vegetable
brassica family

Broccoli

Brassica oleracea var. italica

Broccoli (specifically calabrese) is a fast-growing brassica that produces dense green heads packed with nutrients. It's one of the more straightforward brassicas to grow, maturing in as little as 12 weeks from transplanting. Sow under cover in March–April and transplant when seedlings have 4–5 true leaves, spacing 45cm apart. After cutting the main head, leave the plant in place — it will produce smaller side shoots for several more weeks of harvesting. 'Green Magic' and 'Ironman' are reliable F1 varieties. For winter harvests, grow purple sprouting broccoli instead — it's sown in spring but not harvested until the following February to April, filling the hungry gap when little else is fresh. All broccoli needs protection from cabbage white butterflies with fine netting, and firm soil to prevent wind rock.

Plan where to grow Broccoli using our vegetable garden planner.

SunlightFull sun
WateringModerate
Height60cm
Spacing45cm
Germination5–10 days
Sowing MethodUnder cover
Frost HardinessHalf-hardy
Sowing Depth1–2cm

When to Sow Broccoli

Sow broccoli in March, April, May, June.

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Sowing months

Time to Harvest Broccoli

Expect to harvest approximately 3 months after sowing.

Companion Plants

Expected Yield

Main head plus side shoots gives around 500g–1kg per plant.

Common Problems with Broccoli

Caterpillars

Cabbage white butterfly caterpillars can reduce broccoli leaves to skeletons within days. Cover plants with fine mesh netting (Enviromesh) immediately after transplanting — the mesh must be secure at ground level to prevent butterflies finding gaps. Check plants regularly and remove any eggs (small yellow clusters on leaf undersides) or caterpillars by hand.

Club root

A soil-borne disease causing swollen, distorted roots and stunted, wilting growth. Once in the soil, spores persist for up to 20 years. Lime acidic soils to raise the pH above 7.0, rotate brassicas on a strict 3–4 year cycle, and raise seedlings in modules with clean compost to give them a strong root system before planting into potentially infected ground.

Loose, open heads

Instead of forming a tight dome, the head opens loosely with visible floret stalks — usually caused by heat stress, insufficient watering, or transplanting too late in the season. Plant out promptly while seedlings are still young (4–5 true leaves), water consistently during head formation, and choose varieties suited to the sowing season to avoid maturing during the hottest weeks.

Plan your broccoli in the allotment planner

Drag and drop plants onto your plot and get personalised sowing reminders.

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More Vegetables

Cherry Tomato

Solanum lycopersicum var. cerasiforme

vegetable

Cherry tomatoes are one of the most rewarding crops for UK allotment growers. These small, sweet fruits ripen reliably even in cooler summers, producing heavy trusses from July right through to October. They thrive in grow bags, pots, or directly in the ground, making them versatile for any plot size. Pinch out side shoots regularly on cordon varieties to channel energy into fruit production. Bush varieties like 'Tumbling Tom' need no training and work brilliantly in hanging baskets. Feed weekly with a high-potash tomato feed once the first fruits set. The key to great flavour is letting them ripen fully on the vine rather than picking early.

Full sunModerate150cm

Beefsteak Tomato

Solanum lycopersicum

vegetable

Beefsteak tomatoes produce the large, meaty fruits that are perfect for slicing into sandwiches and burgers. They need a long growing season in the UK, so starting seeds early under cover is essential. These are almost always grown as cordons — train them up a single stem, removing side shoots weekly. Each truss produces fewer but much larger fruits than cherry types, often weighing 200–500g each. They benefit from greenhouse growing in cooler regions, though sheltered outdoor spots in the south can produce good results. Consistent watering is critical; irregular watering causes blossom end rot and fruit splitting. Stop the plant at 4–5 trusses to ensure fruits ripen before autumn.

Full sunModerate180cm

Nantes Carrot

Daucus carota

vegetable

Nantes carrots are the gold standard for flavour — sweet, crisp, and cylindrical with a smooth skin that barely needs peeling. They perform well in most UK soils but prefer light, stone-free ground to grow straight. If your soil is heavy clay, grow them in raised beds or deep containers filled with sandy compost. Sow thinly to avoid the need for heavy thinning, which attracts carrot fly. Cover rows with fine mesh or enviromesh as a physical barrier against carrot fly — this is far more reliable than companion planting alone. Successional sowing from March to July gives you carrots from June through to winter. Late sowings can be left in the ground over winter under a thick mulch of straw.

Full sunModerate30cm

Butterhead Lettuce

Lactuca sativa

vegetable

Butterhead lettuce produces soft, rounded heads with tender, buttery-textured leaves that melt in the mouth. It's one of the quickest salad crops to grow — ready in as little as 8 weeks from sowing. Unlike iceberg types, butterheads tolerate partial shade and are less likely to bolt in warm spells. Sow small batches every 2–3 weeks from March to September for a continuous supply. They work well as an intercrop between slower-growing vegetables like brassicas and leeks. Water consistently but avoid wetting the leaves to reduce the risk of grey mould. 'All the Year Round' is the classic UK variety and lives up to its name, performing well in almost every season.

Part shadeHigh20cm