The short answer: most of Ireland is frost free by mid-May. But if you're in the midlands, the north or on higher ground, it's worth waiting until the last week of May before putting tender plants outside.
Every year, the same question surfaces in Irish gardening circles around the first of May. Is the frost risk over? Can the tomatoes go outside yet? Is it safe to plant out the seedlings that have been sitting on the windowsill since March?
The honest answer depends on where in Ireland you are. This guide gives you a clear, regional breakdown so you can stop second guessing and start planting.
Ireland's Last Frost Dates by Region
Ireland doesn't have one frost date, it has several, depending on where you live. Cold air pools in inland areas and on higher ground long after coastal spots are safely clear.
| Region | Last frost (typical) | Notes |
| Coastal south (Cork, Wexford, Waterford) | Late April – early May | Earliest to clear. Often frost-free by end of April in sheltered spots. |
| Dublin and east coast | Mid-May | Generally safe from mid-May. Watch for cold snaps after clear nights. |
| West coast (Galway, Clare, Mayo) | Mid-May | Mild but windy. Frost risk low by mid-May in most areas. |
| Midlands (Offaly, Laois, Roscommon) | Late May | Cold air pools inland. Wait until end of May for tender plants. |
| North (Donegal, Cavan, Monaghan) | Late May | Last to clear. High ground can still frost into early June. |
| Higher ground anywhere | End of May – early June | Elevation adds risk. Always check local forecast regardless of region. |
The rule of thumb: if you're not sure, wait another week. A week's patience now is far less costly than losing a tray of seedlings to a late frost.
What Does Frost Risk Actually Mean for Your Plants?
Not all plants are equally vulnerable. Understanding which plants need protection helps you make smarter decisions rather than following blanket rules.
Hardy plants: Safe to plant out now (even before mid-May)
These plants tolerate light frost and can go outside throughout May in most parts of Ireland:
- Sunflowers (direct sow outdoors)
- Peas and broad beans
- Carrots, beetroot, spinach, kale
- Lettuce and salad leaves
- Cornflowers and other hardy annual flowers
- Radishes — fastest-growing and completely frost-hardy
Tender plants: Wait until frost risk has passed
These plants cannot tolerate frost and should stay indoors or in a sheltered spot until your local area is reliably clear:
- Tomatoes
- Courgettes and cucumbers
- Runner beans and French beans
- Basil
- Sweet corn and pumpkins
- Any seedlings started indoors that haven't been hardened off
Hardening off matters: even after frost risk passes, seedlings kept indoors need a week of gradual outdoor exposure before planting out fully. Bring them out for a few hours each day, increasing the time gradually. Skipping this step shocks the plant even in mild weather.
How to Check the Frost Risk for Your Exact Location
Regional averages are useful, but your garden is specific. These two checks take less than two minutes:
1. Check Met Éireann's forecast for overnight temperatures in your area. A forecast low of 2°C or below with clear skies is frost risk territory, regardless of the date.
2. Watch for clear, calm nights. Frost forms most readily when skies are clear and wind is still. A cloudy, breezy night rarely frosts even at low temperatures. Cloud acts as a blanket; wind mixes warmer air down from above.
If Met Éireann is showing overnight lows above 4°C for the coming week and no frost warnings are active for your county, you're clear to plant out tender seedlings.
Ready to Plant? Here's What to Sow in May
Once you're past the frost risk for your area, May is one of the best sowing months of the Irish year. The soil is warm, the days are long and seeds that go in now will produce harvests before the summer is out.
We've put together a full guide to what to plant in May in Ireland with kids, covering the seven best plants for families, a full May planting calendar and tips for growing without a garden. It's the natural next step once you know you're frost-free.
Growing with Little Sprouts this May
If you'd love to have everything ready to go the moment it's safe to plant out, seeds chosen for the Irish season, a folklore story, nature crafts and a growing guide, all planned and delivered each month. Take a look at the Little Sprouts Garden Box. Everything inside is chosen to work with Ireland's seasonal calendar, so you're always planting at the right time, with the right seeds, without having to figure any of it out yourself.
Ireland Frost Risk May: Common Questions
When is the last frost in Ireland?
For most of Ireland, the last frost typically falls between late April and mid-May. Coastal areas in the south clear earliest, often by the end of April in sheltered spots. Inland areas, the midlands, and the north can see late frosts until the end of May. Higher ground anywhere in Ireland carries frost risk into early June in some years.
Is it safe to plant tomatoes outside in Ireland in May?
Only from late May onwards, and only in sheltered, south-facing spots with overnight temperatures consistently above 4°C. Tomatoes are one of the most frost-sensitive plants you can grow. In Ireland, most gardeners wait until the last week of May at the earliest, and many keep tomatoes under glass or in a polytunnel entirely. If you're planting outdoors, wait until you've had a clear week of mild overnight temperatures.
Can I plant runner beans outside in May in Ireland?
From mid-May in most areas, yes. Runner beans are tender and will be killed by frost, but they can go out once overnight temperatures are reliably above 4°C. In the midlands and north, wait until the last week of May to be safe. Sow two seeds per station, 5cm deep, and give them something to climb.
What can I plant outside right now in Ireland in May?
Throughout May, even before the frost risk fully clears, you can safely sow sunflowers, peas, carrots, beetroot, salad leaves, radishes, kale, spinach, and cornflowers directly outside. These are all hardy enough to tolerate light frosts and will germinate well in May's warming soil. Tender plants like courgettes, tomatoes, basil, and beans should wait until your area's frost risk has passed.