Plant Brussels sprouts so that they come to harvest in cool weather.
Planting Calendar. Brussels sprouts are best grown in cool weather, usually in early spring or autumn. Sprouts require from 80 to 110 days with daylight temperatures below 80ºF (27ºC) and nighttime temperatures even lower. Brussels sprouts are frost hardy and will tolerate temperatures as low as 20ºF. A frost will sweeten the flavor of Brussels sprouts. Temperatures that are either too cold or too warm for too long will cause Brussels sprouts to taste bitter. Sprouts that develop in hot weather may not form compact cabbage-like heads. Where winters are mild, Brussels sprouts are best grown in late fall or winter.
• Spring crop. Sow seeds 4 to 6 weeks before the average last frost date in spring or sow directly in the garden 2 weeks before the last frost.
• Autumn and winter crop. Where summer and fall is not too warm, sow Brussels sprouts seeds about 90 days before the first frost date. In mild-winter areas, Brussels sprouts can be planted in autumn for winter harvest.
Place. Brussels sprouts prefer full sun but will grow in light shade.
Soil. Brussels sprouts prefer well-worked, well-draining soil rich in organic matter. A sandy loam soil is ideal. Work plenty of compost into the garden before sowing seed or setting out transplants. Where the soil is sandy, work compost in before planting and side dress seedlings and plants with compost a couple of time during the growing season. Brussels sprouts grow best in neutral soil with a pH within the 6.5 to 7.5 range.
Spacing. Sow Brussels sprouts seeds ½ inch deep and about 2 inches apart. Later thin 3-inch-tall seedlings to about 20 to 30 inches apart in a wide bed or block. Rows should be 24 to 36 inches apart. Seedlings started indoors can be planted out when they reach about 5 inches tall, usually at about 4 to 6 weeks old. Transplants with leggy or crooked stems should be planted up to their first leaves so they won’t grow spindly and top heavy.
Container growing. One Brussels sprout–which can produce two to three pounds of sprouts–will grow in an eight-inch flower pot. Allow 20 to 30 inches between plants in larger containers.
Water. Keep Brussels sprouts well watered particularly in dry or hot weather. Adding plenty of compost to your soil will help retain water.
Feed. Keep the ground around Brussels sprouts well composted. Brussels sprouts need calcium; you can add crushed egg shells to the soil around Brussels sprouts. Side dress Brussels sprouts with rich compost at midseason or more often.
Suggested varieties. Captain Marvel (78 days); Prince Marvel (83 days); Jade Cross (90 days).
More tips at How to Grow Brussels Sprouts.