely to get colder or last longer, you need to provide the plants with some broccoli plant protection. This can come in a number of forms. The plants can be covered with hotcaps, newspaper, plastic gallon jugs (cut the bottoms and tops out), or row covers. The delicious broccoli heads are much more frost sensitive than the actual plants. Frost damage causes the florets to get mushy. If this happens, cut off the head but leave the plant in the ground. More than likely, you will get some side shoots to form. If your broccoli heads are almost ready to harvest and temperatures are expected to dip into the 20s, cover the plants overnight with either a floating row cover or even an old blanket. Just be sure to remove the coverings in the morning.
Keeping Broccoli Safe from Pests
So, you have hardened off your transplants and planted them in nice fertile soil, spacing the plants 18 inches (46 cm.) apart to facilitate nice big heads, but now you see evidence of cabbageworms. Many insects like to dine on broccoli and keeping broccoli safe from these pests is no joke. Even birds get in on the feast by eating the cabbageworms. One way to protect the broccoli seedlings is to lay netting over supports, covering the plants. Of course, this keeps the birds out too, which isn’t a necessity. Row covers will also aid in protecting broccoli plants from the cabbageworms. If neither of these works or isn’t feasible because the plants have gotten too large, an application of spinosad, a biological pesticide, should do the trick. Another option is to use Bacillus thuringiensis, an organic insecticide. Flea beetles are tiny pests that are equally opportunity marauders. They can decimate a broccoli crop if they invade, especially during a steady warm period. Using organic fertilizers helps to deter them. You can also use trap cropping. This means planting vegetables that draw the attention of a pest. Basically, you sacrifice the trap crop, but save the broccoli! Try planting Chinese daikon or other radish varieties at 6 to 12 inch (15-31 cm.) spacings amongst the broccoli plants. Giant mustard may also work. The trap is a bit of a gamble, and the beetles may not be deterred. Also, if the trap works, you may have to reseed the trap crop, a small price to pay for saving the broccoli. Aphids will also get at your broccoli. With over 1,300 types of aphids, you’re bound to get an infestation somewhere. Once aphids are apparent, they’re hard to get rid of. Try blasting them off with water. This may take a couple of attempts and, in my experience, doesn’t get rid of all of them. Some folks say that laying aluminum foil down on the ground with the shiny side up will deter them. Also, laying out banana peels will purportedly repel aphids. You can spray the plants with insecticidal soap as well. This may take several applications. The best thing to do is to encourage ladybugs to frequent the garden. There’s nothing a ladybug likes quite as much as an aphid.
