Vegetable · Brassicaceae
Brussels Sprouts
Brassica oleracea Gemmifera Group
Plant them for fall and let a light frost finish the job, and the sprouts arrive firm and sweet.
Full sun
Every 3–7 days
41–77°F · 5–25°C
80–110 days
Overview
Brussels sprouts belong to the cool-season cabbage family, the very same species as broccoli, kale, and cauliflower, each one shaped into a different form by generations of growers. The plant throws up a tall, sturdy stalk studded with dozens of small cabbage-like buds, and those buds are the sprouts you harvest. It is a biennial grown as an annual, picked in its first season long before it would ever bother to flower.
Patience pays off with this crop. Brussels sprouts grow slowly and need a long run of cool weather to hit their stride, so gardeners time them to mature in fall rather than the summer heat. Cold actually improves them, turning starch into sugar so the sprouts taste sweeter once the first light frosts arrive.
They want steady care across a long season: rich soil, even moisture, and a guard against the cabbage pests that track down every brassica in the garden. Nail the timing and feed them well, and a single stalk keeps handing you harvests for weeks, working from the bottom up.
Care
The short version: give them full sun and rich, evenly moist soil, time the planting so the sprouts mature in cool fall weather, feed them steadily through a long season, and keep a sharp eye out for cabbage pests.
Light
Brussels sprouts crave full sun, ideally 6 or more hours a day, to build the strong stalk that hauls a heavy crop. They put up with a little partial sun, but real shade leaves you with weak plants and loose, disappointing sprouts.
Water
Keep the soil evenly moist right through the long season, around 1 to 1.5 inches (2.5 to 4 cm) of water a week. Bouncing between bone dry and soaking stresses the plant, so spread mulch to lock in moisture and keep the roots cool.
Soil
Plant into rich, well-drained loam packed with organic matter, since these hungry plants hold the ground for months. Aim for a pH between 6.0 and 7.0, and lean toward the higher end, which also helps hold clubroot at bay.
Temperature
Brussels sprouts are a cool-weather crop that runs best from roughly 41°F to 77°F (5°C to 25°C). Hardened plants brush off frost and stand in the garden until temperatures dip toward 20°F (-7°C), and that cold is exactly what sweetens the sprouts.
Humidity
Ordinary outdoor humidity suits them, so skip chasing a number. Good airflow counts for more than moisture in the air, since crowded, damp foliage invites the diseases that plague brassicas.
Feeding
These are heavy nitrogen feeders. Work a balanced fertilizer into the bed at planting based on a soil test, then start side-dressing with nitrogen about 3 to 4 weeks after transplanting and keep feeding through the growing season to keep sprouts coming.
Pruning
Pull the lower leaves as they yellow and the sprouts below them mature, working your way up the stalk. About 3 to 4 weeks before you want to harvest, pinch out the growing tip to drive energy into the sprouts that remain so they size up evenly.
Size & spacing
A mature plant rises 2 to 4 feet (60 to 120 cm) tall and spreads about as wide. Space transplants 18 to 24 inches (45 to 60 cm) apart so air moves freely between the big leaves and disease stays down.
When to plant
Brussels sprouts are built for the back half of the year. Start the seeds in late spring, move the plants out in early to midsummer, then harvest from early fall into winter, picking the firm sprouts from the bottom of the stalk upward as the cold sweetens them.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Sow indoors 6-8 weeks before transplanting; in cold-winter regions sow in late spring (May-June) so plants mature as a fall crop, or 4-6 weeks before the last spring frost for an early planting
- Plant: Transplant hardened seedlings in early to mid summer (late June-early July in northern gardens) for fall harvest; in mild-winter regions plant in late summer for winter harvest
- Harvest: Harvest from early fall into winter, picking firm 2.5-4 cm sprouts from the bottom of the stalk upward; flavor sweetens after light frosts and plants can stand in the garden until temperatures drop toward 20°F
Hardiness
USDA hardiness zones: 2–9
Temperature: down to -46°C
Troubleshooting
Most Brussels sprouts trouble comes back to timing, feeding, or the relentless push of cabbage-family pests. Spot the early signs on the leaves and roots and you can usually stop a problem before it climbs the stalk. Match what you see below, then act while it still does some good.
Plants wilt in the heat with swollen roots
Clubroot is a soilborne disease of cole crops that takes hold in acidic, soggy ground, and it shows as wilting on warm days and stalled growth. Lift a failing plant and you'll spot the giveaway swollen, club-shaped galls along the roots. Nothing cures it once it settles in, so pull infected plants roots and all, lime the bed toward pH 7.0, and shift your brassicas to clean ground.
Fix:
- Remove and destroy infected plants including roots; do not compost them
- Lime soil toward pH 7.0 or slightly above to suppress the pathogen
- Move brassicas to a clean bed
Loose sprouts that flop open and never tighten
Blown, open sprouts point to heat far more often than to anything in your soil. Buds that form in summer warmth instead of crisp fall air swell loose and leafy, and a late hit of nitrogen drives them looser still. Push your planting later so the sprouts bulk up in cool weather, then top the plant 3 to 4 weeks before harvest to tighten the buds that are left.
Fix:
- Time plantings so sprouts develop in cool fall weather
- Harvest loose sprouts promptly and use them; they remain edible
- Top the plant 3-4 weeks before harvest to firm up remaining sprouts
Powdery gray aphids crammed into the sprouts
Cabbage aphids multiply fast on brassicas when the weather turns warm, then burrow deep between the sprout leaves where they dodge a casual spray. Flip the leaves and look for dense, mealy gray colonies, curling foliage, and sticky honeydew. Knock them loose with a hard jet of water, coat the undersides thoroughly with insecticidal soap or horticultural oil, and strip away any lower leaves that are crawling with them.
Fix:
- Knock colonies off with a strong spray of water
- Apply insecticidal soap or horticultural oil with thorough coverage of leaf undersides
- Remove and destroy heavily infested lower leaves
Ragged holes in the leaves with green droppings below
Three caterpillars chew this kind of damage, and they often feed side by side: the imported cabbageworm, the back-arching cabbage looper, and the small, squirming diamondback moth larva. Turn the leaves over and hunt for green caterpillars and frass, and keep an eye on the white butterflies dropping cabbageworm eggs. Pick off what you find, spray Bt or spinosad while the caterpillars stay small, and drape the plants in floating row cover to lock the moths out.
Fix:
- Handpick caterpillars
- Apply Bacillus thuringiensis (Bt) or spinosad while caterpillars are small
- Cover plants with floating row cover to exclude egg-laying moths and butterflies
Toxicity
Good news for pet owners: Brussels sprouts are a food crop and safe to grow around cats, dogs, and other animals. The plant is not toxic, and the worst a curious nibble brings on is a bit of gas. Cook them before serving people, since a steady diet of large raw amounts is the only real catch.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Perfectly safe company. A nosy cat that nibbles a leaf might turn a little gassy, but nothing in the plant can hurt it.
Dogs None
Nothing to worry about. A dog that wolfs down a big helping of raw sprouts may get flatulent or briefly upset in the gut, and that's as bad as it gets.
Horses None
Not toxic to horses. Brassica greens can stir up some gas in bulk, so offer them as an occasional nibble rather than a regular feed.
Rabbits None
Fine for rabbits in small amounts. Bring the leaves in gradually, because a sudden pile of any cabbage-family green can loosen their digestion.
Livestock None
Cattle, goats, and sheep can graze the foliage just fine at normal levels. Only steady, heavy raw feeding raises any flag.
Birds None
Backyard hens love pecking at the leaves and trimmings with no trouble at all.
People Safe
Grown to eat and genuinely good for you. The sprouts shine cooked, and only a steady diet of large raw amounts would matter for thyroid health.
No special handling precautions; wash before eating as with any garden produce.
Varieties
Brussels sprouts come in a handful of dependable varieties, from old heirlooms to colorful modern hybrids. Here are the ones worth knowing by name.
Long Island Improved
A classic open-pollinated heirloom on a fairly compact plant that home gardeners reached for generation after generation.
Jade Cross E
An early hybrid that takes heat in stride and crops heavily, a smart pick where the fall season runs short.
Falstaff
A late variety with red-purple sprouts that hold much of their color right through cooking.
Companions
Brussels sprouts do best beside plants that mask their scent from cabbage pests, and worst beside a few crops that simply don't get along with the cabbage family.
Plant near
onions: WVU Extension lists the onion family as compatible with cabbage-family crops; alliums' strong scent helps mask brassicas from common pests
aromatic herbs (sage, rosemary, peppermint): WVU Extension lists aromatic herbs such as sage, peppermint, and rosemary as compatible with the cabbage family; their scents help confuse and deter cabbage pests
beets: WVU Extension lists beets as compatible with cabbage-family crops; the low-growing roots share space well beneath tall brassicas
Keep apart
strawberries: WVU Extension lists strawberries as incompatible with cabbage-family crops and recommends keeping them apart
How to propagate
Brussels sprouts grow from seed, started indoors and set out as transplants once they're big enough to fend for themselves.
SeedEasy
Sow indoors 6-8 weeks before transplanting (late spring in cold-winter regions for a fall crop); seeds can also be direct-sown about 4 months before the expected first fall frost · Germinates in about 5-10 days; seedlings reach transplant size in 4-6 weeks
Brussels sprouts spring up readily from seed. Tuck them about a quarter to half an inch (0.6 to 1.3 cm) deep in sterile starting mix 6 to 8 weeks before your transplant date, and the seedlings push through in 5 to 10 days and reach planting size in 4 to 6 weeks. Harden them off, then set them out 18 to 24 inches (45 to 60 cm) apart at the same depth they grew in their pots.
Myths
Brussels sprouts must be hit by a hard freeze before they are worth harvesting.
The plant needs no freeze whatsoever, and any firm sprout is ready for picking. Cool fall weather and light frosts do sweeten the flavor by building up sugars, which is exactly why the crop is timed to mature in fall. You can pick plenty of fine, tight sprouts well before the first frost.
Cutting the top off a Brussels sprouts plant ruins the crop.
Topping is a clever move, not a blunder. Pinching out the growing tip 3 to 4 weeks before harvest halts the upward climb and redirects the plant's energy into the sprouts already on the stalk so they fill out more evenly.