Shelter from Cold
Freezing temperatures can cause chilling injury that turns buds purple and sometimes softens heads, though they are still good to eat. "I've had broccoli freeze solid, and when it thawed out it was fine," says Atina Diffley, co-owner of Gardens of Eagan Organic Farm, in Minnesota. Just don't let heads freeze and thaw repeatedly.
Offer cold-weather protection with floating row covers, which provide an additional 4 to 8°F worth of warmth, shielding harvests from heavy freezes and extending the season by up to four weeks. Or cover broccoli with tunnels or a coldframe, which can boost daytime temperatures by 10 to 30°F.
Protect Against Pests
Row covers provide some protection from pest insects, but the best protection is to grow healthy plants—and that begins with healthy soil, says Colby Eierman, director of gardens at COPIA: The American Center for Wine, Food & the Arts, in Napa, California. Insect pests are generally less prevalent in fall than in spring. But if your broccoli does suffer an infestation of destructive caterpillar pests such as cabbage loopers, you can control them with Bacillus thuringiensis var. kurstaki, a naturally occurring bacteria that stops the pests from chewing but is harmless to beneficial insects.
For best flavor, harvest broccoli heads while the buds are just starting to swell but before the yellow petals start to show. Keep an eye on the head, for when it begins to spread open, the individual buds start to flower. Harvest the central head by cutting the stalk at a slant, about 5 to 8 inches below the head. This encourages side-shoot production for continued harvests. Diffley says it's important to harvest broccoli in the morning before the plants heat up, because broccoli has a really high respiration rate. "Once the heat sets in, you need to cool it down quickly, or it's not going to hold up well and taste like it should," she says.
Now that you're set to grow the best-tasting broccoli ever, be sure to keep that flavor intact by not overcooking—broccoli is best when cooked until tender-crisp and still bright in color. In fact, Eierman says the chef at COPIA has a simple way of letting the flavor of broccoli shine: The florets are blanched and then shocked in an ice bath, then quickly stir-fried in olive oil. Of course, the best dishes begin with homegrown broccoli that's perfectly seasoned.