GreenlyWhat to plant in May in Ireland
Worked out for 14 cities from their own weather and frost dates, by zone.
What to sow and plant in May in Ireland, by zone: frost-free, highs of 16–22 °C (Galway and Limerick): broad bean, peas, onion, spinach, lettuce and 21 more; frost-free, highs of 10–16 °C (Dublin, Cork and 10 more): broad bean, peas, onion, spinach, lettuce and 21 more.
In Ireland, May is spring.
Frost-free, highs of 16–22 °C: Galway and Limerick
In May, on average, these cities have highs of 16 °C and lows of 8 to 9 °C, 73 to 78 mm of rain on 14 days; the day lasts 15 h 45 min to 15 h 50 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, parsley, cilantro, arugula, chamomile, daikon, dill, kale, kohlrabi, mustard greens, parsnip, turnip | all |
| plant sets | Onion, shallot | all |
| start indoors, plant out in June | Cauliflower | all |
| start indoors, plant out in July | Leek, Brussels sprouts | all |
Compared with April: new — cilantro.
Not starting in May: tomato (no month outdoors by these rules), bell pepper (no month outdoors by these rules), zucchini (June, sown direct) and green beans (June, sown direct) — dates for Galway.
Ready to harvest in May in Galway, if sown in the right month: broad bean (February), peas (March), spinach (March), radish (April), carrot (March), cabbage (January), Swiss chard (March) and beet (March).
Frost-free, highs of 10–16 °C: Dublin, Cork, Waterford, Athlone and 8 more
In May, on average, these cities have highs of 15 to 16 °C and lows of 7 to 9 °C, 62 to 90 mm of rain on 12 to 15 days; the day lasts 15 h 39 min to 16 h 06 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, parsley, cilantro, arugula, chamomile, daikon, dill, kale, kohlrabi, mustard greens, parsnip, turnip | all |
| plant sets | Onion, shallot | all |
| start indoors, plant out in June | Cauliflower | all |
| start indoors, plant out in July | Leek, Brussels sprouts | all |
| start indoors, plant out in June | Chicory | Sligo and Letterkenny |
Compared with April: new — cilantro.
Not starting in May: tomato (no month outdoors by these rules), bell pepper (no month outdoors by these rules), zucchini (June, sown direct) and green beans (June, sown direct) — dates for Dundalk.
Ready to harvest in May in Dundalk, if sown in the right month: broad bean (February), peas (March), spinach (March), radish (April), cabbage (January), Swiss chard (March), arugula (April) and chamomile (March).
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).
Courgettes and French beans: GIY Ireland sows courgettes and succession-sows French beans outdoors in June, so we list them in June wherever June has no frost.
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.
- Moon planting calendar for May 2027
- What to plant in May: all climates
- Gardening in Ireland: guide by region
Other months in Ireland
- What to plant in May in the Northeast and Midwest
- What to plant in May in the South
- What to plant in May in Texas
- What to plant in May in Florida
- What to plant in May in California
- What to plant in May in the Pacific Northwest
- What to plant in May in the Southwest
- What to plant in May in the Mountain West
- What to plant in May in Canada
- What to plant in May in the UK
