What to plant in March in Ireland

Worked out for 14 cities from their own weather and frost dates, by zone.

What to sow and plant in March in Ireland, by zone: frost-free, highs of 10–16 °C (Athlone and Bray): broad bean, peas, onion, spinach, lettuce and 21 more; frost possible, highs of 10–16 °C (Galway, Limerick and 4 more): broad bean, peas, onion, spinach, lettuce and 21 more; frost possible, highs below 10 °C (Dublin, Cork and 4 more): broad bean, peas, onion, spinach, lettuce and 15 more.

In Ireland, March is spring.

Frost-free, highs of 10–16 °C: Athlone and Bray

In March, on average, these cities have highs of 10 °C and lows of 4 to 5 °C, 89 to 91 mm of rain on 15 to 16 days; the day lasts 11 h 47 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	all
plant sets	Onion, shallot	all
start indoors, plant out in April	Lettuce, cauliflower, chicory, kohlrabi	all
start indoors, plant out in May	Leek, parsley, Brussels sprouts	all

Compared with February: new — lettuce, carrot, chicory, daikon, dill, mustard greens, parsnip and shallot.

Not starting in March: 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 Athlone.

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

Frost possible, highs of 10–16 °C: Galway, Limerick, Waterford, Tralee and 2 more

In March, on average, these cities have highs of 10 to 11 °C and lows of 3 to 4 °C, 79 to 127 mm of rain on 14 to 18 days; the day lasts 11 h 47 min to 11 h 48 min (on the 15th).

March falls in the frost season: frost-tender crops wait. Average last frost: Galway (17 March), Limerick (13 March), Waterford (3 March), Tralee (23 March), Dundalk (20 March) and Navan (28 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
start indoors, plant out in April	Lettuce, cauliflower, chicory, kohlrabi	all
sow direct	Carrot, dill, mustard greens	Galway, Limerick, Waterford and 1 more
sow direct or start indoors, plant out in May	Broccoli	all
sow direct or start indoors, plant out in April	Beet	all
start indoors, plant out in May	Leek, parsley, Brussels sprouts	all

Compared with February: new — lettuce, carrot, daikon, parsnip, shallot, dill and mustard greens.

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

Frost possible, highs below 10 °C: Dublin, Cork, Kilkenny, Sligo and 2 more

In March, on average, these cities have highs of 9 to 10 °C and lows of 3 to 4 °C, 86 to 112 mm of rain on 15 to 18 days; the day lasts 11 h 46 min to 11 h 48 min (on the 15th).

March falls in the frost season: frost-tender crops wait. Average last frost: Letterkenny (30 March) and Mullingar (19 March).

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

Compared with February: new — lettuce, cauliflower, Swiss chard, beet, arugula, chamomile, chicory, kale and 1 more.

Ready to harvest in March in Kilkenny, 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).

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.