Brussels Sprouts

Brussels sprouts, a member of the Brassicaceae (cabbage) family, had their origins in the Mediterranean region but received their familiar name only after they were widely grown in Belgium. They do best in coastal regions where they are grown commercially in California.

Basics

Growth is best in Sonoma County in cooler areas along the coast.
Provide well-drained, fertile soil for sowing in beds or transplanting.
Start seeds in pots or flats July-August and transplant out when plants are 7-8 weeks old.
Set plants 15-24 in. apart, closer for short-season types, farther for long-season types.
Plants set out in mid-summer are harvested in fall-winter. Allow 80-100 days or longer until maturity for shorter-growing, short-season varieties, and 100-150 days for long-season varieties.
Cover planting beds between stems with compost or organic mulch. Irrigate in the absence of rains but do not overwater.

Growth Habit and Harvesting

Expect an early harvest with ‘Long Island Improved’ and ‘Prince Marvel’ varieties and more heat tolerance with ‘Jade Cross’.
Look for small cabbage-like sprouts clustered around the central stem just under each leaf.
Pick mature sprouts closest to the bottom, usually smaller in maturity than those higher up. Sprouts mature gradually from the bottom upward.
Break away leaves on stems, then remove firm, golf-ball-size sprouts no more than 1-2 in. in diameter, either green or purple, depending on variety.
Leave very small sprouts on top areas of the stem to further mature. Expect 50-100 per stem.
Harvest over several weeks, possibly months. Days or nights of frost will sweeten flavors.

Possible Problems

Soil-borne diseases and insect pests are more common if Brussels sprouts are planted in areas where other cabbage (cole) family crops have been grown. Crop rotation is best.
Wait for optimal planting time in mid-summer. Spring plantings expose Brussels sprouts to hot summer temperatures that will cause stems to bolt before fruiting.
Prevent wet foliage by using drip irrigation to maintain evenly moist soil, never overwatered.
Avoid allowing soil to dry out completely, resulting in stronger, unpalatable flavor and odors.
Keep an eye on developing small sprouts. If they form loose tufts of leaves instead of firm sprouts, they probably developed during weather that was too hot.
Cover transplants with floating fabric row covers to exclude pests such as caterpillars and loopers, and army worms. These and any harlequin bugs may be removed by hand.
Watch for aphids; spray them immediately with a strong jet of water if any appear.

Additional Information

February 2022