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How to grow Calabrese

Calabrese Growing Guide

Make some space for calabrese - the vegetable that you buy from the supermarket labelled as broccoli. You’ll be rewarded with a quick-growing brassica that is delicious once it reaches your plate, whether you love roasted broccoli as a side dish, prefer it lightly steamed seasoned simply with salt and pepper, paired with pasta, in a broccoli and stilton soup, or simply boiled with other vegetables to up the nutrition of your meal. This so-called green sprouting broccoli grows easily in a garden in the UK, plant in your vegetable patch, or in small pots or containers indoors for a fast microgreen crop.

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Calabrese quick links

How to grow Calabrese

Calabrese is one of the most rewarding members of the brassica tribe you can grow. Chock full of cancer-fighting compounds ready for devouring within a few short months, it’s a crop that works hard to earn its place on the plot. If you’re wondering what calabrese is, it’s sold as broccoli in the supermarkets – the firm bright green heads that are delicious lightly steamed, stir-fried or made into a rich soup with blue cheese.

This misnaming has given rise to some confusion between calabrese and ‘true’ broccoli – a sprouting vegetable that’s enjoyed very early on in the year when pickings on the plot are otherwise thin. True broccoli overwinters while calabrese is sown, grown and harvested in the same year, completing its useful life cycle within four to five months, and often quicker than this.

Calabrese broccoli needs a rich, firm soil that isn’t acidic. You will need to ensure there is minimal root disturbance, which means sowing directly where it is to grow, or starting seedlings off in modules and pots, rather than transplanting. During the growing season, broccoli plants demand careful watering and a weed-free patch.

Protection against some of calabrese broccoli’s biggest pests, notably marauding pigeons and the cabbage white butterfly, is also likely to be necessary. Don’t be put off if all this sounds like too much fuss – despite appearances calabrese is still a relatively easy crop to grow and given these few precautions you’ll be picking good, solid heads of tightly-closed flower buds throughout late summer and autumn and cooking into tasty broccoli recipes before you know it.

Where does broccoli grow best?

Pick a sunny position on the vegetable plot for your calabrese. It is important to practice strict crop rotation to avoid potential pest and disease problems, as well as making the best use of your soil. Do not plant your plants where other members of the calabrese broccoli family, brassicas such as cabbage and Brussels sprouts, have grown in the past two years. If possible, follow the plants on from legumes such as peas.

Like all brassicas, calabrese broccoli prefers a firm, loamy soil that is full of nutrients. Prepare the ground the autumn or winter before sowing by digging it over then adding organic matter – about a barrow load of garden compost, leaf mould or manure per square metre should do the trick. Allow the worms to draw this into the ground over winter, before forking over the area the following spring.

If your soil is in any way acidic, you will need to apply some garden lime at this point. Add at least 100g per square metre, or considerably more if your soil has a particularly low pH. It is hard to add too much lime for your calabrese crop, so err on the side of excess if in doubt. The level should be at least pH 7.5 – that’s just above neutral.

Around one week before sowing or planting out, add a final boost of nutrients to the soil by sprinkling over some blood, fish and bonemeal – a general-purpose organic fertiliser that will give your young broccoli plants a strong start.

Growing broccoli in a greenhouse

Calabrese may be sown directly where it is to grow outdoors, or started off under cover in modules or pots. These broccoli plants hate root disturbance and sowing in this way reduces this risk. Sow directly in rows placed 45-60cm apart – the larger spacing will give bigger heads at harvest time.

Draw drills into finely raked soil approximately 1cm deep and sow the seed very thinly. Alternatively, station sow by dropping a few seeds every 25cm, which will allow an intercrop of quick-growing radishes, spinach or salads before the calabrese needs the extra room to start producing broccoli heads. Cover the seeds back over and moisten the rows using a watering can fitted with a rose.

To sow under protection into modules, drop a couple of calabrese seeds into each cell and cover over with 1cm of compost. Water from the base of the trays, so that the moisture is drawn up from below without unsettling the newly sown seeds. Sowings under glass or plastic can be made as early as March, while those outside should begin in April or a few weeks earlier given the added warmth and protection of a cloche. Sowing a small quantity every few weeks up to mid-June can be helpful in extending the broccoli harvesting season.

Seedlings should emerge within about 10 days at which point direct-sown crops may be thinned to an initial spacing of one plant every 10-25cm. Thin young calabrese plants further once they are 5-7cm high to leave one every 50cm. Try to leave the biggest, healthiest seedlings in place each time to give your broccoli crop the best possible start.

Module-sown calabrese can be potted on into their own individual 7-10cm plastic pots when they are big enough. Take extreme care not to disturb the roots – slide the seedlings out of their modules very gently and have pre-prepared pots ready to receive them. Fill containers with compost, making a hole that is the same size as the module’s rootball. When the young broccoli plants are about 10cm high and have a few adult leaves they can be transferred outside. This will be in June or early July. Set the brassicas in rows 45-60cm apart, leaving 50cm between plants within the row.

How to grow broccoli indoors

You may want to grow broccoli from scraps of your food waste, but this would be a fun project, rather than to get a productive return for your efforts. Gardeners hungry for a quick result from their calabrese should consider growing microgreens rather than for broccoli heads. Loved by top chefs the world over, these tender leaves add sparkle and flavour to sandwiches and salads, or as a garnish to soups and hot dishes.

For gardeners growing in limited space, and searching for ways to grow broccoli in pots indoors, this is a good solution. Microgreens, also called micro-leaves, are simply seedlings harvested at their first leaf stage. The time to harvest is astonishingly quick – as fast as five days and rarely longer than two weeks. The cress and mustard you probably grew as a child are microgreens.

The young seedlings of calabrese and broccoli have a gentle, peppery flavour that goes well with egg dishes or fish. Don’t waste expensive calabrese seed to grow your microgreens – instead buy purpose-sold broccoli microgreen seeds. Add a double-layer of kitchen paper into the bottom of an old food container, mist with water and then sow fairly thickly. Place the container on a light windowsill and keep moist. Harvest by snipping the greens at their base.

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Growing Calabrese month-by-month

January

Finish digging the soil ready for your calabrese broccoli and apply a thick application of organic matter to improve the soil's structure. Leave this on the ground for the worms to dig in.

Febraury

Order your calabrese seed. Look for vigorous varieties, particularly those that are described as being resistant to clubroot if it is a problem on your soil.

March

Begin preparing your plot for the calabrese broccoli sowings that follow next month. Fork over the ground and apply lime to raise the pH of the soil. Start sowing seed under cover.

April

Make outdoor sowings of your calabrese by the middle of the month or as soon as the ground allows. Sowings can be made at the start of April using cloches.

May

Continue sowing your calabrese every few weeks if you want a succession of broccoli heads. Thin germinated seedlings in stages to leave 50cm between plants.

June

Plant out young crops sown indoors under the protection of your greenhouse. Set them at generous spacings so that plenty of air can circulate between plants. Mulch, weed and water for a bumper broccoli harvest.

July

Continue watering and hoeing your calabrese crop regularly. Apply a mulch on the ground to lock in valuable soil moisture and protect broccoli heads against pests.

August

Keep your watering routine up throughout August when the weather is likely to be hot. Harvests from your calabrese can be used in nutritious broccoli recipes.

Must do this month!
September

Continue cutting heads as they are ready. Always cut before the tiny flowers open out. If you’ve got ample, add some of the broccoli to the freezer for use over the winter months.

October

Cutting will begin to slow by the end of the month – the plants are frost-tolerant but the broccoli flower heads are easily damaged by the coldest conditions.

November

Dig up spent calabrese plants and chop them up with secateurs before adding to the compost heap. Rake up any remaining crop debris from the ground.

December

If you haven't already done so, start digging over the ground for next year's broccoli crop. Choose a spot that hasn't had brassicas growing in it for a few years.

Caring for your Calabrese plants + problems

Once it is established it is genuinely growing calabrese broccoli is easy. However, it won’t take kindly to dry or nutrient-poor soils, which will only result in smaller broccoli heads.

Avoid this by weeding around plants carefully using a hoe and watering whenever the ground dries out. This is particularly important as the broccoli heads start to form. If your soil isn’t particularly rich you can give your crop an added bonus by forking in another light application of organic fertiliser when the plants are about 20cm tall.

To lock in moisture, consider laying a mulch of garden compost around calabrese plants, making sure it doesn’t touch the main stems. Watch out for your plant going to seed, usually from under-watering or feeding or as this plant enjoys cool weather, it may be from hot conditions. You’ll notice this when growing broccoli if it’s flowering with yellow flowers.

Pigeons are rather partial to the young broccoli plants, so you may have to drape netting over upturned pots supported on canes to protect them. The cabbage white butterfly might lay its eggs on the leaves. Pick the bugs off as soon as you notice them (crushing them under foot) or make sure any netting you install has a close enough gauge to exclude butterflies.

Calabrese will be ready from July through to the first frosts of late October and early November. Some particularly early varieties can be picked even sooner than this, giving a potential cropping period of around four months. Cut the broccoli heads when they are well developed but while the flower buds are still tightly closed, rather than after the plant has begun flowering.

How big does broccoli grow? Calabrese grows to around 60cm (2ft) in height, and this means that unlike their purple sprouting counterparts, these broccoli plants falling over is unlikely.

Varieties of Calabrese

Calabrese varieties to try

‘Broccoli (Autumn) Green’

A later-cropping variety, ‘Autumn Calabrese’ produced domed-shaped broccoli heads with medium-sized beads, followed by smaller edible sideshoots once the heads are cut.

‘Marathon’ F1 AGM

Reliable and long-cropping, this all-rounder calabrese produces tasty broccoli heads across the summer and into autumn. Shows good resistance to disease.

‘Kabuki’ Hybrid F1

If you want more bang for your buck, this hybrid calabrese variety means more broccoli harvests in a smaller space. It’s compact and produces results quickly.

'Fiesta' F1 Hybrid

This calabrese produces medium-sized broccoli heads with small buds set deep in the leaf. It’s a late-maturing type that will crop into October; great for extending the growing season.

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