RHS Growing Guides
How to grow broccoli
Our detailed growing guide will help you with each step in successfully growing Broccoli.
Getting Started
Broccoli, or sprouting broccoli, is a delicious, nutritious and easy-to-grow member of the cabbage family. It forms multiple small clusters of purple or white buds for harvesting from summer onwards. Winter varieties provide especially valuable harvests right through to spring.
Broccoli plants produce small clusters of buds for several months if harvested regularly
Broccoli (Brassica oleracea (Italica Group)) produces repeated harvests for up to two months – it’s traditionally a winter/early spring crop, but newer varieties offer harvests from summer onwards, depending on the sowing time. The more compact, faster-growing summer varieties are best for smaller plots, while the more traditional winter and spring cropping varieties form large plants, up to 90cm (3ft) tall and wide, and can take eight months or more to mature. They provide a valuable crop at an otherwise lean time of year and you don’t need many plants to enjoy ample pickings. Sprouting broccoli can also be expensive to buy, so is well worth growing.
Broccoli is a brassica, so should be grown with its other cabbage relatives in crop rotations. It’s susceptible to the usual issues that affect brassicas – see Problems below.
Although broccoli is usually quite a slow crop, it can also be grown as microgreens on a sunny windowsill. Seeds will produce sprouts in about two weeks. The tasty, nutritious seedlings can be added to salads and sandwiches.
Month by Month
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Choosing
You can grow creamy-white broccoli, as well as the more familiar purple varieties
Most varieties produce purple flower buds, but a few are creamy-white; purple varieties tend to be hardier and more productive, but both are attractive, delicious and well worth growing. Broccoli is usually most successful in cooler summers, as hot weather can cause flower buds to develop prematurely (bolt), resulting in a smaller crop. Bolt-resistant varieties are a good choice for warmer regions.
For the most reliable broccoli varieties, look for those with an RHS Award of Garden Merit (AGM), which shows they performed exceptionally well in trials – see our list of AGM fruit and veg (135kB pdf) and our Recommended Varieties below. You can see many crops, including broccoli and other brassicas, in the veg plots at the RHS gardens, so do visit to explore how they’re grown, compare the varieties and pick up useful tips and inspiration.
What and where to buy
Broccoli seeds are widely available from garden centres and online gardening retailers. Young plants are available in spring and early summer from similar sources, but the choice of varieties will be more limited. You can also buy seeds specifically for growing as microgreens.
Recommended Varieties
Preparing the Ground
Broccoli grows best in fertile, well-drained soil, in sun or very light shade. It forms quite tall plants, so choose a sheltered spot where they won’t be buffeted by strong winds. Avoid soil that gets waterlogged, especially during winter if growing an overwintering variety. If your soil is very acidic, apply lime the winter before sowing, to raise the pH and deter club root disease. Broccoli prefers a soil pH of 6 to 7. You can carry out a simple pH test to find out the pH level of your soil.
Before sowing or planting, weed thoroughly and dig in two bucketfuls of well-rotted manure or garden compost per square metre/yard. Ideally do this several months beforehand, to allow the ground to settle. If done just before planting, firm the soil well by treading it down using shuffling steps, then rake smooth.
Alternatively, if you're practicing no-dig, mulch the soil with organic matter ahead of sowing or planting directly into the mulch.
Sowing
Broccoli seeds can be sown from February to July – indoors from February or outdoors from April. Sow small batches several weeks apart to provide regular pickings over a long season. Broccoli seeds can also be sown throughout the year and placed on a sunny windowsill to grow into microgreens.
Sowing indoors
From February, you can start sowing broccoli in a greenhouse or on a sunny windowsill. You can continue sowing batches indoors through to June, or start sowing outdoors (see below) from April. Sowing indoors is useful if you want an early harvest, as it gives plants a head start. It’s also beneficial if you have club root disease in your soil, as you can ensure the plants have a well-developed root system before being moved into the ground, so they should be less severely affected.
It’s best to use a modular seedtray, to minimise root disturbance when transplanting later. Fill it with peat-free seed compost, water to dampen thoroughly, then sow two seeds per module, 2cm (¾in) deep.
Broccoli seeds should germinate within two weeks without additional heat. Thin out the seedlings, removing the smaller or weaker one, to leave one per module. When the young plants are 10–15cm (4–6in) tall with a good root system, move them outdoors – see Planting, below.
Sowing outdoors
Sow broccoli seeds outdoors from April to July – either in a seedbed (for transplanting later – see Planting below) or straight into their final position if you have space. Prepare the ground as explained above, then make a shallow drill about 2cm (¾in) deep and water along the base.
If sowing in a seedbed, sow seeds about 7.5cm (3in) apart – or thin out to this distance once seedlings appear. If sowing in their final position, sow three seeds every 60–80cm (24–31in), depending on the variety, then thin out each cluster to one strong seedling as soon as they are large enough to handle. Protect young plants from slugs and snails, especially in damp weather. For more sowing tips, see our guides below.
Sowing microgreens
Broccoli is very quick and easy to grow as microgreens on a sunny windowsill. Sow the seeds at any time of year into a small seedtray of damp peat-free seed compost. Water regularly, and in a couple of weeks or less, the tasty fresh green sprouts will be ready to add to salads and other dishes.
Planting
Once young plants have a good root system and several leaves, transplant to their final location
Protect young plants from slugs and snails and cover with insect-proof mesh or biodegradable fleece to reduce insect damage.
Plant Care
It’s best to cover broccoli with fine-mesh netting at all times, to protect the crop from pigeons and various insects. Weed between young plants regularly, water during dry spells and support taller plants with sturdy canes.
Watering
Water broccoli seedlings and young plants during dry spells to ensure they establish well. After that, you should only need to water during prolonged dry weather. See our water-saving tips below.
Mulching
Mulch with a thick layer of organic matter, such as garden compost, to help retain moisture and deter weed germination.
Feeding
If your soil is poor, you can apply an organic high-nitrogen fertiliser when broccoli plants are about 20cm (8in) tall.
Weeding
Keep the soil free of weeds, so young broccoli plants don’t get overwhelmed by vigorous weeds or outcompeted for water or sunlight.
Supporting plants
Broccoli plants generally grow to 60–90cm (2–3ft) tall and usually need support, especially in exposed locations. If these top-heavy plants are buffeted around by the wind, this can loosen the roots and hinder growth. So, before any autumn gales arrive, pile soil up around the base of the stem to increase stability and/or insert a sturdy cane and tie in the main stem, to keep it upright.
Protecting the crop
Harvesting
Harvest the whole shoot, about 10cm (4in) long, as the stem and leaves are edible too
Broccoli is ready to harvest when the small heads, or spears, are well formed but still tightly in bud. Remove the whole shoot, cutting at the base, with about 10cm (4in) of stem and any small leaves, which can all be eaten. Take the central spear first, then more will form on the side-shoots, which can be harvested over the following weeks. Check plants regularly, so you catch them before the clusters of buds start to open. The more shoots you harvest, the more the plants will produce.
Broccoli can be cooked in various ways – lightly steamed, sautéed or stir-fried – until tender, succulent and delicious. It can be eaten as a side dish or given pride of place in a wide range of delicious meals. Purple varieties generally turn green when cooked. Broccoli is best used as fresh as possible, but can be kept in the fridge for a few days and freezes well.
Problems
Broccoli usually grows and crops well, although it may bolt in hot weather, which means it starts to flower prematurely, before plants are at full size, leading to a smaller crop. Harvest these early clusters of buds as soon as you see them forming, before they rapidly open into flowers. Broccoli is also susceptible to several insects that affect the cabbage family, so is best grown under fine-mesh netting. If you have club root disease in your soil, start broccoli off indoors so it has a well-developed root system before you transplant it into the ground – it should then be less severely affected. For more on these and other issues, see Common problems, below.
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