Northern Ireland

What to sow in Belfast

Belfast's position on Belfast Lough and the Gulf Stream influence give it a milder, more maritime climate than its latitude suggests. Frosts are less severe than eastern Britain at the same latitude, and the growing season is surprisingly generous.

Last frost date3 MayEstimated average

First autumn frost6 OctoberEstimated average

Growing season156 daysFrost-free period

March 2026

What to sow in Belfast right now

Based on a last frost date of 3 May, these are the crops you can get going in Belfast this month.

Broad beansPinch out the growing tips once the first pods form to discourage blackfly. They'll also ripen faster.

Sow indoorsDirect sow

PeasSow every 3 weeks for a continuous harvest. Pick regularly to keep them producing — leave one pod on and the whole plant slows down.

Sow indoorsDirect sow

LettuceSow a short row every 2 weeks and you'll never buy a supermarket bag again. Pick outer leaves to keep it going.

Sow indoors

SpinachBolts the moment it gets hot. Best in spring and autumn. Pick little and often — a whole plant cooks down to about two mouthfuls.

Direct sow

Onion setsPush sets into the soil with the tip just showing. Easiest way to grow onions — skip seed unless you enjoy waiting.

Direct sow

Potatoes (early)Chit (sprout) seed potatoes on a windowsill before planting. Earth up as they grow — if you see green skin, it's toxic.

Direct sow

KaleGets sweeter after a frost. One of the hardiest crops — can harvest all winter.

Sow indoors

LeeksDrop seedlings into deep holes and just water in — no need to fill the hole. They'll fatten up on their own.

Sow indoors

BroccoliCut the main head first and you'll get side shoots for weeks. Purple sprouting is the real star — worth the long wait.

Sow indoors

CabbageDifferent varieties for each season — spring, summer, autumn, and winter types. Red cabbage is less bothered by caterpillars.

Sow indoors

CauliflowerFold outer leaves over the curd to keep it white. Cauliflower leaves are delicious too — don't throw them away.

Sow indoors

Brussels sproutsGrow through summer, harvest from autumn through winter. Flavour improves after frost. Start early — they're slow.

Sow indoors

ParsleySlow to germinate (3-4 weeks) — don't give up on it. Soak seeds overnight in warm water to speed things up. Flat-leaf has the stronger flavour.

Sow indoors

SweetcornPlant in a block, not a row — they're wind-pollinated and need neighbours. Each plant gives you 1-2 cobs, so don't be stingy with numbers.

Sow indoors

CelerySow seeds on the surface — they need light to germinate. Start early in a propagator. Cutting celery is much easier than trench celery if you're new to it.

Sow indoors

TomatoesPinch out side shoots on cordon types. Feed weekly with tomato feed once the first truss sets. Don't overwater — flavour comes from a bit of stress.

Sow indoors

PeppersStart early — they're slow growers. Pinch out the first flower to encourage bushier growth and more fruit overall.

Sow indoors

ChilliesNeed heat to germinate — use a propagator or the warmest windowsill you've got. The more sun they get, the hotter the fruit.

Sow indoors

CucumbersOutdoor varieties are tougher and easier than greenhouse ones. Keep picking and they keep producing — ignore them and they swell to marrow size.

Sow indoors

AubergineStart very early — January isn't too soon. Limit to 5-6 fruits per plant if you want decent-sized aubergines rather than marbles.

Sow indoors

BasilPinch out flower buds to keep leaves coming. Harvest from the top to encourage bushy growth. Loves heat — don't even think about putting it outside before June.

Sow indoors

Full year