Brussels sprouts are the slowest crop most of us grow, and the most rewarding to get right. Sown in spring, they stand in the ground for seven or eight months before the first button is picked — and then they keep giving from October through to February, in weather that has shut down almost everything else in the vegetable garden. Brassica oleracea var. gemmifera is the same species as cabbage and kale; the difference is where it puts its energy. Instead of one head at the top, it grows a tall stem and packs a small cabbage into every leaf joint. Almost every problem people have with sprouts comes back to that stem: how firmly it is anchored, how fast it grows, and when you stop it growing. Here is how to grow Brussels sprouts from seed, from a March sowing to a frosted December harvest.
- Sow March–May in modules or a seedbed, 1 cm deep
- Plant out May–June, 60–75 cm apart, into very firm soil
- Harvest October–February, from the bottom of the stem up
- Watch for loose 'blown' sprouts, wind rock, aphids, pigeons
What makes a Brussels sprout different
Every brassica has a bud in the angle where each leaf meets the stem. In cabbage those buds stay dormant; in gemmifera ('bud-bearing') they swell into the tight miniature heads we eat. The plant builds them from the bottom up, so the lowest sprouts are ready first and the top of the stem is still producing weeks later. That is why sprouts are picked a few at a time over months rather than cut once — and why the plant needs a long, steady season. A stem that grows too fast, sits in loose soil or gets rocked by autumn gales produces open, leafy buttons instead of hard ones. Gardeners call these 'blown' sprouts, and they are the most common complaint with the crop.
The same species gives us cabbage, kale, cauliflower and broccoli — browse the whole family in Brassica oleracea — so everything below about firm ground, netting and rotation applies across the brassica bed.
When and how to sow Brussels sprouts
Sow from March to May. Early F1 varieties can go in from late February under glass for a first picking in September; the traditional late varieties are best sown in April for a harvest that starts after the first frosts. Everything tagged for those months is in the March and April sowing collections.
- Modules are easiest — two seeds per cell, 1 cm deep, thinned to the strongest. A cold frame or unheated greenhouse is plenty; seed germinates in 5–10 days at 10–20 °C. Our guide to germinating seeds covers the basics.
- Or a nursery seedbed — the old way: a short drill outdoors from April, seedlings lifted and moved once they are 10–15 cm tall.
- Keep them cool — brassica seedlings on a warm windowsill stretch within days. Give them full light and move them out as soon as they are up; see leggy seedlings: causes and fixes.
Planting out: firm, deep and wide
Plant out after five or six weeks, when the young plants have four or five true leaves, hardened off for a week first. Three things decide the harvest in November:
- Firm ground — sprouts want soil that has settled, not a bed dug the week before. Tread it well before planting and firm around each plant with your heel. If you tug a leaf and the plant moves, it is not firm enough. A bed prepared the previous autumn, or a no-dig bed, is ideal.
- Plant deep — set the seedling so the lowest leaves sit just above the soil. A deeper stem is a steadier stem.
- Give them room — 60 cm apart for compact F1s, up to 75 cm for tall heritage types. Crowded plants grow thin and set small sprouts. Lettuce or radish can fill the gaps for the first two months.
Sprouts prefer rich, moisture-retentive soil with a pH around 6.5–7.5 — slightly alkaline soil also discourages clubroot. Our guide to preparing your soil covers liming, and brassicas follow legumes in a four-bed rotation to make use of the nitrogen peas and beans leave behind.
Summer and autumn care
Through summer the job is steady growth. Water deeply in dry spells — a check in July shows up as small, loose sprouts in November. Feed sparingly: a balanced feed or compost mulch in early summer is enough, and heavy nitrogen late in the season produces lush, soft growth and blown buttons. See feeding and fertilising plants for what 'balanced' means in practice.
From September, the plants are top-heavy. Draw soil up around the base of each stem and, on exposed sites, tie tall varieties to a stout cane or stake — the plant supports guide shows simple options. As the lower leaves yellow, snap them off: it improves airflow around the sprouts and removes hiding places for aphids and whitefly.
Harvesting: frost, picking order and topping
Start picking when the lowest sprouts are firm and about the size of a walnut. Snap them downwards or cut them with a knife, working up the stem and taking only what is ready. A well-grown plant yields for eight to twelve weeks.
Frost helps. Cold makes the plant convert stored starch into sugars, so sprouts picked after a few hard frosts taste noticeably sweeter and nuttier. That is not folklore — it is the same mechanism that sweetens kale, parsnips and savoy cabbage.
Topping, or 'stopping', is an October decision. Pinching out the growing tip tells the plant to stop making new sprouts and fill out the ones it has, so the whole stem matures at roughly the same time. It suits early varieties and anyone who wants one big picking for the freezer or Christmas. Do not top late varieties you want to pick over the whole winter — they need that growing point to keep producing. The leafy sprout top itself is a delicious green, cooked like cabbage.
How to grow Brussels sprouts from seed: step by step
- March–May: sow Two seeds per module, 1 cm deep, in a cold frame or cool greenhouse. Thin to one.
- Prepare the bed early Weed, add compost, lime if acid, then let the soil settle for several weeks. Tread it firm.
- May–June: plant out 60–75 cm apart, lowest leaves at soil level, firmed hard with your heel. Water in well.
- Net immediately Fine insect mesh on hoops keeps out cabbage white butterflies, pigeons and most aphids all season.
- June–August: water and weed Steady moisture, light feeding, no late nitrogen. Hoe carefully — the roots are shallow.
- September–October: earth up and stake Mound soil around the stems, stake tall plants, remove yellow leaves. Top early varieties now if you want an even harvest.
- October–February: pick from the bottom A few firm sprouts per plant per week; finish with the sprout tops.
Heritage or F1: which varieties to grow
Our Brussels sprout range splits cleanly into two groups, plus one curiosity.
Heritage, open-pollinated
Tall, late, strong-flavoured — Groninger and Roodnerf, old Dutch types.
- Sow April–May, pick November–February
- Sprouts mature over a long period
- Fuller, more traditional 'sprouty' taste
- Seed can be saved (with care)
F1 hybrids
Uniform, compact, milder — Igor, Topline, Cryptus and organic Doric.
- Sow February–May depending on variety
- Firm, even buttons, fewer blown sprouts
- Bred for sweeter, less bitter flavour
- Shorter, steadier stems
The curiosity is flower sprouts: a Brussels sprout crossed with kale, producing small, frilly green-and-purple rosettes up the stem instead of tight buttons. Grow them exactly like sprouts, sown April–May. For a certified-organic crop there is organic Doric F1 in our organic Brussels sprouts collection. If you are unsure which route suits you, heirloom vs F1 vs organic explains the trade-offs.
Common Brussels sprout mistakes
- Planting into freshly dug soil — the single biggest cause of blown, open sprouts. Firm, settled ground every time.
- Too much nitrogen, too late — soft, fast growth in late summer gives loose buttons. Feed early, then stop.
- Skipping the netting — caterpillars in summer and pigeons in winter can strip a crop. Mesh, not fleece, from planting day. Our pests guide covers mealy cabbage aphid and whitefly too.
- Planting too close — 30 cm between sprouts is cabbage spacing. They need twice that.
- Topping late varieties — you end their season early. Only stop the plants you want to clear in one go.
- Growing them in the same bed every year — clubroot builds up in the soil and lasts for decades. Rotate.
Frequently asked questions
When should I sow Brussels sprouts?
March to May. Sow early F1 varieties in late February or March under glass for picking from September; sow late heritage varieties in April for picking from November through winter. Sowing after May rarely gives a worthwhile crop.
Do Brussels sprouts need frost?
They do not need it to grow, but they taste better after it. Frost triggers the plant to turn starch into sugar, which is why sprouts picked in December are sweeter than those picked in September. The plants themselves are hardy to well below freezing.
Why are my Brussels sprouts loose and leafy?
Almost always loose soil, wind rock or late nitrogen. Plant into firm ground, set plants deep, stake and earth up in autumn, and stop feeding by midsummer. Some older varieties are also naturally looser than modern F1s.
Should I remove the leaves or the top of the plant?
Remove lower leaves as they yellow — it helps airflow and discourages pests. Only remove the top (topping) if you want all the sprouts to mature together; leave it on late varieties you plan to pick through winter.
Brussels sprouts ask for patience and a firm heel, and repay both with fresh greens in the darkest weeks of the year. Sow them next spring alongside the rest of the leafy brassicas, and in the meantime see what to sow in October for the beds that are emptying now. Browse all our vegetable seeds and the organic range, or start from our complete guide to growing vegetables and the rest of our growing guides.
