Zones 3 and warmer
Grow as a winter crop in mild-climate areas. Where springs are cool, you may grow as a spring crop, otherwise does best in cool weather in the fall
Climate Zones Maps
Full sun, partial shade will reduce head size
Well-drained with plenty of calcium; prefers pH 6.0 to 6.8, but will tolerate pH up to 7.2
Regular water, keep soil evenly moist, but not wet
Plant 12 to 24 inches (30 to 60 cm) apart; wider spacing will yield larger heads, and leave 2 to 3 feet (.61 to 1 m) between rows
Harvest broccoli heads when they have reached maximum size, are still compact, and before the buds loosen, open into flowers, or turn yellow
Planting Site: Broccoli needs full sun; partial shade will reduce head size. To minimize disease, allow three years between plantings of broccoli and other cabbage family plants (cabbage, kale, cauliflower, and Brussels sprouts). Broccoli is a heavy feeder and it thrives being planted in an area where previous crops were legumes such as peas or clover.Helpful Articles: The Wonders of Mulch - A Complete How To Use Mulch Guide
Planting & Growing Guidelines: There are early, middle and late cultivars to choose from. Hybrids tend to be more productive than open-pollinated cultivars. If you've had problems in the past, choose cultivars that are tolerant to problems like hollow stem, black rot, and downy mildew. In the spring, you can start seedlings indoors about 2 months before the last spring frost, and set out hardened-off transplants in the garden a month before the last frost. In the fall, sow crops directly into the garden about 90 days before the first fall frost (Example: sow seeds in August for a late crop in October or later), or transplant seedlings about 60 days before the first fall frost. Direct sowing is only an option for fall plantings because the soil temperature is over 50° F (10° C), but the air is cool (between 60° and 75° F (16° to 24° C). Broccoli seedlings are very vulnerable to excess heat (anything over 80° F (27° C)) which will dry them out and result in little to no production of a head. Cultivate or mulch to keep the soil evenly moist. Lack of water will stress the plant and can lead to its not forming a head, or making it more vulnerable to insects and pests. Excess water will stunt or kill it. If your soil tends to get waterlogged, plant in raised beds.
Mulching - How Much And How Deep?
Fertilizer: Lightly broadcast some 10-10-10 over the area, till in, and then plant transplants or sow seeds. When the plants start to form a head, side-dress with 1 tablespoon (15 ml) per plant of 5-10-10, or one large handful of good compost which generally equals the same. Sprinkle around the base of the plant, but not up against the stem, and water in.
Pest and Disease Prevention: Use cardboard or metal "collars" to deter cutworms. Row covers will help deter flea beetles, cabbageworms, and root maggots. Spray or dust with Bacillus thruingiensis if cabbageworms are a problem. To avoid soilborne diseases, don't plant broccoli or other cabbage-family plants (cabbage, kale, cauliflower, and Brussels sprouts) in the same spot more than once every three years. Cold, rainy weather can bring on diseases that cause heads to rot, planting cultivars with dome-shaped heads helps since water drains off more quickly.
Helpful Articles: Cutworm
Heavyweight Row Covers
Common Problems: In some areas, spring broccoli will bolt (go to seed early) at the beginning of hot weather. Choose quick-maturing cultivars and expect spring grown broccoli heads to be smaller then those grown in the fall.
Days to Maturity: 70 to 95 days.
Harvest and Storage: Harvest broccoli heads when they have reached maximum size, are still compact, and before the buds loosen, open into flowers, or turn yellow. Spring crops should be harvested once with as much of the edible stem as possible. Cut fall heads with less stem attached, leaving as much of the plant intact as possible to produce smaller sideshoots or "florets," which you can harvest until a hard freeze. When you bring broccoli indoors, soak the heads in lightly salted water (1 to 2 tablespoons (15 to 30 ml) of salt per gallon (4 l)) for 30 minutes before cooking or storing. This will drive out any cabbageworms hiding in the heads. Broccoli will keep in the refrigerator in a plastic bag for 7 to 10 days and can be eaten fresh, and it freezes well for future use.
Special Tips: Where temperatures stay above 40° F (4.4° C) broccoli will grow all winter.