What to plant in May in the UK

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

What to sow and plant in May in the UK, by zone: frost-free, highs of 16–22 °C (London, Manchester and 20 more): broad bean, peas, onion, spinach, lettuce and 33 more; frost-free, highs of 10–16 °C (Edinburgh, Glasgow and 15 more): broad bean, peas, onion, spinach, lettuce and 23 more; frost possible, highs of 10–16 °C (Inverness): broad bean, peas, onion, spinach, lettuce and 22 more.

In the UK, May is spring.

Frost-free, highs of 16–22 °C: London, Manchester, Birmingham, Bristol and 18 more

In May, on average, these cities have highs of 16 to 18 °C and lows of 7 to 9 °C, 51 to 92 mm of rain on 11 to 14 days; the day lasts 15 h 29 min to 15 h 57 min (on the 15th).

No frost in May 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, lettuce, radish, carrot, cabbage, broccoli, Swiss chard, beet, zucchini, green beans, parsley, cilantro, arugula, chamomile, dill, kale, kohlrabi, mustard greens, parsnip	all
plant sets	Onion, shallot	all
sow direct	Spinach	Manchester, Birmingham, Bristol and 15 more
start indoors, plant out in June	Cauliflower	all
start indoors, plant out in July	Leek	Manchester, Birmingham, Leeds and 7 more
start indoors, plant out in July	Bell Pepper, eggplant, chili pepper, moringa	London, Southampton, Oxford and 4 more
start indoors, plant out in June	Cucumber, melon, watermelon, pumpkin, basil, achocha, kiwano, peanut	London, Bristol, Leicester and 9 more
sow direct or start indoors, plant out in June	Sweet Corn, bok choy, Napa cabbage	London, Bristol, Leicester and 9 more
start indoors, plant out in July	Brussels Sprouts	all
sow direct	Daikon	Manchester, Birmingham, Bristol and 18 more
sow direct	Chickpea	London, Bristol, Leicester and 9 more
sow direct or start indoors, plant out in July	Florence fennel	London, Southampton, Oxford and 4 more
sow direct	Borage, chayote, corn	London

Compared with April: new — green beans, cilantro, chickpea, borage and corn; no longer sown — tomato, celeriac, celery and turnip.

Not starting in May: tomato (March, started indoors) — dates for Leicester.

Ready to harvest in May in Leicester, if sown in the right month: broad bean (February), peas (March), spinach (March), radish (April), Swiss chard (March), arugula (April), chamomile (March) and daikon (March).

Frost-free, highs of 10–16 °C: Edinburgh, Glasgow, Belfast, Liverpool and 13 more

In May, on average, these cities have highs of 14 to 16 °C and lows of 6 to 11 °C, 45 to 83 mm of rain on 9 to 15 days; the day lasts 15 h 26 min to 16 h 30 min (on the 15th).

No frost in May 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, lettuce, radish, carrot, cabbage, broccoli, Swiss chard, beet, zucchini, green beans, parsley, cilantro, arugula, chamomile, daikon, dill, kale, kohlrabi, mustard greens, parsnip	all
plant sets	Onion, shallot	all
start indoors, plant out in June	Cauliflower	all
start indoors, plant out in July	Leek	Edinburgh, Glasgow, Belfast and 13 more
start indoors, plant out in July	Bell Pepper, eggplant, chili pepper, Florence fennel, moringa	Ipswich
start indoors, plant out in June	Cucumber, melon, watermelon, pumpkin, sweet corn, basil, achocha, bok choy, kiwano, Napa cabbage, peanut	Ipswich
start indoors, plant out in July	Brussels Sprouts	all
sow direct	Turnip	Edinburgh, Glasgow, Belfast and 8 more
start indoors, plant out in June	Chicory	Plymouth, Aberdeen, Stirling and 1 more
sow direct	Chickpea	Ipswich

Compared with April: new — green beans, cucumber, melon, watermelon, pumpkin, sweet corn, cilantro, basil and 6 more; no longer sown — tomato, celeriac, celery and chayote.

Not starting in May: tomato (March, started indoors) — dates for Derry.

Ready to harvest in May in Derry, if sown in the right month: broad bean (February), peas (March), spinach (March), radish (April), cabbage (January), arugula (April), dill (April) and mustard greens (April).

Frost possible, highs of 10–16 °C: Inverness

In May, on average, Inverness has highs of 15 °C and lows of 6 °C, 72 mm of rain on 13 days; the day lasts 16 h 34 min (on the 15th).

May falls in the frost season: frost-tender crops wait. Average last frost: Inverness (1 May).

How	What	Where
sow direct	Broad bean, peas, spinach, lettuce, radish, carrot, cabbage, broccoli, Swiss chard, beet, parsley, cilantro, arugula, chamomile, daikon, dill, kale, kohlrabi, mustard greens, parsnip, turnip	Inverness
plant sets	Onion, shallot	Inverness
start indoors, plant out in June	Cauliflower, zucchini	Inverness
start indoors, plant out in July	Leek, Brussels sprouts	Inverness

Compared with April: new — cilantro; no longer sown — tomato.

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

Ready to harvest in May in Inverness, if sown in the right month: peas (March), spinach (March), radish (April), arugula (April), dill (April), mustard greens (April) and turnip (March).

Frost dates in Inverness

How we work it out

For each city we use its average weather in May 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 May 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.