Broccoli Growing Guide

This cool-season crop grows best when daytime temperatures are in the 60s F. Grow in both spring and fall, but avoid mid-summer crops as hot weather can cause premature bolting. Romanesco types are especially handsome choices for edible landscaping.

 

Site Characteristics

Sunlight:
„ full sun
Can tolerate light shade but will slow maturity.

Soil conditions:
„ requires well-drained soil. Prefers well-drained, fertile soil high in organic matter, pH 6.0 to 7.5. Can tolerate slightly alkaline soil. Needs plentiful, consistent moisture.

Plant Traits

Lifecycle: annual
Biennial grown as an annual.
Ease-of-care: moderately difficult
Requires good soil, timely planting and protection from pests.
Height: 2 to 3 feet
Spread: 2 to 3 feet
Bloom time:
„ early summer
„ mid-summer
„ late summer
„ early fall
„ mid-fall
Flower color: yellow
Foliage color: medium green. Some cultivars have a bluish cast.
Foliage texture: medium
Shape: upright
Tolerates:
„ Frost

Growing Information

How to plant:
Propagate by seed
Germination temperature: 45 F to 85 F - Will germinate at soil temperatures as low as 40 F.
Days to emergence: 4 to 7
Seed can be saved 3 years.

Maintenance and care:

Sow seeds indoors 6 to 8 weeks before average last spring frost. Keep soil warm (about 75 F), until germination. Then keep plants around 60 F. Provide direct sun so plants don’t get leggy. When plants are 4 to 6 weeks old, transplant into garden 12 to 20 inches apart.

Use wide spacings if you want to harvest large central heads. Closer spacings will produce smaller central heads. But if you harvest secondary heads you will get a greater total yield from the closer spacings.

Larger, older transplants are more likely to bolt when exposed to cool temperatures in the garden. Transplant when plants have four or five true leaves. Some cultivars will form small “button” heads when the weather turns warm following a 10-day stretch when high temperatures only reach the 40s F.

Can be direct-seeded as soon as you can work the soil. Will germinate at soil temps as low as 40 F. Plant ½ to ¾ inch deep, about 3 inches apart. Thin to final spacings. Direct seed in midsummer for fall crop, or start transplants in late May and transplant in late June or early
July. In Zone 7 and warmer, fall broccoli crops will often overwinter.

Use low nitrogen fertilizer at planting. Too much nitrogen fertilizer may cause hollow stems.
Plants have shallow root systems. Avoid even shallow cultivation. Mulch to protect roots, reduce weed competition and conserve moisture.

Use floating row covers to help protect from early insect infestations. To help reduce disease, do not plant broccoli or other cole crops in the same location more than once every three or four years.

Pests

Cabbageworms - Handpick and destroy. Row covers may be useful on small plantings to help protect plants from early damage. Put in place at planting and remove before temperatures get too hot in midsummer.
Flea beetles - Use row covers to help protect plants from early damage. Put in place at planting and remove before temperatures get too hot in midsummer. Control weeds.
Cabbage root maggot - White maggots (larvae) attack all plants of the cabbage family. Larvae tunnel in and feed on roots of plants. Damage causes wilting early on, death of plants a little later on.
Cabbage aphids - A hard stream of water can be used to remove aphids from plants. Wash off with water occasionally as needed early in the day. Check for evidence of natural enemies such as gray-brown or bloated parasitized aphids and the presence of alligator-like larvae of lady beetles and lacewings.
Other pests:
Slugs and snails
Cutworms

Diseases:

Clubroot - Locate new plants in a part of the garden different from previous year's location. If that is not possible, remove infested soil and replace with fresh soil. Purchase healthy transplants or start seed in sterile potting soil or fresh ground. Rogue plants. Remove and discard or destroy entire infested plant along with immediately surrounding soil and soil clinging to roots. If soil is infested, add lime to raise pH to 7.2.

Most popular cultivars are hybrids, though some open-pollinated cultivars are available. Cultivars mature at different rates, and some are best for fall crops. Choose several different maturity dates to spread out your harvest. Some cultivars tolerate heat somewhat and are best for summer harvests. Purple-headed cultivars are also available.

Varieties

The Italian cultivar ‘Romanesco’ is actually a cauliflower, though usually included with broccoli in seed catalogs.
“Broccoflowers” are a broccoli/cauliflower cross

Check out the extensive list of Broccoli Varieties here. You may find many you will love to grow and become your families new favorite or re-discover an old one.