RHS Growing Guides
How to grow calabrese
Our detailed growing guide will help you with each step in successfully growing Calabrese.
Getting Started
A popular and tasty crop, calabrese produces large domed green heads up to 15cm (6in) across, for harvesting in summer and autumn. Growing calabrese yourself means you can enjoy it freshly picked, when its mild flavour and many beneficial
Calabrese and broccoli are two different crops, but they are often muddled up, with both plants widely referred to as broccoli. But in gardening terms there’s a clear distinction:
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Calabrese plants produce a large central green head of tightly packed buds, ready to harvest from mid-summer to mid-autumn (this is confusingly called broccoli in supermarkets and recipes)
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Broccoli plants (also known as sprouting broccoli) produce much smaller clusters of purple or white buds on the tips of leafy stems. For more on this crop, see our guide to growing broccoli
Calabrese is mainly sown in spring, either indoors or outside, and is ready to harvest in three or four months, from July to October, depending on the variety and sowing time. It grows up to 60cm (2ft) tall and wide, forming a large central green head, which is a cluster of tightly packed flower buds. After cutting the main head, further smaller heads form on side-shoots, extending the harvest for up to eight weeks.
Calabrese is a member of the cabbage (brassica) family, so should be grown alongside its relatives in crop rotations and protected from the main brassica pests and diseases – see Problem solving, below.
The main head is ready to harvest when large and firm but still tightly in bud. Delicious and versatile, calabrese is best lightly steamed or stir-fried and can be used in all kinds of dishes. It’s particularly popular in Italian cuisine and is named after Calabria in southern Italy. Often hailed as a superfood, calabrese is rich in nutrients, including anti-cancer compounds.
Month by Month
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Choosing
You’ll find a wide selection of calabrese varieties available as seed, offering variations in sowing/harvesting times, plant size, and resistance to bolting, clubroot and other diseases. Most form a large domed green head, followed by smaller heads for harvesting over a long period. Choose compact varieties if space is tight, as they can be grown closer together.
For the most reliable calabrese 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 for recommended varieties of calabrese and many other crops.
To help you choose calabrese varieties, why not visit the veg plots in the RHS gardens? You’ll see many crops, including calabrese and other brassicas, and can explore how they’re grown, compare the varieties and pick up useful tips and inspiration.
What and where to buy
Calabrese seeds are widely available from garden centres and online gardening retailers (although, confusingly, they are sometimes sold as broccoli). Young calabrese plants may also be available in spring from similar sources, but the choice of varieties may be very limited.
Recommended Varieties
Very reliable variety, producing a good crop of large tight heads, followed by side-shoots. Can be sown over a long period.
An early maturing variety with dense heads followed by side-shoots. Ready to harvest 60–70 days after sowing. Good...
Compact plants, so ideal where space is limited. Particularly good for autumn cropping.
Preparing the Ground
Calabrese prefers firm, fertile, well-drained soil in a sheltered sunny or lightly shaded spot. If possible, choose and prepare your growing site in advance:
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The previous autumn, dig in two bucketfuls of well-rotted manure or garden compost per square metre/yard, to allow the ground time to settle over winter. If done closer to planting time, firm the soil really well by treading it down, shuffling back and forth over it, then rake it smooth.
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If your soil is very acidic, apply lime the previous winter to raise the pH and deter clubroot disease. Calabrese prefers soil with a pH of at least 6.8.
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Rake in a high potassium general fertiliser, such as Vitax Q4 – use one and a half handfuls per square metre/yard, or three handfuls if no manure or garden compost has been added.
Sowing
Calabrese seeds are generally sown between February and June – indoors from late winter into mid-spring, then outdoors from mid-spring to early summer.
If you sow several small batches a few weeks apart, you can spread out your harvests and avoid gluts.
Calabrese should be grown in the same bed as its other cabbage relatives in crop rotations, to avoid any build-up of pests and diseases in the soil.
Sowing indoors
Growing calabrese from seed
Calabrese doesn’t transplant well in warm weather, making it prone to bolting (premature flowering), so after April it is best sown in its final position outdoors (see below).
You can also sow in autumn and overwinter the young plants in a greenhouse, to plant out the following spring for an early crop.
Sow calabrese in modular trays, to minimise root disturbance when transplanting later. Fill the tray with seed compost, water well, then sow two seeds into each module, 2cm (¾in) deep.
Seedlings should appear within a couple of weeks. As soon as they are large enough, thin them out to one seedling per module.
Apply a general-purpose liquid fertiliser once a week.
When the young calabrese plants are 10–15cm (4–6in) tall and have a well-formed rootball, move them outdoors – see Transplanting, below.
Sowing outdoors
From April to June, you can sow calabrese seeds outdoors, either on a temporary basis in a seedbed (for transplanting later – see below) or straight into their final site if you have space. Sowings after mid-spring are best made in their final position, as calabrese doesn’t transplant well in warm weather.
Choose and prepare your sowing site as explained above, then make a shallow drill about 2cm (¾in) deep:
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If using seedbed, sow the seeds thinly along the drill, ideally 7.5cm (3in) apart, or thin out the seedlings to that spacing if sown more thickly.
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If sowing in their final position, sow three seeds every 30cm (1ft) along the drill, then thin out each cluster of seedlings to leave just one at each point. Larger varieties may need to be spaced up to 45cm (18in) apart – check the seed packet.
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Cover the bed with fleece to exclude cabbage root fly
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Weed and water regularly
Sowing calabrese outdoors with protection
Transplanting
Choose and prepare your site as detailed above.
Plant young calabrese deeper than they were previously growing, with the lowest leaves level with the surface, so they root in securely. Firm them in really well. Space plants 30cm (1ft) apart, with 45cm (18in) between neighbouring rows, then water generously. Closer spacing with result in smaller heads. Larger varieties may need wider spacing, up to 45cm (18in) apart.
Plant Care
Calabrese is a fast-growing brassica and needs little maintenance apart from weeding regularly and watering during dry spells. Keep plants fully covered with fine-mesh netting to protect them from cabbage butterflies and pigeons.
Watering
Water calabrese seedlings and young plants regularly until well established.
Once they have a good root system, they should only need watering during dry spells, to avoid any check in their growth, which could cause them to bolt (flower prematurely).
Mulching
Apply a thick mulch of garden compost to help hold moisture in the ground and deter weeds.
Feeding
When plants are about 20cm (8in) tall, apply a high nitrogen fertiliser, such as sulphate of ammonia, at 35g (1oz) per square metre/yard.
Supporting plants
Once the main head starts to form, calabrese plants can become top-heavy, so pile soil up around the base of the stem to improve stability. Buffeting by the wind can loosen the roots and hinder growth.
Larger varieties and those in exposed sites should be given additional support – insert a sturdy cane and tie in the main stem to hold it secure.
Protecting for pests
Calabrese is susceptible to all the main brassica pests, so cover the crop with insect-proof mesh, supported on canes and pinned to the ground. This will deter cabbage caterpillars, cabbage root fly and pigeons - see Problem solving, below.
Harvesting
Harvesting calabrese
After you harvest the main head, further small heads will develop on side-shoots, which can be picked regularly over the following weeks. The young, tender leaves can also be eaten. Check plants every few days to ensure you harvest the new heads before the flowers open. Regular harvesting encourages plants to produce further small heads, extending the cropping season for up to a couple of months.
In the kitchen, calabrese can be lightly steamed, sautéed or stir-fried until tender and delicious. Take care not to overcook it, as it will turn mushy. Calabrese should be used straight after harvesting if possible, when packed with flavour and nutrients, but can be kept in the fridge for a few days or frozen for later use.
Problems
Calabrese usually grows and crops well, but it may bolt (flower prematurely) during hot weather. Choose a bolt-resistant variety in warmer regions.
It is susceptible to several pests and diseases that affect the cabbage family, including clubroot and cabbage root fly. Covering the crop with fine-mesh netting, supported on a framework, will keep several pests at bay, including cabbage caterpillars and pigeons. Cabbage whitefly and aphids can also cause problems. Wide spacing between plants helps to deter pests and fungal diseases.
If you have clubroot disease in your soil, sow calabrese indoors so it can develop a good root system before being moved into the ground. It should then be less severely affected.
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