edible gardening
When to plant tomatoes in the UK — complete RHS timing guide
Plant tomatoes outdoors in the UK after the last frost — late May for southern England, early June for Scotland. Sow indoors 6 weeks earlier. Full regional chart.
When to plant tomatoes in the UK — complete RHS timing guide
The single most important decision in growing tomatoes in the UK is when to put them outside. Plant a week too early and a late May frost wipes out a tray of carefully raised seedlings. Plant a week too late and you lose two precious weeks at the back end of a short British summer. This guide is the regional timing chart — by UK region, not USDA zone — plus the soil and weather checks that override the calendar in any given year.
Get your local timing: Add your postcode to Growli and the app ties the tomato planting reminder to your specific area's last-frost date and the live Met Office forecast — not just a generic chart.
The rule
Plant tomatoes outdoors in the UK only after your last expected frost. Tomatoes are tender — they originate in tropical Central America and have no frost tolerance. Anything below 5°C stunts growth; anything below 0°C kills the plant outright.
UK gardeners use the RHS hardiness rating system (H1a-H7) rather than USDA zones — see our UK hardiness ratings primer for what each rating means. For tomatoes, almost the whole of the UK sits in H3 (tender) territory for the plant itself, which is why timing is so unforgiving. Frost-date averages below are statistical — a "last frost of mid-May" means in an average year the last frost is around mid-May, but in any given year you might get a late frost a fortnight later. Track 7-10 day Met Office forecasts before committing seedlings to the ground.
UK timing by region
| UK region | Last frost (avg) | Sow indoors | Plant out (greenhouse) | Plant out (outdoors) |
|---|---|---|---|---|
| Channel Islands, Cornwall, south Devon | Mid-April | Early March | Mid-April | Early to mid-May |
| Southern England (London, Bristol, Brighton, Kent) | Late April | Mid-March | Late April | Mid- to late May |
| Wales (mostly mild but variable) | Late April / early May | Mid-March | Late April | Late May |
| Midlands (Birmingham, Manchester) | Early to mid-May | Late March | Early May | Late May / early June |
| Northern England (Yorkshire, Lake District) | Mid-May | Late March | Mid-May | Early June |
| Scotland (lowlands — Edinburgh, Glasgow) | Mid- to late May | Early April | Late May | Early June |
| Scotland (highlands / islands) | Late May / June | Mid-April | Early June | Mid-June (cover only) |
| Northern Ireland | Late April / early May | Mid-March | Late April | Late May / early June |
These dates are averages. Check the Met Office 10-day forecast for the final two weeks of May before committing seedlings, and look up your specific postcode hardiness rating for a finer estimate.
How to count back from your last-frost date
- Find your last-frost date for your region (chart above) or your specific postcode.
- Subtract 6 weeks for the indoor sowing date.
- Subtract 1 week from the transplant date for the start of harden-off (gradually exposing seedlings to outdoor conditions).
Worked example: southern England, last frost ~28 April, planned outdoor transplant 25 May. Indoor sowing date = 13 April; harden-off start = 18 May; outdoor transplant = 25 May. For a greenhouse transplant move the planting date forward by two to three weeks.
Three signals to check before you plant out
Even when the calendar says go, verify all three before committing:
- Frost-free 10-day forecast — no nights below 5°C projected in the Met Office forecast for your postcode.
- Soil temperature 12-15°C at 10 cm depth — measure with a soil thermometer pushed into the planting bed. Tomatoes refuse to root into cold compost even when the air is warm.
- No big swings ahead — a heatwave the week after transplant is almost as bad as a frost. Aim for a settled 15-22°C window for the first week.
If any of the three is off, wait. A tomato planted in cold soil is stunted for the whole season — the saved fortnight at the start costs you a month of cropping at the end.
Seed-starting timeline
For UK home growers starting from seed (the full setup is in our seed starting indoors UK guide):
| Weeks before transplant | What you do |
|---|---|
| 6 weeks | Sow seeds 5 mm deep into seed-starting compost on a warm windowsill or heated propagator at 21°C |
| 4-5 weeks | Germination complete; remove humidity dome the moment shoots emerge |
| 3-4 weeks | Pot up to 9 cm pots once first true leaves appear |
| 2 weeks | Start feeding with a quarter-strength balanced liquid feed weekly |
| 1 week | Begin harden-off — set seedlings outside in a sheltered shady spot for an hour on day one, building up daily |
| Day 0 | Transplant outdoors or into the unheated greenhouse |
Most UK home growers buy young plants in May from a garden centre, Sarah Raven, Crocus, or a local nursery — for the four to six plants a household actually needs, that is simpler than running a propagator. Starting from seed pays off only if you want unusual varieties or are planting more than ten plants.
What if you missed the window?
If your last-frost date has passed by three or more weeks and you have not yet sown or planted, you have lost about a month of growing time. Recovery options:
- Buy more mature transplants — 30-45 cm plants from Wickes, B&Q, or a specialist nursery skip the early growth phase. Crocus and Sarah Raven post young plants by mail.
- Choose short-season varieties — Glacier and Tumbling Tom ripen in 55-60 days from transplant versus 75-85 for standards. Tumbling Tom is a good rescue choice for late starts because it sets fruit reliably even in cool British summers.
- Use season-extension cover — fleece, cloches, or a polytunnel keep the ground 2-3°C warmer and extend the cropping season by 4-6 weeks at the back end.
In Cornwall, south Devon, the Channel Islands, and the south coast, a second sowing in late June can give a small autumn crop ripened in a cold greenhouse through October.
UK varieties to choose
For UK conditions:
- Gardener's Delight — the classic British cherry; cordon, prolific, reliable on a south-facing patio.
- Sungold F1 — the sweetest orange cherry; cordon, dependable.
- Moneymaker — the workhorse round red; cordon, dependable in unheated greenhouses.
- Shirley F1 — disease-resistant medium-sized red; cordon, long-time greenhouse staple (seed can be harder to source in recent seasons — check Mr Fothergill's or D.T. Brown).
- Crimson Crush F1 — the blight-resistant tomato; if you grow outdoors, start here.
- Tumbling Tom — bush variety bred for hanging baskets and patio pots; outdoor-hardy in southern England.
- Glacier — one of the earliest-maturing varieties available (around 55 days), a useful rescue choice for short or wet British summers.
Tomatoes pair well in your planting calendar with a UK-bred autumn garlic crop — the garlic clears the bed in early July, just as your tomatoes hit full stride.
Skip beefsteak heritage varieties like San Marzano or Costoluto Fiorentino in year one — they need consistent heat the UK rarely provides without a heated greenhouse.
Related articles
- How to grow tomatoes — the UK complete guide — full growing playbook
- Seed starting indoors — UK windowsill and propagator method — start your tomato seeds right
- When to plant garlic in the UK — the autumn companion crop
- UK RHS hardiness ratings explained — find your area's rating and exact last-frost date
Reviewed and updated by the Growli editorial team. For questions about anything here, open Growli and ask — or email hello@getgrowli.app.
Frequently asked questions
When should I plant tomatoes in the UK?
Sow indoors mid-March for southern England, late March for the Midlands, early April for northern England and Scotland. Plant out into an unheated greenhouse from late April (south) to mid-May (north). Plant out outdoors from mid- to late May in the south, early June in northern England and Scotland. Wait until night temperatures stay reliably above 10°C — a late May frost will wipe out your seedlings in one night.
What month do you plant tomatoes outside in the UK?
Late May for the south of England and Wales; early June for the Midlands, northern England, and Scotland; mid-June for the Scottish highlands and the islands (and only under cover there). Earlier than that is a gamble — even in a warm year, one cold snap below 5°C sets the plants back a fortnight. Cornwall, the Channel Islands, and south Devon can plant out from early May in most years.
When should I sow tomato seeds in the UK?
Six weeks before your planned outdoor transplant date. For southern England with a mid-May greenhouse transplant or late-May outdoor transplant, that is mid-March. For northern England and Scotland with a June transplant, sow in early April. Use a heated propagator or a warm south-facing windowsill at 18-21°C — tomato seeds germinate poorly under 16°C.
Can I plant tomatoes outside in April in the UK?
Not safely, except in a very few mild micro-climates (Channel Islands, west Cornwall, south Devon coast). Across the rest of the UK, April nights routinely drop below 5°C and a late frost in the first three weeks of May is normal. Plant out into an unheated greenhouse from late April, or into a polytunnel slightly earlier, but hold outdoor transplants until at least mid-May in the south.
How long does it take to grow tomatoes in the UK from seed?
From sowing to first ripe tomato is roughly 14-16 weeks for an early variety in a greenhouse, 16-20 weeks outdoors. A mid-March indoor sowing gives a first harvest from late July onwards in a greenhouse, mid-August outdoors. The British growing season runs out in October — pick green fruit at the first hint of colour from late August and ripen on a sunny windowsill.
When can I plant tomatoes in a greenhouse in the UK?
Two to three weeks earlier than outdoors. Southern England can plant into an unheated greenhouse from late April; the Midlands from early May; northern England and Scotland from mid- to late May. A heated greenhouse with a minimum 10°C night temperature can plant out in early to mid-April anywhere in the UK. Ventilate aggressively on warm days to discourage blight.
What is the latest I can plant tomatoes in the UK?
Outdoor planting should be complete by the third week of June anywhere south of Edinburgh, otherwise the fruit will not ripen before the autumn cold sets in. Greenhouse planting can extend to early July with short-season varieties (Glacier and Tumbling Tom are the most reliable UK options). After early July, switch to buying mature transplants or wait for next season.
How does Growli decide when to plant tomatoes in my UK postcode?
Add your postcode to Growli and the app ties the tomato planting reminder to your specific last-frost date from Met Office historical data, the live 10-day forecast, your chosen variety's days to maturity, and whether you are growing under cover. The reminder only fires when all conditions check out, not on a generic chart date — so a cold April will push your reminder a fortnight later than the chart says.