Interactive Planting Zone Finder UK
Find your UK hardiness zone by postcode, by clicking the map, or by picking your zone. Computed from 30 years of Met Office climate data.
The United States has an official hardiness zone map. The UK does not: the RHS rates plants with its H1 to H7 scale, but no official map zones British places. So Growit computed one. We took 30 years of Met Office climate data, averaged the coldest night of every year at every point on a 5 km grid, and classified the result into the same hardiness bands the USDA uses, in Celsius. Find yours three ways: enter your postcode, click the map, or pick your zone from the list.
A zone is not a planting date. It tells you which plants survive your coldest nights, and nothing about when your last frost falls. Once you know your zone, use the zone cards below to see which crops suit it, and the Seasonal Garden Calendar to plan the year.
Your zone
- –average annual extreme minimum temperature
- –where this zone occurs
- –example crops
2. Or click the map
Click anywhere in Great Britain or Northern Ireland to see the zone at that exact spot. The boundaries are simplified for the web, so treat a click near a boundary as approximate, and use the postcode lookup for a general answer.
Map: hardiness zones computed by Growit from HadUK-Grid climate data (1991 to 2020). This is not an official map. Base map © OpenStreetMap contributors. Click a coloured area to set your zone.
How this is worked out
A hardiness zone is defined by one number: the average annual extreme minimum temperature, meaning the coldest night of the year, averaged over 30 years. Each whole zone spans 5.6 °C, and each splits into two half-zones of 2.8 °C. Zone 9 covers -6.7 to -1.1 °C; 9a is -6.7 to -3.9 °C and 9b is -3.9 to -1.1 °C. These are exactly the USDA bands, converted to Celsius.
Assumptions:
- The climate source is HadUK-Grid, the Met Office gridded climate dataset built from the UK weather station network, on a 5 km grid. The grid is interpolated between stations, which smooths the coldest extremes, so every zone on this page is approximate.
- The postcode lookup assigns each district the zone at the centre point of its postcodes (centroids from the ONS Postcode Directory). A rural district can span two zones; the result is the centre point’s zone. All 2,943 districts have a zone.
- A map click and a postcode lookup can disagree near a boundary. A district covers an area; a click is one point. Trust the click for a specific garden bed.
- The data covers Great Britain and Northern Ireland. The Channel Islands and the Isle of Man are outside the HadUK-Grid extent, so the map gives no reading there.
Three worked examples
1. Penzance, postcode TR18. The lookup returns Zone 9b, minimum -3.9 to -1.1 °C. Cornwall’s mild coast lets gardeners overwinter tender plants that would die in most of the country, though a hard winter still bites.
2. A click on Fort William, Scotland. Clicking the Highland town returns Zone 8b, minimum -9.4 to -6.7 °C. Hardy vegetables, currants, and apples thrive; tender crops need the warmest sheltered wall.
3. Picking Zone 10 by hand. Choose Zone 10 from the list and the page shows a minimum of -1.1 to 4.4 °C. In this dataset only the Isles of Scilly reach it, at 10a: frost is a rare visitor, and subtropical plants grow outdoors all year.
UK hardiness zones at a glance
Four zones cover the country in the climate data, from the Highland cold of Zone 7 to the frost-light Isles of Scilly at Zone 10. Most gardeners will land in Zone 8 or 9. Minimum temperatures are the band definitions; the descriptions are typical, not promises. Click “Show this zone” on any card to load it into the result above.
Zone 7
Minimum temperature: -17.8 to -12.2 °C
Where it occurs: Almost nowhere at garden level in this dataset: one high pocket in the Scottish Highlands reaches the colder half of this band (7b). Treat Zone 7 as the extreme edge of the map, not a typical district.
Example crops: Garlic, broad beans, kale, rhubarb, and the highest-chill apples and pears.
Zone 8
Minimum temperature: -12.2 to -6.7 °C
Where it occurs: Uplands and high ground: the Cairngorms and Highland glens (8a), the Pennines, the Welsh mountains, and Fort William at 8b, plus cold inland frost pockets.
Example crops: Garlic, broad beans, peas, kale, parsnips, apples, pears, and currants. Tender crops need a sheltered spot and frost cover.
Zone 9
Minimum temperature: -6.7 to -1.1 °C
Where it occurs: Most of lowland Great Britain and Northern Ireland. London, Edinburgh, Cardiff, Belfast, Manchester, and most towns and cities sit in this band; the mildest coasts, Cornwall and the Channel coast, reach 9b.
Example crops: Almost all hardy vegetables and fruit. Citrus and other tender plants still need winter protection away from the mildest coasts.
Zone 10
Minimum temperature: -1.1 to 4.4 °C
Where it occurs: The mildest pocket in the country in this dataset: the Isles of Scilly (postcode districts TR21 to TR25) at 10a. Nowhere on the mainland reaches Zone 10.
Example crops: Subtropical planting outdoors: palms, bananas in shelter, and tender perennials that would need a greenhouse almost everywhere else in the UK.
Common zone mistakes
- Treating these zones as an official map. No UK body publishes a USDA-style zone map. The zones here are USDA-style bands computed from Met Office climate data, built so gardeners can use the zone numbers printed on imported plant labels and seed packets.
- Mixing up zones and RHS ratings. An RHS rating like H5 rates a plant; a zone here rates a place. The numbers do not convert into each other. A plant labelled hardy to USDA Zone 8, though, can be compared directly with this map, because the bands are the same.
- Comparing zone numbers between systems. A Canadian Zone 6 is not a British Zone 6: Canada uses its own index built from temperature, rainfall, snow, and wind. Zone numbers only compare inside one system.
- Trusting a postcode for a whole district. A Highland district can cover glens and coast at once. Its zone comes from its centre point. If your garden sits near a coast or high ground, click your exact spot on the map as well.
- Ignoring microclimates. A frost hollow at the bottom of a slope, a south-facing brick wall, or a city courtyard can shift your real minimum by a full half-zone. The map cannot see your garden’s slope.
- Assuming a zone means planting time. Zone 9 covers both London and Belfast, whose springs do not arrive on the same week. The zone rates cold survival only; your sowing calendar still follows your local frost dates.
What to do next
Once you know your zone, plan the year with it: the Seasonal Garden Calendar turns your zone into a month-by-month task list, and the frost calculators in the sidebar help you time tender crops. If you also grow for the kitchen, the UK Vegetable Prices page shows what your harvest is worth at wholesale.
Putting the result to work
A zone is only useful if it changes what you buy and when you plant. Use it three ways. First, filter plant purchases: if a label says hardy to Zone 9 and you are in Zone 8, either skip it or plan winter protection before you pay. Second, set expectations for perennials: a plant at the warm edge of its range may sulk through a wet winter even though the temperature never troubles it, because these zones measure cold only, not rainfall or waterlogging. Third, match crops to the band: high-chill fruit like apples and cherries earn their keep in Zones 7 and 8, while tender Mediterranean herbs overwinter reliably only in 9b and above.
And remember the map’s limits. Zones are drawn from 30 years of station data, and your garden has its own weather. Keep a simple note of your own coldest nights and first frosts each year. After two or three seasons you will know your garden better than any map does.
How to find your UK planting zone in 3 steps
- Enter your full postcode (or just the district, for example SW1A) and press Find my zone. Or click any spot on the map, or pick your zone from the list.
- Read your result: the half-zone (for example 9b) and its minimum temperature range in degrees Celsius.
- Use the zone card below to see where that zone occurs and which crops suit it, then plan your planting around your local frost dates.
Zone = average annual extreme minimum temperature, 1991 to 2020 (HadUK-Grid climate data). Whole zone = 5.6 °C; half-zone = 2.8 °C.
What is my planting zone in the UK?
The UK has no official USDA-style zone map, so Growit computed one. We took 30 years of UK climate data (1991 to 2020) from HadUK-Grid, the Met Office gridded dataset, averaged the coldest night of each year at every point on a 5 km grid, and classified the result into the same hardiness bands the USDA uses. Enter your postcode above, click the map, or pick your zone from the list.
How is this different from RHS hardiness ratings?
The RHS ratings (H1 to H7) describe a plant: how much cold that plant can survive. A zone on this page describes a place: how cold that place gets in an average winter. Use both together: find your zone here, then check a plant’s H rating or its USDA zone range on the label. This page is a Growit tool, not an official RHS product, and the two systems are not interchangeable numbers.
Why do the zones run from 7b to 10a?
Hardiness bands are defined by the average annual extreme minimum temperature. Each whole zone spans 5.6 degrees Celsius, and each splits into two half-zones, a and b. The British climate lands in the middle of the scale: the coldest Highland pocket is Zone 7b, most lowland towns and cities are Zone 9a, the mildest coasts reach 9b, and the Isles of Scilly reach 10a.
Why does my postcode give a different zone than the map click?
A postcode district covers an area, and its zone here comes from the centre point of that district. A map click is one exact spot. Central London shows the difference: the SW1A district (Westminster) returns Zone 9a from its centre point, while a click a few streets east in the City returns Zone 9b. Trust the click for a specific garden bed, and the postcode for a general answer.
How accurate is this map?
Treat it as good guidance, not survey data. The climate grid is interpolated between weather stations, which smooths out the coldest extremes, and the map boundaries were simplified for the web, so they are approximate to about 2 to 5 km. A frost hollow, a slope, or a city heat island can shift your real garden by half a zone either way.
Zone data computed by growit.wiki/ from HadUK-Grid v1.3.2 climate data, Met Office, metoffice.gov.uk, licensed under the Open Government Licence v3.0: average annual extreme minimum temperature, 1991 to 2020, classified into USDA-style bands. Postcode district centroids: ONS Postcode Directory, Office for National Statistics; contains OS data © Crown copyright and database right, and Royal Mail data © Royal Mail copyright and database right. Map polygons simplified for web use. This is not an official Met Office or RHS map. Base map © OpenStreetMap contributors. Results are estimates for planning.
