Growing Broccoli in Scotland: The Complete Guide

Brassica oleracea (Italica Group)

Everything you need to grow broccoli in Scotland, from a February sowing on a windowsill to purple spears cut in the snow. We have done the research so you don't have to.

Broccoli, the sprouting kind, not the supermarket calabrese, is the crop that earns its keep by standing through winter and delivering fresh spears in February and March when almost nothing else is available. It is a brassica, which means it wants lime, wants mesh, and wants you to keep it away from the patch where cabbages grew last year. It takes eight months or more to reach its first harvest. A purple sprouting broccoli in the hungry gap, when the shops are selling imported greens and your plot has been bare since November, is worth every week of bed space it occupied.

Why broccoli suits Scotland

Broccoli prefers a cool summer. Hot weather can cause the flower buds to develop prematurely, reducing the crop. In much of England that is a risk worth managing. In Scotland it is barely a risk at all. A Scottish summer, cool and steady, is exactly what a broccoli plant wants. Our climate also holds down two of the difficult brassica pests: cabbage aphid and cabbage root fly are less troublesome here than further south. The plants mature more slowly, but they mature steadily.

The real Scottish advantage is winter. Traditional varieties are hardy and stand through the cold, providing harvests from winter into spring. A crop that wants a cool summer and holds through a Scottish winter is a crop that belongs here.

Varieties

Purple varieties are hardier and more productive than white, which is the trait that matters for a crop standing through a Scottish winter. These carry the RHS Award of Garden Merit, a UK-wide award, not a Scottish one.

Also worth considering

Soil and site

Broccoli wants fertile, well-drained soil in sun or very light shade. Choose a sheltered spot. These are tall plants, up to 90cm, and a winter gale will loosen them at the roots. Broccoli prefers a soil pH of 6 to 7. If your soil is very acidic, apply lime the winter before sowing to raise the pH and deter club root disease. This matters more in Scotland, where naturally acidic soils are common.

Dig in two bucketfuls of well-rotted manure or garden compost per square metre several months before planting, to let the ground settle. If done just before planting, firm the soil well by treading it down. Broccoli is a brassica, so rotate it with other cabbage-family crops and do not plant it where brassicas grew last year.

Sowing and planting

Sow from February to July: indoors from February, outdoors from April. Sow two seeds per module, 2cm deep, in peat-free seed compost. Germination takes about two weeks without additional heat. Thin to the strongest seedling per module. Sow small batches several weeks apart for regular pickings over a long season.

Plant out when the young plants are 10 to 15cm tall with a good root system. You can do this any time from mid-spring to late summer depending on the sowing date. Harden off indoor-raised plants first. Plant deeper than they were in the pot, with the lowest leaves at the soil surface, so they root deeply and firmly. Space plants 70cm apart depending on the variety, with a similar distance between rows. Generous spacing ensures good air circulation, which reduces disease, and encourages more side-shoots.

Starting plants in modules is also worth doing if you have club root in your soil. A well-developed root system before going into the ground means the plant is less severely affected.

Watering and care

Water young plants during dry spells until they are well established. After that, you should only need to water during prolonged dry weather. A thick mulch of garden compost around the plants retains moisture and suppresses weeds. If the soil is poor, apply an organic high-nitrogen fertiliser when the plants are about 20cm tall.

Weed regularly while the plants are young. Once the crop is growing strongly, the large leaves shade out most competition.

Support: broccoli plants are tall and top-heavy, and an exposed Scottish plot will loosen them at the roots. Pile soil up around the base of the stem to increase stability, and insert a sturdy cane tied to the main stem before the autumn gales arrive.

Protection: cover the crop with insect-proof mesh or fleece, supported on canes and pinned to the ground. Cabbage white butterflies, cabbage root fly and pigeons will all take a broccoli plant if it is not covered. The mesh is cheap, it stays on for the life of the crop, and it removes the need to patrol for caterpillars every day.

Harvesting

Broccoli is ready from June through to the following March, depending on sowing time and variety. Plants take four to ten months to start cropping, then provide pickings for up to two months. Summer varieties crop much faster than winter ones.

Harvest when the small heads or spears are well formed but still tightly in bud, before the yellow flowers open. Cut the whole shoot at the base with about 10cm of stem and any small leaves, which can all be eaten. Take the central spear first, then side-shoots will form over the following weeks. The more shoots you harvest, the more the plant produces. Check plants regularly. A spear in tight bud at breakfast is a yellow flower by dinner.

Purple varieties generally turn green when cooked. Broccoli is best used as fresh as possible but keeps in the fridge for a few days and freezes well. A winter broccoli standing through January into February, purple spears against the snow, is one of the most satisfying things in a Scottish garden.

Common problems

• Club root causes swollen, distorted roots. Plants wilt in dry weather. Lime the soil, start plants in modules to give them a head start, and rotate brassicas. No chemical treatment exists.
• Cabbage caterpillars are the larvae of cabbage white butterflies. They can strip a plant in days. Cover with insect-proof mesh from the start. If they get in, pick them off by hand.
• Cabbage root fly maggots eat the roots. Mesh is the defence. Less troublesome in Scotland's cool summers.
• Pigeons will strip a broccoli plant to the stem. Mesh or netting, from the day you plant out.
• Bolting means the plant flowers prematurely in hot weather, leading to a smaller crop. Far less of a problem in Scotland than further south. Harvest the early buds as soon as you see them.
• Plants loosening in wind. Stake them and mound soil around the stems. An exposed Scottish plot will test the roots.

Common questions

Sources