Brussels Sprouts

Growing Conditions

Brussels sprouts need a long, cool growing season — 90 to 110 days from transplant, with cool temperatures throughout. They are grown almost exclusively as a fall crop in most of North America, planted in summer for harvest after the first frosts. Temperatures between 60°F and 70°F produce the tightest, best-flavored sprouts. Frost is beneficial — it converts starches to sugars and significantly improves flavor.

Cold climates (Zone 5 and colder): Start indoors in late spring (May–June) for fall harvest. Transplant in July. Expect harvest from October through December with row cover protection.

Warm climates: Brussels sprouts are difficult in regions where fall doesn’t bring sustained cool temperatures. They’re a better choice for climates with a genuine cool fall.

Sowing & Planting

Start indoors ¼ inch deep, 4 months before first fall frost. Transplant when seedlings are 6 weeks old. Space 24 inches apart in rows 30 inches apart — Brussels sprouts are large plants. Stake tall plants in windy locations.

Some growers remove the growing tip (top of the main stalk) in late summer to encourage sprouts to size up simultaneously rather than producing over a long period. This is optional but useful if you want a concentrated harvest.

Care & Maintenance

Consistent moisture is important throughout the season. Brussels sprouts are heavy feeders — side-dress with compost or balanced fertilizer monthly. Mound soil around the base of plants if they begin to lean. Remove yellowing lower leaves as the season progresses to improve air circulation.

Common Problems

Cabbage worms are the primary pest — use Bt or row cover. Aphids can be severe, particularly on plants stressed by heat or drought. Loose, bitter sprouts result from heat during the growing season — this is a timing problem, not a pest or disease issue. Clubroot prevention requires 3-year rotation and pH management.

Harvest

Harvest sprouts from the bottom of the stalk upward as they reach 1–1.5 inches in diameter. They should be firm and tightly closed. Loose or open sprouts are past their peak. After frost, flavor improves — wait for at least one good frost before beginning harvest if possible. A single plant can produce 50–100 sprouts over the harvest season.

Varieties

Shorter-season varieties (Jade Cross, Churchill) are better suited to climates with shorter cool seasons. Standard varieties (Long Island Improved) suit most home gardens. Hybrid varieties tend to be more uniform and disease resistant than open-pollinated types.