Overview
What broccoli needs, when it crops, and which type suits your garden.
The broccoli you eat is a cluster of flower buds, cut before a single yellow flower opens. That is why timing matters so much: it has to head up in cool weather, as cold stress and summer heat both spoil the crop. Sow for the cool ends of the year, and one small bed can give heads and spears for months.
Quick facts
- Botanical name
- Brassica oleracea (Italica Group)
- Soil pH
- 6.0 – 7.0
- Feeding
- Heavy feeder
- Temperature
- 16 – 21 °C
- Hardiness
- Any zone, as an annual
- Time to harvest
- 55 – 75 days
- Height
- Up to 90 cm (35 in)
- Propagation
- Seed
Optimal growth
Growing details
- Spacing
- 45 cm (18 in)
- Sowing depth
- 13 mm (½ in)
- Frost sensitivity
- Frost hardy
Growing calendar
- Start indoors: February, March, April, May, June
- Transplant: March, April, May, June, July, August
- Harvest: January, February, March, June, July, August, September, October, November, December
In modules, four to seven weeks before planting out; batches through spring for a long harvest. Spring crops a few weeks before the last frost; autumn crops from midsummer. With regular sowings, June to the following March in the UK (RHS).
Is this plant right for you?
- Cool-season crop
- Frost hardy
- Raised-bed friendly
- Needs pest netting
- Heavy feeder
- Spring and autumn crops
- Winter varieties
Good to know
It is a hungry plant, so feed it regularly right through the growing season. It stands frost, so it can go out earlier than tender crops.
Before You Grow
Pick calabrese for one big head or sprouting broccoli for months of spears, and a sunny spot with firm, fertile soil.
In the UK ‘broccoli’ means sprouting broccoli; the big supermarket head is calabrese.
What you need
Seed or young plants
Seed gives more choice. Bought plants should be young and stocky with four to six leaves. See choose your broccoli.
Module trays and seed compost
For raising transplants. See how to raise plants.
A sunny bed with firm, fertile soil
Not used for brassicas in the last three or four years. See soil.
Fine insect mesh or fleece
On hoops or canes, from planting day. See pests.
Canes for tall plants
Winter sprouting types grow up to 90 cm (3 ft). See support and protection.
A sharp knife
For cutting heads and spears.
Choose your broccoli
‘Broccoli’ covers several crops, and the name means different things in different countries.
Calabrese, or heading broccoli, makes one large central head, 7.5 to 20 cm (3 to 8 in) across, then smaller side shoots after it is cut. This is what US sources mean by broccoli, and what supermarkets sell. Most varieties crop 55 to 75 days after planting out.
Sprouting broccoli, what the RHS calls broccoli, makes many small spears, usually purple, sometimes white, over up to two months. Traditional varieties are big, hardy plants sown in spring that crop in late winter and spring, when little else does; newer ones crop from summer.
Romanesco has striking lime-green, spiralled heads. Broccoli raab isn’t a true broccoli: it is a turnip grown for its flower shoots.
Heat. Broccoli does best in cool summers. Where summers are warm, choose bolt-resistant or heat-tolerant varieties such as ‘Green Magic’.
Purple or white. Purple sprouting varieties tend to be hardier and more productive; white ones are a little milder.
Broccoli types compared
-
Calabrese (heading)
- What you harvest
- One big head, then side shoots
- Time to crop
- 55 to 75 days from planting out
- Notes
- ‘Green Magic’, ‘Packman’, ‘Premium Crop’
-
Summer sprouting
- What you harvest
- Many small spears
- Time to crop
- A few months from sowing
- Notes
- Compact, faster; for smaller plots
-
Winter sprouting
- What you harvest
- Many purple or white spears
- Time to crop
- Eight months or more
- Notes
- Large, very hardy; crops late winter to spring
-
Romanesco
- What you harvest
- One spiralled head
- Time to crop
- See the packet
- Notes
- Striking lime-green spirals
-
Broccoli raab
- What you harvest
- Leafy flower shoots
- Time to crop
- See the packet
- Notes
- A turnip, not a true broccoli; sown direct
For a crop within a couple of months in spring or autumn, calabrese; for fresh greens in late winter and early spring, when little else is ready, winter sprouting broccoli.
Where broccoli grows best
Broccoli is a cool-season crop. It grows best at 16 to 21 °C (60 to 70 °F) and gives the highest yields when it stays below about 24 °C (75 °F).
Heat is the main enemy of heading types. Iowa State finds days of 30 °C (86 °F) or more with nights of 25 °C (77 °F) or more can stop broccoli forming heads, and hot weather gives loose, bitter heads.
Cold. Plants shrug off frost: Utah State finds them undamaged down to about -2 °C (28 °F), and winter sprouting varieties stand the whole winter. But young plants exposed to long spells below 7 to 10 °C (45 to 50 °F) may ‘button’ or bolt.
Shelter. Tall plants rock in the wind, which loosens their roots. Choose a sheltered spot, and avoid ground that waterlogs in winter for overwintering types.
Sun. Full sun: at least six hours of direct sun a day; the University of Maryland prefers eight to ten. The RHS also grows broccoli in very light shade.
Spacing matters for light and air. Generous spacing lets light and air between plants, which cuts disease and encourages more side shoots.
- Best growth
- 16 to 21 °C (60 to 70 °F)
- Stops heading
- Days 30 °C (86 °F), nights 25 °C (77 °F)
- Frost
- Stands light frosts; winter types all winter
Soil
Broccoli wants fertile, moisture-retentive but well-drained soil, rich in organic matter, and firm.
Preparation. Weed, then dig in about two bucketfuls of compost or well-rotted manure per square metre, ideally several months ahead so the ground settles. If you prepare it just before planting, tread the soil firm.
pH. The RHS and Iowa State give pH 6 to 7. Gardeners’ World says broccoli needs alkaline soil. All agree: lime acid soil the winter before, which also deters clubroot.
Rotation. Don’t grow broccoli where brassicas grew in the last three or four years (Iowa State). Gardeners’ World likes to follow peas or beans, which leave nitrogen behind.
Planting
Start plants in modules, plant them deep and firm, and time crops for spring and autumn.
Plant deep and firm: loose plants rock in the wind and root poorly (RHS).
When to sow and plant broccoli
Time broccoli so its heads form in cool weather: a spring crop that matures before summer heat, and an autumn crop that matures after it. UMD finds autumn crops often yield more.
Spring crop. Sow in modules four to seven weeks before planting out, and plant out two to four weeks before your last frost (UMD, Utah State). In the UK, the RHS sows indoors from February.
Autumn crop. Sow in midsummer and plant out from late June to early August. Illinois counts back from the first autumn frost: the days to harvest on the packet plus about ten.
Winter sprouting. Sow in spring or early summer; plants crop from late winter into spring.
Little and often. Small batches a few weeks apart, from February to July in the UK, give a long harvest.
- Spring crop: plant out 2 to 4 weeks before the last frost.
- Autumn crop: sow in midsummer.
- Winter sprouting: sow in spring, crops the following spring.
How to raise broccoli plants
Modules give sturdy plants that move without a check in growth.
-
Sow two seeds per module
In peat-free seed compost, about 1 to 2 cm (½ to ¾ in) deep: the RHS sows at 2 cm, US extensions at 6 to 13 mm (¼ to ½ in).
-
Keep them cool and bright
They germinate within two weeks without extra heat (RHS).
-
Thin to one
Remove the weaker seedling in each module.
-
Or sow in a seedbed
Outdoors from April, 7.5 to 10 cm (3 to 4 in) apart, to lift and transplant later.
-
Plant out young
At 10 to 15 cm (4 to 6 in), with four to six leaves and a good root system. Older, root-bound plants are the most likely to button.
How to plant broccoli
Deep, firm planting and protection from day one.
-
Harden off indoor-raised plants
Start them in a shaded, sheltered spot and give them a little more sun each day for several days.
-
Water before and after
Moist roots move with less disturbance and less check in growth.
-
Plant deeper than before
With the lowest leaves at the soil surface, or about 3 cm (1¼ in) deeper than they grew, so they root deep and firm.
-
Space them out
Calabrese 30 to 60 cm (12 to 24 in) apart in rows 60 to 90 cm (2 to 3 ft) apart. Sprouting types 45 to 80 cm (18 to 31 in) apart, as the packet says. Wider spacing gives more side shoots.
-
Firm them in
Press the soil firmly around each plant, then water well.
-
Protect them straight away
Cover with fine insect mesh or fleece on hoops, pinned down, against pigeons, butterflies and root fly. Add slug protection.
Care
Steady water, extra nitrogen as heads form, a stake in exposed spots, and mesh against pests.
Cover the crop with fine mesh from planting day: it keeps off pigeons, butterflies and root flies.
Care by growth stage
Young plants
Protect: mesh and slug control · Feed: 3 to 4 weeks after planting
Water in dry spells, weed and keep them netted. See watering.
Growing on
Water: about 2.5 cm (1 in) a week · Mulch: once soil is warm
Heads forming
Check: heads every few days
After the main head
Cut: side shoots every few days
Keep watering and feeding for side shoots. See harvesting.
Autumn and winter
Support: canes or earthing up
Stake or earth up tall winter types before gales. See support and protection.
End of season
Rotate: no brassicas for 3 to 4 years
Lift finished plants and clear the debris, which harbours disease. See diseases.
Watering broccoli
Broccoli has shallow roots and shouldn’t go short of water, especially as the heads form.
How much. About 2.5 cm (1 in) a week, rain included (Iowa State); Utah State, in a dry climate, gives 2.5 to 5 cm (1 to 2 in). Water deeply and less often, keeping the moisture even: water when the top few centimetres of soil are dry.
When it matters most. As the heads develop. Dry spells lead to buttoning and loose, poor heads that flower early.
How. At the base: soaker hoses or drip lines keep the leaves dry and cut disease.
Mulch with straw, shredded leaves or compost to hold the moisture and keep the soil cool.
Feeding broccoli
Broccoli is hungry: it has a high nutrient requirement.
Before planting, dig in compost or manure; without a soil test, Iowa State works in a general fertiliser.
After planting, use a starter feed. Three to four weeks later, side-dress with a nitrogen or general fertiliser along the row.
As heads form and again after cutting the main head, a little more nitrogen boosts the side shoots (UMD, Utah State).
In the UK, the RHS feeds only on poor soil, with an organic high-nitrogen fertiliser when plants are about 20 cm (8 in) tall.
Too much fertiliser can cause hollow stems (Utah State).
Support and protection
Tall plants need support and every plant needs protecting.
Support. Plants reach 60 to 90 cm (2 to 3 ft) and are top-heavy. If the wind rocks them, it loosens the roots and checks growth. Before autumn gales, pile soil around the base of the stem and push in a sturdy cane.
Netting. Keep the crop under fine insect mesh or fleece from planting to harvest (RHS, Gardeners’ World). It keeps off pigeons, cabbage white butterflies and cabbage root fly.
Tidy up. Remove yellowing leaves, which can harbour disease, and keep the bed weeded.
Broccoli in containers
Broccoli is a big plant, but it can be grown in a large container or a raised bed at least 75 cm (30 in) deep (Gardeners’ World).
Choose a compact calabrese or summer sprouting variety, one plant to a large container.
Compost. Rich and firm; liming is simpler to control in a container on acid ground.
Care. Containers dry out faster than beds: check daily in warm weather. See watering, feeding and netting.
Problems
Buttoning, bolting in heat, caterpillars, pigeons and clubroot are the usual brassica troubles.
Common broccoli problems
These are growing problems, not pests or diseases.
Tiny heads soon after planting
- Buttoning
- Stress
Buttoning: plants stressed by long cold spells below about 10 °C (50 °F), drought, poor soil, or planted out too old and root-bound. Use young transplants with four to six leaves and keep growth steady.
No heads in summer, or loose, bitter heads
- Heat
Hot days and warm nights stop heading and give loose heads. Plant earlier in spring, or grow an autumn crop instead.
Heads flowering early
- Bolting
- Heat
- Drought
Hot or dry weather makes broccoli bolt. Cut early clusters as soon as they form, water well while heading, and choose bolt-resistant varieties.
Brown spots on the head, hollow stem
- Boron
- Stress
Boron deficiency, linked to high-pH soil, water stress or too much fertiliser. Avoid overfeeding and keep watering even (Utah State).
Plants rocking and wilting
- Loose soil
- Wind
Loose roots. Firm the soil well at planting, and stake or earth up tall plants.
More problems with broccoli
Common pests
Cabbage caterpillars
Cabbage white butterflies, loopers and diamondback moths lay eggs whose green caterpillars eat holes in leaves and hide in heads, worse in autumn crops. Net the crop, pick them off, or use Bacillus thuringiensis (Bt). Wasps take many.
Cabbage root fly
Maggots eat the roots. Fit collars round the stems at planting, or grow under mesh.
Flea beetles
Tiny black beetles that pepper seedlings with holes. Minor damage doesn’t matter; mesh keeps them off young plants.
Mealy cabbage aphid
Grey colonies under the leaves. Knock them off with a strong water jet or use insecticidal soap.
Cabbage whitefly and slugs
Whitefly under the leaves is rarely serious. Protect young plants from slugs, especially in damp weather.
Common diseases
Clubroot
A soil-borne disease that swells and distorts the roots, stunting the plants. Improve drainage, lime acid soil, rotate, and raise plants in pots until well rooted before planting into infected ground. If it is bad, stop growing brassicas there.
White blister
White pustules on the leaves that reduce vigour (RHS). Remove badly affected leaves and space plants for airflow.
Alternaria leaf spot
Black, sooty spots in rings on leaves and heads; it can also kill seedlings (damping off). Avoid overhead watering, clear debris and rotate (Utah State).
More problems with broccoli
Harvest & Use
Cut heads while the buds are tight, and keep cutting side shoots for weeks.
Harvesting broccoli
Cut while the buds are still tight and before any show yellow: yellow flowers and swelling buds mean it is past its best.
Calabrese. The main head is ready when firm and blue-green, 7.5 to 20 cm (3 to 8 in) across depending on variety (UMD). Cut it with 13 to 15 cm (5 to 6 in) of stem (Illinois); UMD leaves 15 to 20 cm (6 to 8 in).
Side shoots. Cutting the main head makes smaller shoots grow from the leaf joints: keep cutting them every few days for weeks.
Sprouting broccoli. Cut each spear with about 10 cm (4 in) of stem and its small leaves, which are edible too. Take the central spear first. The more you pick, the more it produces, for up to two months.
Check often. Heads go from tight to flowering fast, especially in warm weather.
- Cut before any buds show yellow.
- Main head first, then side shoots for weeks.
- Check every few days.
Storing and using broccoli
Broccoli is best eaten fresh: stored too long, it develops strong, off flavours.
In the fridge. Unwashed, in a loose or perforated bag in the salad drawer. Heads keep 3 to 5 days (Illinois) to about two weeks at 0 °C (32 °F) and high humidity; sprouting broccoli a few days. Wash just before use: wet broccoli goes limp and mouldy.
Freezing. Blanch small florets in boiling water for 3 minutes, cool in iced water, drain, freeze on a tray, then bag.
Cooking. Steam, sauté or stir-fry until just tender. Purple sprouting turns green when cooked.
More to Explore
Short answers, guides that pair well with broccoli, and the sources behind this one.
Frequently asked questions
What is the difference between broccoli and calabrese?
Calabrese makes one big green head; sprouting broccoli makes many small spears. In the UK ‘broccoli’ usually means sprouting broccoli. See choose your broccoli.
Why is my broccoli so small?
Usually buttoning, from stress: cold, drought, poor soil or old transplants. See common problems.
Why is my broccoli flowering?
Heat or dryness makes it bolt. Cut heads promptly and grow for spring or autumn.
Does broccoli grow back after cutting?
Yes: side shoots follow the main head for several weeks. See harvesting.
When should I plant broccoli?
For spring, a few weeks before your last frost; for autumn, in midsummer. See when to sow and plant.
How far apart should broccoli be?
Calabrese 30 to 60 cm (12 to 24 in); sprouting types up to 80 cm (31 in). See planting.
How do I stop caterpillars on broccoli?
Grow it under fine mesh from planting day. See pests.
Can broccoli survive frost?
Yes: established plants take light frosts, and winter sprouting varieties stand the winter. See growing conditions.
How long does broccoli take to grow?
Calabrese about 55 to 75 days from planting out; winter sprouting eight months or more. See choose your broccoli.
Can you freeze broccoli?
Yes, blanched first. See storing and using broccoli.
Related guides
Sources
- How to grow broccoli (opens in a new tab) Royal Horticultural Society
- Growing broccoli in the home garden (opens in a new tab) Iowa State University Extension and Outreach
- Growing broccoli in a home garden (opens in a new tab) University of Maryland Extension
- Broccoli (opens in a new tab) University of Illinois Extension
- Broccoli in the garden (opens in a new tab) Utah State University Extension
- How to grow broccoli (opens in a new tab) BBC Gardeners’ World