Vegetable · Brassicaceae
Broccoli
Brassica oleracea Italica Group
Set for cool weather and steady moisture, broccoli earns its place with a main head and weeks of side shoots.
Full sun
Every 3–5 days
32–77°F · 0–25°C
55–85 days
Overview
Broccoli is the cool-weather aristocrat of the cabbage family, grown for the tight cluster of flower buds gathered before they ever open. Descended from wild cabbage, it keeps company with cauliflower, kale, and Brussels sprouts in the same species. Treated as an annual, it slips easily into a spring planting, a fall planting, or both across one season, the backbone of a well-kept potager.
The rhythm of the year shapes everything. Plants set out to mature in cool weather give you the firm, handsome head that anchors a Sunday roast or a winter soup, while heat opens the buds into yellow flowers and ends the season early. Time it well and the reward extends past that first cutting, with side shoots for the kitchen from the leaf axils week after week.
There is a certain ease to broccoli that suits a busy household. A heavy feeder content with rich soil, even moisture, and full sun, it asks only for a steady hand and a length of row cover against its familiar pests. Meet those few needs and it becomes one of the most giving residents of the garden, a fixture in the cook's calendar.
Care
The short version: full sun, rich soil generous with compost, and even moisture of 1 to 1.5 inches of water a week. Plan the crop so the heads mature in cool weather, feed it well, and cut the head while the buds are still tight.
Light
Broccoli wants a place in full sun, at least 6 to 8 hours a day, to set a firm head worth bringing indoors. Where springs warm quickly, a corner with light afternoon shade serves it well, and that shade can stretch the season a little before heat tips it into bolting.
Water
Keep the bed evenly moist, around 1 to 1.5 inches of water a week. A single deep soak does more than a scatter of light sprinklings, and that steadiness counts most while the head is forming, when a dry spell would stall it just as the kitchen is waiting.
Soil
Give it rich, well drained loam turned through with compost or well-rotted manure, the kind of ground a productive kitchen garden is built on. A pH of 6.0 to 7.0 suits it, and the near-neutral end keeps clubroot at a distance, since that trouble favors sour soil.
Temperature
Broccoli is a cool-season crop, at its best from 32°F to 77°F (0°C to 25°C). It takes a light frost gracefully, but sustained heat above about 80°F (27°C) sends the head to bolt before it ever reaches the cutting board.
Humidity
Ordinary outdoor humidity asks nothing of you, so there is no figure to meet. Airflow is the thing to plan for, since a crowded, damp planting invites the caterpillars and rots that shadow brassicas.
Feeding
Broccoli is a heavy feeder with a real appetite. Work a balanced fertilizer into the bed before planting, then side-dress with nitrogen about 3 to 4 weeks after transplanting to carry strong leaf growth ahead of the head.
Pruning
There is no real pruning to keep up with. Cut the central head with about 6 inches of stem while the buds stay tight, leave the plant in place for the side shoots to follow, and tidy away any lower leaves that yellow.
Repotting
Broccoli is no houseplant, so repotting never enters the picture. Move seedlings into the garden at 5 to 8 weeks old, before they grow rootbound, since cramped transplants are inclined to button once they settle in.
Size & spacing
Plants stand 18 to 35 inches (45 to 90 cm) tall and spread to match. Set each one 18 to 24 inches (45 to 60 cm) apart so air drifts through the row and every plant has the table it needs.
When to plant
Broccoli keeps to the cool bookends of the year, a tempo the kitchen gardener learns to anticipate. Start seeds indoors in late winter for a spring planting or in July for a fall one, set the hardened-off transplants out while the air stays cool, and bring in the main head before summer heat or a hard frost closes the window.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6-8 weeks before the last spring frost (early to mid-April in cold climates); sow again in early to late July for a fall crop
- Plant: Set hardened-off transplants out around 2-3 weeks before the last spring frost; transplant the fall crop in mid to late summer
- Harvest: Harvest the main head in late spring to early summer (spring crop) or in autumn (fall crop) when it is 3-6 inches across and buds are still tightly closed; side shoots follow for several weeks
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Broccoli's troubles tend to gather at the head or the roots, and most trace back to temperature or timing. Read the early signs and you can usually rescue this crop or quietly improve the next planting. Find the symptom below that matches your row, then step in while it still makes a difference.
A once-tight head relaxes into sprays of yellow bloom
This is bolting, the work of heat once temperatures settle above about 80°F (27°C) as the head matures. A late harvest or a thirsty spell hurries it on. Cut the head the moment the buds begin to loosen, since quality fades quickly, and plan the next crops so the heads come in during cool weather.
Fix:
- Harvest immediately at the first sign of loosening buds; quality declines fast
- Cut bolted heads off so side shoots may still form in cooler weather
Plants sag through midday and pale despite generous watering
The story usually lies at the roots. Lift a wilting plant and read it: white legless maggots and tunneled roots point to cabbage root maggot, while swollen, knotted galls point to clubroot, a soil disease partial to acidic ground. Discard infected plants rather than composting them, shelter the rest with row covers or stem collars, and rest that bed from brassicas for three to four years.
Fix:
- Remove and destroy infested or infected plants (do not compost clubroot material)
- For root maggot, protect remaining plants with row covers or collars at the stem base
- For clubroot, lime soil toward pH 7 and rotate out of brassicas for several years
A small head appears well before the plant fills out
What you are looking at is buttoning, usually the aftermath of a cold spell that met young transplants near or below 40°F (4°C). Oversized or rootbound seedlings and a rough start carry a plant the same way. Take the little head to the kitchen, since it rarely sizes up, then replant with stocky transplants set to the season's rhythm.
Fix:
- Harvest and eat the small head; the plant rarely sizes up afterward
- Keep remaining plants evenly watered and side-dress with nitrogen
- Replant with fresh, properly sized transplants timed to the season
Hole-riddled foliage where green caterpillars have been feeding
The likely guest is the imported cabbageworm, the velvety green larva of the white cabbage butterfly, often with cabbage loopers and diamondback moth larvae alongside. Look on the leaf undersides and into the head for the caterpillars and their frass. Handpick what you find, treat with Bt or spinosad while the larvae are small, and lay row cover over the planting from the day you transplant.
Fix:
- Handpick caterpillars
- Apply Bacillus thuringiensis (Bt) or spinosad per label while larvae are small
- Soak harvested heads in cold salted water to drive out hidden caterpillars
Toxicity
Broccoli sits comfortably on the safe side of the garden, a food crop through and through. No part of it is toxic to pets, livestock, or people, and the whole head and stem are welcome at the table. The single note of caution is portion, since a generous bowl of raw brassica can leave an animal a little gassy.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
Broccoli poses no danger to cats. Most pay it no mind, and a curious nibble brings nothing worse than a little gas.
Dogs None
It is safe for dogs in small amounts, and many take to a crunchy piece. Keep the helping modest, since a large bowl of raw florets can leave a dog gassy or briefly off its food.
Horses Safe
Nothing here troubles a horse. Brassicas can run a touch gassy, so offer broccoli as an occasional snack rather than a regular feed.
Rabbits Safe
Rabbits can take broccoli leaves and small pieces of head safely. Introduce it slowly, since too much too soon may bring on gas.
Livestock Safe
Cattle, goats, and sheep accept broccoli and its trimmings without harm. Only heavy, repeated feeding of raw brassicas is worth avoiding.
Birds Safe
Chickens and other backyard birds peck at broccoli without trouble, leaves and florets alike. It makes a welcome green that costs nothing once the heads are cut.
People Safe
Broccoli is a staple of the table, fine raw or cooked, with no part of the head or stem off limits. Wash garden-cut heads well to clear any hidden caterpillars and soil.
No special handling precautions; wash garden-harvested heads to remove insects and soil before eating.
Varieties
Dozens of broccoli varieties exist, sorted largely into the quick spring types and those that hold against the heat. These are the names that turn up most often on the seed rack.
De Cicco
De Cicco is an early Italian heirloom that offers a modest central head and then a long, generous procession of side shoots.
Calabrese
Calabrese is the classic open-pollinated Italian type, prized for a medium green central head and an ample run of side shoots after.
Packman
Packman is an early hybrid that heads up in about 55 days from transplant, which makes it a favorite for the spring table.
Green Magic
Green Magic is a heat-tolerant hybrid that keeps its poise once warm weather arrives, where many others would bolt.
Companions
Broccoli grows best beside plants that use space it leaves open or pull its pests away, and worst beside its own brassica cousins, which share the same diseases and crowd it for food.
Plant near
onions: Alliums make efficient use of space among widely spaced broccoli and their strong scent is traditionally credited with deterring some brassica pests
aromatic herbs (e.g., dill, chamomile): Flowering aromatic herbs attract beneficial insects, including parasitoid wasps that attack cabbageworm and other caterpillar pests
beets: Low-growing, light-feeding root crop that does not compete strongly with heavy-feeding broccoli for nitrogen or space
Keep apart
strawberries: Traditionally listed as a poor companion for cole crops; strawberries compete in the bed and are commonly recommended to be kept separate from brassicas
other heavy-feeding brassicas (cabbage, cauliflower, Brussels sprouts) in the same bed: Closely related crops share the same pests and soilborne diseases (clubroot, root maggot) and compete for nutrients; extensions recommend 3-4 year rotation away from all brassicas
How to propagate
Broccoli is raised from seed, started indoors and carried out as a transplant for either a spring or a fall crop.
SeedEasy
Sow indoors 6-8 weeks before the last spring frost, or sow indoors or direct in early to late July for a fall crop · Germinates in about 4-7 days in warm soil; reaches transplant size in 5-6 weeks (fall crop) to 6-8 weeks (spring crop)
Nearly all broccoli begins as seed, a simple ritual of the late-winter windowsill. Sow indoors 6 to 8 weeks before your last spring frost, or start a fall crop indoors or direct in July, and the seeds rise in 4 to 7 days in warm soil. Harden the seedlings off, set them a touch deeper than they grew in the cell, and space them 18 to 24 inches (45 to 60 cm) apart. Pass over any leggy or rootbound transplant, since those are the ones that button.
Myths
Harvesting the main head marks the end of the season; the spent plant should come out of the bed.
Leave the plant standing after the central head comes off and it carries on giving. Side shoots rise from the leaf axils, and you can harvest them for weeks, especially through cool fall weather, a quiet bonus for the kitchen. Pulling it early simply closes the season too soon.
Frost ruins a broccoli crop.
Broccoli is a cool-season crop that meets a light frost with composure. Fall plants keep growing and producing after the first frosts, and the cold often sweetens the heads for the table. Only young transplants want protection once it slips below 32°F (0°C).