Northern Ireland Gardening Guide UK

Northern Ireland has a mild, wet maritime climate with fewer frost nights a year than England as a whole, but cool springs mean the RHS still puts planting out of tender crops in early June.

Frost and rainfall figures are Met Office 1991–2020 averages; planting-out times are the RHS’s. Growing advice verified against RHS guidance.

Frost and planting-out times

How many nights a month have an air frost, on Met Office 1991–2020 averages, with yearly rainfall. The RHS’s typical first safe time to plant out tender crops here is early June; the last spring air frost usually comes two to four weeks before that, and exposed or high sites run one to three weeks later.

Month by month

The main sowings and plantings each month from our UK month guides (which follow the RHS monthly jobs). Expect tender crops to go out at the time shown above, not earlier.

• January: Plant outdoors: Bare-root fruit
• February: Sow indoors: Tomatoes; Sow indoors: Chillies, cucumbers, aubergines; Sow in guttering in the greenhouse: Peas
• March: Sow outdoors: Broad beans, peas, parsnips, turnips, maincrop onions, brassicas, kale, corn salad, land cress; Sow outdoors: Carrots, beetroot, lettuce, radish, spinach, leeks, chard, kohl rabi; Plant: Onion , shallot and garlic sets
• April: Plant: Second early potatoes; Plant: Maincrop potatoes; Sow outdoors: Carrots, beetroot, lettuce, peas, leeks, radish, chard, turnips, kohl rabi, spring onions, perpetual spinach
• May: Sow outdoors: French beans, runner beans, squash, cucumbers, pumpkins; Sow outdoors in blocks: Sweetcorn; Plant out: Tomatoes, courgettes, pumpkins
• June: Plant out: Tomatoes, courgettes, sweet peppers, ridge cucumbers, winter brassicas; Sow outdoors: French and runner beans, peas, squash, outdoor cucumbers; Sow outdoors in a block: Sweetcorn
• July: Sow outdoors: Spring cabbage, turnips, pak choi, Chinese cabbage, tatsoi, mizuna, chicory, fennel , winter salads; Sow outdoors: Carrots; Sow outdoors: French beans , runner beans
• August: Sow: Spring cabbage, turnips, mizuna, mibuna, Chinese cabbage, pak choi, overwintering onions; Sow: Radish, rocket , lettuce, chicory, sorrel, fennel; Sow: Spinach , corn salad, chard , kohl rabi
• September: Plant: Overwintering onion sets; Plant: Garlic; Sow: Spinach, winter lettuce, rocket , salad leaves
• October: Plant cloves outdoors: Garlic; Plant sets outdoors: Onion sets (overwintering); Sow where they will grow: Broad beans
• November: Plant cloves outdoors, or in modules in a cold frame: Garlic; Sow outside or under cloches; in cold areas, sow in pots under unheated glass: Broad beans; Sow to overwinter, in covered containers: First early peas
• December: Plant cloves: Garlic; Plant sets with the tip just showing: Shallots; Plant: Bare-root fruit trees and bushes

Crop guides to start with

Guides for crops that appear throughout the UK month guides:

• Potatoes
• Leeks
• Cabbage
• Kale
• Carrots
• Onions
• Garlic
• Broad beans
• Peas
• Beetroot
• Lettuce
• Runner beans
• Courgettes
• Brussels sprouts
• Parsnips

Weather notes

Northern Ireland averages about 41 air-frost nights a year, against about 45 for England as a whole (Met Office 1991–2020), but frosts still occur in May. Plant tender crops out in early June, after hardening them off gradually.

Back to regional gardening in the UK, or see the UK vegetable planting calendar and the sowing calendar by region (269 crops).

References

• Met Office: UK location-specific long-term averages, 1991–2020
• RHS: When to plant out tender plants – avoiding late frosts
• University of Illinois Extension: Starting a garden: hardening off indoor seedlings
• University of New Hampshire Extension: Starting plants from seed (fact sheet)
• West Virginia University Extension: Vegetable transplant production

Figures in the tables are the official averages named above. Every other statement is supported by at least three of these sources. The month-by-month notes summarise our own month guides, each of which lists its sources. All sources were checked on 24 October 2026.

Last reviewed: 24 October 2026