Almost every seed packet and plant label dates itself from the last frost — “sow six weeks before the last frost”, “plant out after all danger of frost has passed”. This calculator gives you the two dates those instructions are counting from: the average last frost in spring and the average first frost in autumn for your area.
Enter a ZIP code, or pick a state if you only need a rough window.
❄️ Frost Date Calculator
Find last spring & first fall frost dates
📋 Detailed Information
🌿 When to Plant
- Cold-hardy crops: 4-6 weeks before last frost
- Tender vegetables: 2 weeks after last frost
- Half-hardy plants: 1 week before last frost
What these dates actually mean
They are averages, not deadlines. A last frost date of 15 April means roughly half the years have had a frost after that date. If you plant tender crops the day the calculator gives you, you are taking a coin-flip on the weather; wait a fortnight and the odds move firmly in your favour.
It is also worth knowing that your own garden is not the same as your ZIP code. A low-lying bed at the bottom of a slope collects cold air and frosts days later than a bed against a south-facing wall.
Planting around the last frost
Hardy things — onions, peas, most spring bulbs — go in well before the date. Tender things — tomatoes, basil, squash, dahlias — go in well after it. If you have raised seedlings indoors, harden them off over a week or so before they go out, giving them a few hours outside at first and building up; moving them straight from a windowsill to an exposed bed sets them back badly even without a frost.
Our guide to spring plants for balconies and small spaces is a good place to start if you are working with containers, where roots are far more exposed to cold than they are in the ground.
When a late frost is forecast
Water the soil in the afternoon — damp soil holds and releases more heat overnight than dry soil. Cover vulnerable plants with fleece, an old sheet or an upturned pot before dusk, so you trap the day’s warmth rather than sealing in cold air, and take the covers off in the morning. Containers can simply be moved against the house wall for the night.
Bulbs are more forgiving than they look. If you are planting for spring colour, our guide to planting lilies and bulbs covers the depths and timings that matter more than the frost date does.