How to grow broccoli

Broccoli is easy to grow, providing you with a delicious, nutritious crop of blue-green heads, which can be harvested from summer to autumn, depending on when you sowed the seed. There are several types of broccoli to grow, including calabrese, which is the most common type of broccoli sold in supermarkets. This is named after the Italian region of Calabria and has one large head, but smaller heads develop after the central head is cut.

Sprouting broccolis, including purple sprouting broccoli, produce smaller heads but can be harvested over a longer period.

Broccoli is a popular vegetable, thanks to its vitamin content and its versatility in the kitchen. It can be used in anything from salads to curries, as well as steamed and served as a side dish.

Where to grow broccoli

Grow broccoli in fertile soil in a sunny spot. You can grow broccoli in open soil or in raised beds at least 75cm deep, or in large containers.

Broccoli benefits from crop rotation, and does best in soil where beans or peas were growing previously. This is because peas and beans are legumes, which fix nitrogen in the soil, aiding leaf growth in plants that are in the brassica family.

Broccoli needs to grow in alkaline soil, so use a soil pH test kit to measure its alkalinity before you start. Acid soil can be made alkaline by adding lime – this is easier to do in raised beds or containers.

How to sow broccoli seed

Broccoli is easy to raise yourself from seed. If you have a growing space such as a greenhouse, polytunnel or glass porch, start early by sowing broccoli seeds in modules or small pots, from late winter to early spring. Sow sprouting broccoli a little later, from early spring to early summer. Sow in small pots or modular trays of peat-free compost, placing two seeds per pot or module. Thin to the stronger one when the seedlings have appeared and grow on until the plants have four or five leaves. At this stage your broccoli plants are ready to plant out.

To sow broccoli outdoors from early spring, sow in rows in a seedbed and thin the seedlings to 8-10cm apart to grow on for transplanting. Unless you have lots of room, don’t sow broccoli in its final position. Starting broccoli in pots or a seedbed and then transplanting to its final position is best, because broccoli takes up a lot of space in the garden.

How to plant out broccoli

Prepare the soil for broccoli several months in advance of sowing or planting, so the ground has time to settle. Unless your soil is already rich and fertile, add plenty of well-rotted compost or manure. Broccoli needs to be planted firmly in the soil, so if it's loose at planting time, tread it over to firm and consolidate the ground.

Plant broccoli around 3cm deeper than the plants were growing in pots or the seedbed, so the stem is well supported. Space plants 30cm apart with 45cm between rows. Sprouting broccoli needs a bit more room, at 45cm spacings, so there's plenty of space for side shoots to develop. Firm the soil well around the roots – this is important as broccoli doesn’t thrive in loose soil – and water well.

Watch Monty Don demonstrate how to plant out broccoli into soil where broad beans previously grew:

How to care for broccoli

Regular watering during dry spells is important as broccoli shouldn’t be allowed to go short of water. Keep the soil around the crop clear of weeds, which would compete for water and nutrients. Remove any yellowing leaves which could become the source of diseases.

As broccoli develops into large plants, securely stake or support the crop to avoid the plants rocking in the wind and loosening the roots.

Covering the crop with fine insect mesh is good practise to ensure protection against pests and birds.

Pests and diseases

Broccoli is prone to several problems that commonly affect plants in the brassica family.

The caterpillars of large and small white butterflies frequently cause damage, making holes in the leaves and eating into the heart of the plant. You can pick caterpillars off by hand or use insect-proof netting. However, you may find that wasps take most of the caterpillars from the plants to feed their young, and the plants recover after the caterpillars have completed their lifecycle. You can also grow nasturtiums nearby to attract caterpillars from your brassicas onto the nasturtium leaves.

Club root is a soil-borne disease occurring mostly in the warmer months. It infects the roots, causing them to become swollen, affecting the growth of the broccoli plants above ground. Improving drainage can help, as can adding lime to make the soil more alkaline. If your plants are affected, don't grow brassica plants.

Harvesting broccoli plants

Depending on the type of broccoli you're growing, you can start cutting spears about 10-12 weeks after sowing, when they’re well-formed but before the buds open into flowers. Cut the main, central head, first, which will trigger the development of side shoots. Then continue to cut side shoots regularly over the next four to six weeks. Use a sharp knife to cut where the base of the spear meets the main stem.

Preparation and uses

Looking for inspiration on how to use your crop? Our friends at olive have curated a delicious collection of broccoli recipes, including their easy baked gnocchi with broccoli, blue cheese and walnuts.

Storing broccoli

Ideally, use broccoli as soon as possible after harvest, for maximum taste and nutrition. However, broccoli heads keep for at least a week in the fridge and sprouting broccoli keeps for several days. Storing in the salad drawer is best.

To freeze broccoli, first blanch (part cook) otherwise it will be soggy when defrosted. Prepare your broccoli by washing the heads and chopping or breaking up into small florets. Place in a large pan of boiling water for 3 minutes, then drain and transfer to iced water. Drain, then spread out on a baking sheet to freeze, transferring to freezer bags or plastic containers after a few hours.

Broccoli varieties to grow

Broccoli 'Green Magic' RHS AGM – an early maturing variety with a good flavour and rust resistance

• Buy broccoli 'Green Magic' from Thompson & Morgan

'Brokali Apollo' – a cross between broccoli and Chinese kale, with tasty, tender stems similar to those of sprouting broccoli

• Buy brokali 'Apollo' from Sarah Raven

White sprouting broccoli – white-sprouting broccoli has a slightly milder flavour than purple or green

• Buy white sprouting broccoli from Thompson & Morgan

‘Early Purple Sprouting’ – purple-sprouting broccoli is tasty and nutritious and the leaves are also edible

• Buy ‘Early Purple Sprouting’ broccoli from Chiltern Seeds

Frequently asked questions

How long does it take to grow broccoli?

Once young broccoli plants are in the ground, it takes from around 10-12 weeks to start producing a crop. This does depend on the variety and time of year – purple sprouting broccoli takes longer because it stands in the ground over winter and crops in spring.

Can you grow broccoli from broccoli?

You can grow a new crop of leaves, and perhaps small broccoli heads, by putting the waste stems from broccoli flower heads in jars of water on the windowsill. Cut off a small section from the base of the stem to ensure good water uptake. While this won’t produce a big crop, it’s a fun thing to do with either home-grown or shop-bought broccoli. This only works with the chunky stems of calabrese broccoli, not the slender stems of sprouting types.