What to plant in March in the UK

Worked out for 40 cities from their own weather and frost dates, by zone.

What to sow and plant in March in the UK, by zone: frost possible, highs of 10–16 °C (London, Bristol and 19 more): broad bean, peas, onion, spinach, lettuce and 20 more; frost-free, highs of 10–16 °C (Swansea): broad bean, peas, onion, spinach, lettuce and 21 more; frost-free, highs below 10 °C (Brighton): broad bean, peas, onion, spinach, lettuce and 16 more; frost possible, highs below 10 °C (Manchester, Edinburgh and 15 more): broad bean, peas, onion, spinach, lettuce and 16 more.

In the UK, March is spring.

Frost possible, highs of 10–16 °C: London, Bristol, Leeds, Cardiff and 17 more

In March, on average, these cities have highs of 10 to 11 °C and lows of 3 to 7 °C, 53 to 106 mm of rain on 13 to 16 days; the day lasts 11 h 47 min to 11 h 49 min (on the 15th).

March falls in the frost season: frost-tender crops wait. Average last frost: Cardiff (25 March), Hull (28 March), Plymouth (1 March), Norwich (31 March), Ipswich (15 March) and Portsmouth (4 March).

How	What	Where
sow direct	Broad bean, peas, spinach, radish, cabbage, Swiss chard, arugula, chamomile, daikon, kale, parsnip, turnip	all
plant sets	Onion, shallot	all
sow direct or start indoors, plant out in April	Lettuce, beet	all
sow direct	Carrot, dill, mustard greens	London, Bristol, Cardiff and 6 more
sow direct or start indoors, plant out in May	Broccoli	all
start indoors, plant out in April	Cauliflower, kohlrabi	all
start indoors, plant out in May	Leek	Leeds, Cardiff, Liverpool and 5 more
start indoors, plant out in June	Tomato	all
start indoors, plant out in May	Bell Pepper, eggplant, chili pepper, Florence fennel, moringa	London
start indoors, plant out in May	Parsley, Brussels sprouts	all
start indoors, plant out in June	Celeriac, celery, chayote	London, Bristol, Leicester and 10 more
start indoors, plant out in April	Chicory	Plymouth

Compared with February: new — carrot, tomato, bell pepper, eggplant, daikon, parsnip, shallot, dill and 4 more.

Not starting in March: zucchini (April, started indoors) and green beans (May, sown direct) — dates for Bristol.

Ready to harvest in March in Bristol, if sown in the right month: broad bean (December), peas (January), radish (February) and cabbage (November).

Frost-free, highs of 10–16 °C: Swansea

In March, on average, Swansea has highs of 10 °C and lows of 5 °C, 126 mm of rain on 17 days; the day lasts 11 h 48 min (on the 15th).

No frost in March in 10 years of data: frost-tender crops can go in too, if it is warm enough for them.

How	What	Where
sow direct	Broad bean, peas, spinach, radish, carrot, cabbage, broccoli, Swiss chard, beet, arugula, chamomile, daikon, dill, kale, mustard greens, parsnip, turnip	Swansea
plant sets	Onion, shallot	Swansea
start indoors, plant out in April	Lettuce, cauliflower, kohlrabi	Swansea
start indoors, plant out in May	Leek, parsley, Brussels sprouts	Swansea
start indoors, plant out in June	Tomato	Swansea

Compared with February: new — lettuce, carrot, tomato, daikon, dill, mustard greens, parsnip and shallot; no longer sown — chicory.

Not starting in March: bell pepper (no month outdoors by these rules), zucchini (April, started indoors) and green beans (May, sown direct) — dates for Swansea.

Ready to harvest in March in Swansea, if sown in the right month: broad bean (December), peas (January), spinach (January), radish (February), cabbage (November) and broccoli (December).

Frost dates in Swansea

Frost-free, highs below 10 °C: Brighton

In March, on average, Brighton has highs of 9 °C and lows of 7 °C, 66 mm of rain on 12 days; the day lasts 11 h 49 min (on the 15th).

No frost in March in 10 years of data: frost-tender crops can go in too, if it is warm enough for them.

How	What	Where
sow direct	Broad bean, peas, spinach, radish, cabbage, broccoli, turnip	Brighton
plant sets	Onion	Brighton
start indoors, plant out in April	Lettuce, cauliflower, Swiss chard, beet, arugula, chamomile, chicory, kale, kohlrabi	Brighton
start indoors, plant out in May	Leek, parsley, Brussels sprouts	Brighton
start indoors, plant out in June	Tomato	Brighton

Compared with February: new — lettuce, cauliflower, Swiss chard, beet, tomato, arugula, chamomile, chicory and 2 more.

Not starting in March: bell pepper (no month outdoors by these rules), zucchini (April, started indoors) and green beans (May, sown direct) — dates for Brighton.

Ready to harvest in March in Brighton, if sown in the right month: broad bean (December), peas (January), spinach (January), radish (February), cabbage (November) and broccoli (December).

Frost dates in Brighton

Frost possible, highs below 10 °C: Manchester, Edinburgh, Birmingham, Glasgow and 13 more

In March, on average, these cities have highs of 8 to 10 °C and lows of 1 to 4 °C, 60 to 104 mm of rain on 14 to 17 days; the day lasts 11 h 44 min to 11 h 48 min (on the 15th).

March falls in the frost season: frost-tender crops wait. Average last frost: Derry (23 March).

How	What	Where
sow direct or start indoors, plant out in April	Broad bean, spinach	all
sow direct	Peas, radish	all
plant sets	Onion	Manchester, Edinburgh, Birmingham and 12 more
start indoors, plant out in April	Lettuce, cauliflower, Swiss chard, beet, arugula, chamomile, kale, kohlrabi	all
sow direct or start indoors, plant out in May	Cabbage	all
start indoors, plant out in May	Broccoli, leek, parsley, Brussels sprouts	all
start indoors, plant out in June	Tomato	all
sow direct	Turnip	Manchester, Edinburgh, Birmingham and 12 more
start indoors, plant out in April	Chicory	Edinburgh, Glasgow, Belfast and 7 more

Compared with February: new — lettuce, cauliflower, Swiss chard, beet, tomato, arugula, chamomile, kale and 2 more.

Not starting in March: bell pepper (no month outdoors by these rules), zucchini (April, started indoors) and green beans (May, sown direct) — dates for Edinburgh.

Ready to harvest in March in Edinburgh, if sown in the right month: broad bean (December), peas (January), radish (February) and cabbage (November).

How we work it out

For each city we use its average weather in March and the months after (highs, lows and rain for 2016–2025, ERA5 reanalysis via Open-Meteo) and its average frost dates. A crop starts in March if the month's mean temperature reaches the minimum soil temperature for germination on its card (we use the mean air temperature as a stand-in for the soil's) and if, over its first months (up to three), the average highs stay within its group's range, with no frost for crops that cannot take it. Crops started indoors count from the month they are planted out.

Temperature groups from Colorado State University Extension: cool-season crops prefer 16–27 °C and lose quality in heat; hardy ones grow in days as cool as 4 °C, semi-hardy ones from 4–10 °C (we use 10 °C); warm-season crops need days above 13 °C, and the most tender (tomato, pepper, aubergine, melon, watermelon, squash) above 16 °C, up to 35 °C. Crops the guide does not name go into the stricter group by their frost hardiness. Broad beans, which the guide does not name, count as hardy: hardy varieties are sown in autumn and overwinter (RHS). Garlic and bulbs: a month before the first frost, and later only while the ground is not frozen (as on each city's page). French beans, courgettes and outdoor tomatoes follow the RHS instead, in months without frost: French beans and courgettes sown outdoors in late May or early June, courgettes also started indoors in April or May; tomatoes started indoors from late March to early April and planted out in June where its average highs reach 16 °C.

This is a general rule from averages: your garden can be a week or two earlier or later, and a greenhouse or a cold frame brings the season forward. Greenly works out the dates for your location.