Gardening in May in Ireland | What To Do

What to Sow in May

May is the last major sowing month for most crops. Direct sow French beans, runner beans, sweetcorn, courgettes, squash, pumpkins and cucumbers outdoors after mid-May once frost risk has passed. Continue successional sowings of lettuce, rocket, radish, beetroot, carrots and spring onions. Sow Florence fennel, chicory, endive and celeriac for autumn harvests. Last chance to sow basil outdoors in a warm, sheltered spot. Wildflower seed mixes can still be sown on prepared ground. Sow quick-growing annuals like sunflowers, nasturtiums and calendula directly for late summer colour.

What to Plant in May

After the last frost risk (mid to late May in most of Ireland), plant out all tender crops: tomatoes, peppers, courgettes, cucumbers, runner beans, sweetcorn and squash. Plant out dahlia tubers and begonia tubers that have been started under cover. Bedding plants can go into borders, containers and hanging baskets. Plant up summer containers with pelargoniums, petunias, lobelia and trailing plants. Hanging baskets can be planted and kept under cover until the last frost. Plant out hardened-off brassicas. Set out celery and celeriac plants.

What to Harvest in May

Asparagus is in full season — cut every two to three days for maximum yield but stop cutting by mid-June to allow the crowns to build up strength. Early potatoes planted on St Patrick's Day should be ready from late May. Broad beans begin cropping. Lettuce, radishes, spring onions, spinach and rocket provide fresh salads. Rhubarb continues strongly. Early peas may be ready in sheltered gardens. Strawberries begin ripening in warm spots and polytunnels. Fresh herbs are abundant — harvest regularly to encourage bushy growth.

Lawn Care in May

May brings rapid lawn growth in Ireland. Mow at least once a week, ideally twice in periods of rapid growth. Lower the cutting height gradually as the season progresses. Apply summer lawn feed for sustained growth and colour. Control weeds with spot treatment or hand-weeding. Water newly sown areas if rainfall is insufficient. This is the last good time to sow new lawns or overseed bare patches before summer drought stress. Treat ant hills by brushing them flat before mowing.

General Garden Tasks for May

Earth up potato plants regularly to prevent tubers being exposed to light. Install supports for runner beans, sweet peas and tall perennials. Tie in clematis and other climbing plants regularly. Pinch out side shoots on cordon tomatoes. Begin daily greenhouse ventilation. Watch for and treat aphids, blackfly on broad beans, and slugs on all vulnerable crops. Feed roses, container plants and hungry vegetables with liquid fertiliser. Harden off all remaining tender plants before planting out. Chelsea chop — cut back late-flowering perennials by half to encourage bushier growth and later flowering.

Ireland-Specific Tips for May

May is one of the most exciting months in Irish gardens, with everything growing vigorously. Average temperatures reach 10-15°C, with occasional warm spells exceeding 20°C. The risk of frost diminishes significantly after mid-May in most areas, though gardens at altitude or in sheltered frost pockets should remain cautious until the end of the month. Ireland's May rainfall is typically moderate, providing useful moisture for newly planted crops. The landscape is spectacular with bluebells, wild garlic and hawthorn blossom. Coastal gardens of Dublin, Wicklow, Cork and Kerry enjoy particularly favourable conditions for tender plants.

Frequently Asked Questions

The last frost date varies significantly across Ireland. Coastal areas of Cork, Kerry, Wexford and Dublin are typically frost-free from late April. The Midlands and inland areas remain at risk until mid-May, and elevated or sheltered frost pockets can experience frost into late May. As a general rule, mid-May is considered safe for planting out tender crops in most of Ireland. However, it is always wise to check the weather forecast and have horticultural fleece ready to protect plants if an unexpected late frost is forecast.

Wait until at least mid to late May to plant tomatoes outdoors in Ireland, and only then in sheltered, south-facing positions. Tomatoes need consistent warmth and perform better in greenhouses, polytunnels or against warm south-facing walls in Irish conditions. If planting outdoors, choose bush varieties like Tumbler, Maskotka or Red Alert which ripen more reliably in Ireland's relatively short, cool summers. Use black plastic mulch to warm the soil and cloche protection in cooler areas.

Slugs become very active in May as temperatures rise and rain keeps conditions damp. Use a combination of methods for best control: apply organic slug pellets around vulnerable plants, set up beer traps sunk into the soil, create barriers of copper tape around containers, and encourage natural predators like hedgehogs, frogs and thrushes. Evening patrols with a torch are effective — collect and relocate slugs to waste ground. Nematode biological controls can be watered onto the soil when temperatures are above 5°C. Protect seedlings with cut plastic bottle cloches.

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What To Do In Your Irish Garden In May