Last frost

Frost is the gardener's clock. Most of the plants you'll want to grow fall into two camps: hardy ones that shrug off a cold night, and tender ones that a single frost will kill or check badly. The last frost is the average date of the final spring frost where you live, and it's the line that tells you when those tender crops can go outdoors for good.

Why it matters

Tomatoes, courgettes, French and runner beans, pumpkins, sweetcorn and most bedding plants are all tender. Put them out too early and one clear, still night below 0°C can blacken the leaves overnight. Hold them indoors or under cover until the frost risk has passed and they sail away. That's why so much UK growing advice hangs on the phrase "after the last frost" rather than a fixed date — the safe moment genuinely differs from garden to garden.

The matching date in autumn is the first frost — the first cold night that ends the season. The stretch between the last spring frost and the first autumn frost is your frost-free growing window, and it's the practical limit on how long heat-loving crops have to ripen.

Typical UK dates

There's no single national date, because the UK's climate varies enormously over short distances. As a rough guide:

• Southern and south-west England, mild coasts: often early to mid May.
• Much of England and the Midlands: late May is the usual safe point.
• Northern England, Wales, Scotland and any frost pocket: late May into early June, sometimes later.

A frost pocket — a low-lying spot or valley bottom where cold air sinks and settles — can frost a fortnight after the open ground a few streets away, so local knowledge beats any map. The classic gardener's rule of thumb is to wait until the end of May, or even early June in a cold spring, before trusting tender plants to the open garden.

Working with it

Knowing your last-frost date lets you plan backwards. You sow tender crops indoors several weeks ahead, grow them on, then harden them off over a week or two so they're toughened up and ready to plant out the moment the frost risk lifts. A cloche or fleece buys you a little insurance if a late cold snap is forecast after you've planted.

The dates above are averages, not guarantees — a frost can arrive a week or two later than usual. In a cold or unsettled spring, there's no harm in holding off until June; a plant that goes out a fortnight late will quickly catch up, while a frosted one may never recover. When in doubt, wait for the weather, not the calendar.