For February indoor sowing, the best brassicas are early summer cabbages, calabrese (broccoli), cauliflower, and Brussels sprouts, with specific varieties chosen for their maturity times and cold tolerance. Starting these seeds indoors gives them a head start on the growing season, allowing you to transplant sturdy seedlings once the soil warms and the risk of hard frost has passed.
Why Sow Brassicas Indoors in February
February is still winter in most temperate regions, but the days are lengthening and the soil is slowly warming. Sowing brassicas indoors at this time serves two main purposes: it extends the growing season for slow-maturing crops, and it protects young seedlings from the cold, wet conditions that can cause damping-off disease and slug damage outdoors. By the time April arrives, these indoor-started plants are weeks ahead of direct-sown seeds, giving you an earlier and more reliable harvest. This is particularly important for crops like cauliflower and Brussels sprouts, which need a long, cool growing period to form good heads or sprouts.
Which Brassicas Benefit Most from Early Sowing
Not all brassicas need an indoor start, but several benefit greatly from February sowing. The key is to choose varieties that are suited to early planting and that will not bolt (run to seed) if they experience a cold snap after transplanting.
- Early Summer Cabbage: Varieties like ‘Greyhound’ or ‘Hispi’ are quick-maturing and can be sown in February for planting out in March or April. They produce compact, pointed heads and are ready by early summer.
- Calabrese (Broccoli): Sow in February for an early summer crop. Choose varieties like ‘Green Magic’ or ‘Piracicaba’ that are known for good head formation in cooler conditions.
- Cauliflower: This is the trickiest brassica to start early. Choose an early variety like ‘All The Year Round’ or ‘Snowball’ and sow in February for planting out in April. They need consistent moisture and cool temperatures to avoid buttoning (producing tiny, useless heads).
- Brussels Sprouts: For an autumn crop, sow in February. Early varieties like ‘Red Rubine’ or ‘Falstaff’ can be started now, but they must be transplanted by May to avoid a long, leggy growth.
How to Sow Brassicas Indoors
The process is straightforward but requires attention to a few details.
- Use modular trays or small pots: Fill with a good quality seed compost. Brassicas do not like root disturbance, so individual modules or pots are best.
- Sow seeds shallowly: Place one or two seeds per module, about 1 cm (0.5 inch) deep. Cover with compost and firm gently.
- Water from below or with a fine rose: Keep the compost moist but not waterlogged. Use tap water that has been allowed to stand to reach room temperature.
- Provide warmth: Most brassicas germinate best at 15–20°C (59–68°F). A heated propagator or a warm windowsill works well. Once seedlings appear, move them to a cooler, bright spot (around 10–15°C / 50–59°F) to prevent them from becoming leggy.
- Thin to one seedling per module: After germination, remove the weaker seedling, leaving the strongest one.
- Harden off before planting out: About two weeks before transplanting, gradually acclimatise the seedlings to outdoor conditions by placing them outside for increasing periods during the day.
Choosing the Right Varieties for February
Variety selection is critical. Look for descriptions that mention ‘early’, ‘fast maturing’, or ‘cold tolerant’. Avoid maincrop or storage varieties, which are better sown later (March–May) for autumn and winter harvests. For example, ‘January King’ cabbage is a winter variety, not suitable for February sowing. Instead, choose ‘Spring Hero’ or ‘Primero’ for a spring crop. For cauliflower, ‘Amazing’ and ‘Freedom’ are reliable early types. For Brussels sprouts, ‘Peer Gynt’ and ‘Maximus’ are early maturing and can be sown in February, but they will need a long season and plenty of space.
Common Problems and How to Avoid Them
Indoor sowing has its own set of challenges.
- Leggy seedlings: This happens when seedlings do not get enough light or are kept too warm. Place them in a south-facing window or under grow lights, and keep them cool after germination.
- Damping-off: A fungal disease that causes seedlings to rot at the base. Prevent it by using clean pots, fresh compost, and avoiding overwatering. Good air circulation also helps.
- Bolting: If seedlings are exposed to temperatures below 10°C (50°F) for a prolonged period, they may bolt. Harden off gradually and do not plant out too early.
- Clubroot: This soil-borne disease affects brassicas. If you have had it before, avoid planting brassicas in the same spot for at least 3–4 years and lime the soil to raise pH.
Planting Out and Aftercare
Once your seedlings have 4–6 true leaves and the soil has warmed, usually in April or May, they can be transplanted. Harden them off for 7–10 days first. Plant them in a sunny, sheltered spot with fertile, well-drained soil. Space them according to the variety: cabbages 30–45 cm apart, cauliflowers 45–60 cm, Brussels sprouts 60–75 cm. Water well after planting and keep them consistently moist. Use a nitrogen-rich fertiliser after they are established, and protect from pigeons and cabbage white butterflies with netting or fleece.
Frequently Asked Questions
Can I sow all brassicas indoors in February?
No, only early varieties that are suited to a long growing season. Maincrop and winter varieties are better sown later, as they would mature too early and may bolt or become woody.
What if I don’t have a greenhouse or heated propagator?
A bright windowsill in a cool room works fine. The key is to keep the seedlings cool after germination and provide plenty of light. If you have a cold frame, you can use that for hardening off.
How long does it take for brassica seeds to germinate?
Most brassicas germinate in 5–10 days at 15–20°C. Some, like cauliflower, may take a little longer. Be patient and keep the compost moist but not wet.
Should I pinch out the growing tip of Brussels sprouts?
Some gardeners pinch out the top of Brussels sprouts in late summer to encourage the sprouts to swell. This is optional and not necessary for all varieties. Check the seed packet for specific advice.
Can I sow brassicas in February directly outdoors?
In most temperate climates, it is too cold and wet for direct sowing in February. The soil is often too cold for germination, and seedlings may be killed by frost. Indoor sowing is the reliable method for an early start.
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