Brassica
How to grow broccoli (calabrese)
Brassica oleracea (Italica group)
The green-headed broccoli sold in shops is calabrese, a fast summer crop that is ready 12 to 16 weeks from sowing and is cut from late June to October. It is not the same plant as purple sprouting broccoli, which stands the winter. Sow in modules from March to June, plant into rich, firm, moist soil while the plants are still small, and cover with mesh at once. Any check from drought or a pot-bound root makes it bolt into small heads.
- Hardiness
- Not winter hardy; cut before hard frost
- Position
- Full sun
- Soil
- Rich, firm, moisture-retentive
- Ideal pH
- 6.5 to 7.5
- Water
- High, keep evenly moist
- Feeding
- Heavy feeder
Sowing and planting broccoli (calabrese)
WhenSow Mar to Jun; harvest Jun to Oct
Starting off
Sow 1 to 2 cm deep in modules at 15 to 20 °C from March (under cover) to June, germinating in 7 to 10 days; sow every 3 to 4 weeks for succession. Plant out at 4 to 5 weeks when 10 cm tall, firming well, and cover at once with mesh. Direct sowing in May at 3 seeds per station also works.
Spacing and planting
Plant 30 cm apart in rows 45 cm apart for a large central head, or 15 cm apart for smaller heads and more spears. Sow in modules rather than a seedbed, as it resents root disturbance and bolts. A single plant fills a 30 cm pot and crops well with steady water.
Varieties worth growing
- Ironman F1
- Heavy, domed, blue-green heads that hold well before opening. A dependable choice for summer and autumn cutting.
- Marathon F1
- The standard for late crops: sown in May or June, it tolerates cool autumn weather and gives a good second cut of side shoots.
- Belstar F1
- Medium heads followed by plenty of side shoots, so one planting crops for weeks. Performs well on organic plots.
- Monclano F1
- Bred with clubroot resistance, for gardens and allotments where the disease is in the soil.
- Apollo F1
- A sprouting type grown for a long succession of slender, tender stems rather than one big head; cut and it keeps producing.
Broccoli (calabrese) month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do.
- February
Nothing to do. Test the soil pH and lime if it is needed.
- March
Sow in modules under cover from mid month.
- April
Sow again. Plant out the first batch late in the month under mesh or fleece.
- May
Sow in modules or direct. Plant out. Top-dress the first planting.
- June
Last sowing, using a late variety. Cut the first heads at the end of the month. Water weekly in dry weather.
- July
Cut main heads while the buds are tight. Top-dress afterwards for side shoots. Plant out June sowings.
- August
Cut heads and side shoots. Keep the bed moist.
- September
Cut heads from late sowings. Check for caterpillars.
- October
Cut the last heads and shoots before hard frost. Pull up the stumps.
- November
Clear and compost remaining plants.
- December
Nothing to do.
Feeding broccoli (calabrese)
A hungry, fast crop that has to grow without a pause. Base dressing at planting, nitrogen three to four weeks later, and a dry top-dress after the main head is cut to bring on the side shoots.
A balanced-to-nitrogen-rich feed; keep watered for fat central heads followed by side shoots.
Feeding plan
A week before planting
Fruit & Vegetable Fertiliser 4-5-6
100 g/m² raked in and the bed firmed: about 14 g per plant at 30 by 45 cm (100 x 0.135 m²).
3 to 4 weeks after planting
Organic Nitrogen Fertiliser 13% N
40 g/m², the bottom of the label range for hungry brassicas: about 18 g per metre of row with rows 45 cm apart (40 x 0.45), watered in. Once.
After cutting the main head, once
Fruit & Vegetable Fertiliser 4-5-6
50 g/m² scattered along the row and watered in: about 7 g per plant at 30 by 45 cm (50 x 0.135 m²). With the base dressing that reaches the label's season limit of 150 g/m², so nothing more after it.
At planting, only where stems were hollow and brown inside last year
1 g/m², a quarter of a level teaspoon per square metre, scattered evenly, once a season. Never exceed 2 g/m²: boron is toxic in excess.
Late winter before planting, only if a test shows pH below 6.5
Garden Lime (calcium carbonate)
About 0.5 kg/m², raked in at least a month before any fertiliser.
Signs to watch
Hollow stems with brown, corky centres
Boron short on limed, light ground
Seaweed feed or a light borax dressing
Small heads running to yellow flower
A check from drought or heat after transplanting, not a nutrient shortage
Keep moist and plant young
Pale leaves and slow growth
Nitrogen short
Top-dress 3 to 4 weeks after planting
Pests, diseases and problems
Holes in the leaves and green caterpillars hidden among the florets
Caterpillars of cabbage white butterflies and cabbage moth
Grow under fine insect mesh from planting to harvest. Soak cut heads in salted water for ten minutes to float out any that got through.
Young plants pecked to stalks
Wood pigeons
The same mesh or netting, held on hoops and pegged down.
Transplants wilt and turn bluish; roots gone, with white maggots in the soil
Cabbage root fly
Brassica collars round each stem at planting, or mesh with the edges buried. Water wilting plants and earth up the stem so they can re-root.
Plants wilt in sun and make little growth; roots swollen and distorted
Clubroot
Lime acid soil to pH 7 or just above, improve drainage, raise plants in pots to give them a head start and grow Monclano F1.
Brown, wet, sunken patches spreading across the head in rainy weather
Head rot (spear rot), bacteria entering where water sits on the buds
Choose domed varieties that shed water, give the full spacing for air flow, go easy on nitrogen, and cut heads promptly with a sloping cut so the stump sheds rain.
Seedling leaves pitted with tiny holes
Flea beetle in dry spring weather
Keep seedlings under fleece and well watered until they are growing strongly.
Harvest and rotation
Harvest and storage
Cut the central head 12 to 16 weeks from sowing while the buds are tight and dark green, slicing 10 cm of stem with it. Side shoots follow for 4 to 6 weeks; cut at 10 cm. A plant gives a 300 to 500 g head plus 300 g of spears. Use within 3 days or blanch and freeze florets within hours of cutting.
Rotation and companions
Rotation: brassica group, 4-year gap, placed after legumes on limed ground. Dwarf French beans alongside fix nitrogen and cast no shade.
Good to knowCut the main head before it flowers to bring on a flush of secondary spears.
Growing broccoli (calabrese) in pots
Calabrese will crop in a pot if it never goes short of water. Grow one plant in a 30 cm pot (about 15 litres) of loam-based or good peat-free compost with the 4-5-6 mixed in at 5 g per litre, which is 75 g, and firm it well. Water daily in summer, cover with mesh, and top-dress once with the 4-5-6 at 2 g per litre, which is 30 g, watered in, when the head begins to form. Expect a smaller head than in open ground. A sprouting type such as Apollo F1 gives more to pick from a pot than a single-headed variety.
Broccoli (calabrese): common questions
What is the difference between broccoli and calabrese?
Calabrese is the correct name for the large green heads sold as broccoli in shops. It is a quick summer and autumn crop. Sprouting broccoli, purple or white, is a different, much hardier type that is planted in summer and gives many small spears the following February to April.
Why is my broccoli flowering before the head is big?
The plant has been checked, usually by dry soil, heat, or being held too long in its pot before planting. A stressed plant heads up early at a small size and the buds open into yellow flowers within days. Plant at four to five weeks old, keep the soil moist and cut heads while the buds are tight.
Does broccoli grow back after cutting?
Yes. After the main head is cut, most varieties produce smaller side shoots from the leaf joints for another four to six weeks. Cut the main head with about 10 cm of stem, leave the plant in place, top-dress with 50 g/m² of the 4-5-6 and water it in.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.
- How to grow calabreseRHS
- Club root in brassicas: prevention and treatmentRHS
- How to grow calabreseBBC Gardeners' World