How to grow broccoli in a raised bed

To grow broccoli in England, sow from March to May and choose the type for the season you want: calabrese goes into the bed in May or June for heads from summer into autumn, while sprouting broccoli is planted out in July or August and crops the following spring. Both need full sun, firm netting against pigeons and caterpillars, and plenty of space.

This page covers the two types, when to sow and plant, spacing, how many fit a raised bed, care, harvest, clubroot and pests. It is about growing broccoli plants in the garden, not sprouting broccoli seeds on a windowsill for salads.

Broccoli quick facts

Calabrese or sprouting broccoli?

The RHS describes calabrese as forming one large green central head, and sprouting broccoli as bearing clusters of small, usually purple, buds on long leafy stems. Gardeners' World adds that calabrese is the common supermarket type and produces smaller heads after the main one is cut, while sprouting types give smaller heads over a longer period.

The bigger difference for a raised bed is time. Calabrese is a summer crop that is in and out within about 15 weeks. Sprouting broccoli is planted in summer, stands through winter and crops in spring, so it holds its space for most of a year. Gardeners' World says purple sprouting broccoli tolerates temperatures down to -12°C.

When to sow broccoli

Both types are sown from March to May. You can sow in a seedbed or modules and transplant the young plants at about 10 cm tall, or sow direct where they will grow.

• Calabrese dislikes root disturbance and, according to the RHS, may bolt if it is moved in warm weather. The RHS advises sowing it direct in its final position from April onwards. Sowstory plans calabrese into the bed in May or June.
• Sprouting broccoli is raised in spring and planted out in July or August, according to Mr Fothergill's, to crop from February to May.

Sowing fits our lists of what to sow in March, April and May; planting sprouting broccoli out appears in July and August. These are England-wide months; in colder areas, start a little later in spring.

Planting broccoli out

If you raise plants in a seedbed or modules, move them to the bed while they are small: Mr Fothergill's transplants at about 10 cm, and the RHS at 10–15 cm, any time from mid-spring to late summer depending on the type. Calabrese is the fussier of the two. Because it can bolt if its roots are disturbed in warm weather, the RHS suggests sowing it straight into its final spot from April, or moving young plants in cooler weather.

Plant each one in the centre of its reserved square, water it in and get the netting on straight away; pigeons can strip young brassicas quickly.

Broccoli spacing in a raised bed

Sources give a range, and Sowstory uses the more generous figures:

• Calabrese: the RHS spaces plants 30 cm apart, or 45 cm for large varieties, in rows 45 cm apart. Mr Fothergill's gives 45 cm each way. Sowstory reserves a 45 × 45 cm square per plant.
• Sprouting broccoli: the RHS gives 60–80 cm, and Mr Fothergill's 60 cm each way. Sowstory reserves 60 × 60 cm, the lower end of the RHS range.

In a 1.2 × 2.4 m bed (about 4 × 8 ft), a simple grid would fit about ten calabrese or eight sprouting broccoli if the whole bed were given over to one crop. Sowstory caps them at four calabrese and three sprouting broccoli per bed, which leaves room for other crops.

Sprouting broccoli can reach about 90 cm tall and as wide, so Sowstory places it on the north edge of the bed, where it will not shade shorter crops. Calabrese is medium height. See our raised bed layout guide for arranging crops by height and the vegetable spacing chart for every crop's figures.

Timing matters as much as space. Calabrese planted in May is out by late summer, so the space can take a second crop. Sprouting broccoli planted in July holds its square until the following spring, which suits the gap left by an early crop such as a spring sowing of peas.

If you would rather see how a long-standing crop like sprouting broccoli fits around the rest of the year, Sowstory lays out your bed to scale, keeps tall crops on the north edge and gives a month-by-month plan for England. It is coming soon to the App Store, and your first bed plan is free.

Caring for broccoli

• Netting. The RHS advises keeping broccoli covered with insect-proof mesh or fleece at all times against pigeons and insects.
• Support. The RHS suggests earthing up around the stems and putting a cane beside tall or exposed plants. For sprouting broccoli, do this before the autumn gales.
• Shelter and drainage. Both types do best on a sheltered site. Sprouting broccoli should not sit in waterlogged soil over winter.
• Soil. The RHS suggests a soil pH of 6 to 7.

Harvesting broccoli

• Calabrese: cut the main central head. Gardeners' World says smaller side heads follow. The RHS gives July to October for harvest and Mr Fothergill's September to November; the two sources simply differ. Mr Fothergill's says heads can reach up to 20 cm across.
• Sprouting broccoli: pick the spears from February to May the following year.

Clubroot

Clubroot is a serious soil disease of the cabbage family, caused by a slime-mould relative rather than a true fungus. The RHS says affected plants have swollen, distorted roots, are stunted and wilt, and the resting spores survive in soil for up to 20 years. It is worst from midsummer to late autumn in warm, moist soil.

The RHS suggests:

• raising plants in pots of at least 9 cm before planting out;
• improving drainage, for example with raised beds;
• buying plants only from clubroot-free sources, and not moving soil from infected ground;
• liming acid soil, which reduces but does not eliminate the disease;
• choosing resistant calabrese such as 'Komodo F1' or 'Monclano F1'.

Pigeons and caterpillars

The RHS says netting, or a fruit cage, is the only reliable protection against pigeons, which can strip brassica leaves down to the veins. Keep the netting taut and check it for holes. Cabbage white caterpillars are most likely in June to July and August to September. A mesh of 4–7 mm keeps the butterflies off, provided the leaves do not touch the mesh; flea beetles need a finer mesh of 0.8 mm or less.

What Sowstory plans for broccoli, and what it does not

• Two profiles. Summer and autumn calabrese, and overwintered purple or white sprouting broccoli. It treats both as plants raised outside the bed and planted in, or calabrese sown direct.
• Limits per bed. Up to four calabrese or three sprouting broccoli in one bed.
• England-wide months. Its windows are not adjusted for your postcode or local climate.
• Planning spacing. The 45 cm and 60 cm squares are planning allowances; large varieties may need more, so check the packet.

Broccoli and crop rotation

The RHS puts broccoli with the brassicas: cabbages, cauliflowers, kale, Brussels sprouts, kohl rabi, radishes, swedes and turnips. In its rotation, brassicas follow legumes, onions or roots, so a bed that grew peas last year is a natural home. With clubroot spores lasting up to 20 years, rotation reduces the risk but cannot clear an infected bed. Sowstory plans one season at a time and does not plan rotation across years. For companion-planting claims about brassicas, see our companion planting guide.

Sources

• RHS: How to grow broccoli
• RHS: How to grow calabrese
• Gardeners' World: How to grow broccoli
• Gardeners' World: How to grow purple sprouting broccoli
• Mr Fothergill's: Broccoli Calabrese Green Calabrese
• Mr Fothergill's: Broccoli Early Purple Sprouting
• RHS: Club root
• RHS: Pigeons
• RHS: Cabbage caterpillars
• RHS: Insect-proof mesh
• RHS: Crop rotation
• Sowstory knowledge base, release v1.4