Plant Hardiness Zone Finder

A hardiness zone tells you one thing and one thing only: how cold your winter usually gets. The USDA divides the country into zones by average annual minimum temperature, and every zone is 10°F wide. Enter a ZIP code or pick a state, and this tool returns your zone along with the plants that reliably survive it.

What the zone number actually means

Zone 6 means the coldest night of an average winter falls between -10°F and 0°F. Zone 7 is 0°F to 10°F, zone 5 is -20°F to -10°F, and so on — each step up is ten degrees milder. When a plant label says “hardy to zone 5”, it means the plant should survive a normal winter anywhere in zone 5 or warmer.

The letters matter too. Zone 6a is the colder half of zone 6 and 6b the milder half, five degrees apart. If you are near the edge of a zone, plant as though you are in the colder one.

What it does not tell you

This is the part that catches people out. The zone says nothing about summer heat, humidity, rainfall, soil, or how long your growing season is. A plant rated for zone 8 will survive winter in both coastal Washington and central Texas — but those are entirely different gardens, and plenty of things that thrive in one will die in the other by August.

It also says nothing about when your last frost falls, which is what actually governs planting dates. For that, use our frost date calculator alongside this one.

Your garden is not your ZIP code

Zones are drawn from weather station data averaged over decades, so they describe a region, not your yard. A spot against a south-facing brick wall can run a full zone warmer than the open lawn thirty feet away. A dip at the bottom of a slope collects cold air and runs colder. City gardens are often a zone milder than the countryside around them.

Container plants are the exception worth remembering: roots in a pot are exposed on all sides and get no insulation from the ground, so treat anything in a container as roughly one zone less hardy than the same plant in a bed. Our guide to plants for balconies and small spaces works through what that means in practice.

Using the zone when you buy

Match or beat your zone number and the plant should overwinter without help. Buy something rated a zone or two warmer and you are gardening on borrowed time — it may last a mild winter or two, then die in a hard one. That can still be a deliberate choice for something you love, as long as you know you are making it. Bulbs are more forgiving than shrubs here; our guide to planting lilies and bulbs covers which ones lift and store rather than take their chances outside.