Eating Garden

Frost Date Guide

What last spring and first fall frost dates mean, why they are uncertain, and how to use them safely.

A frost date is a planning estimate from past weather. It is not a promise that frost will stop or start on one exact day. Use it to plan, then use the current forecast to protect real plants.

The two dates gardeners use

  • The last spring frost is the approximate end of spring frost risk.
  • The first fall frost is the approximate start of fall frost risk.
  • The time between them is the approximate frost-free growing season.

Why the date can be wrong for your garden

Climate normals describe typical conditions across many years. Your garden may sit higher, lower, nearer water, beside pavement, against a wall, or in a windy opening. These local features create a microclimate that can be warmer or colder than the nearby weather station.

Frost can form near plants even when the official air temperature is slightly above freezing. Clear skies, light wind, and low or sheltered ground can increase the risk.

A freeze and a killing frost are not the same promise

A forecast near 32°F is a clear warning, but plant damage depends on the crop, exposure time, wind, humidity, and the temperature at leaf level. There is no single killing-frost temperature that describes every plant.

Use the spring date

Use the last spring frost to estimate when tender crops may move outside. Then check the crop's cold tolerance, soil temperature, recent weather, and short-range forecast. Cold-tolerant crops may go out earlier. Warm-season crops often need warmer soil and nights.

Use the fall date

Use the first fall frost to judge whether a crop has enough time left to mature and whether tender plants may need protection or harvest. Leave room for slower growth as days cool instead of planting on the last possible date.

When frost is in the forecast

  1. Check which crops are frost-sensitive.
  2. Harvest tender food that is ready.
  3. Cover tender plants before evening when suitable for that crop.
  4. Remove the cover after temperatures rise.
  5. Use the forecast again the next night.

Sources

Crops in this guide

  • Takes some care

    Tomato

    A warm season fruit that almost everyone treats as a vegetable, and the crop most people try first. It needs heat, steady water and something to lean on.

    • Full sun
    • 50 to 85 days
    • 5 gal pot or bigger
    • 24 to 36 in apart
  • Easy

    Basil

    A tender summer herb that grows fast, hates cold nights, and gives more the more often you cut it.

    • Full sun
    • 50 to 75 days
    • 2 gal pot or bigger
    • 6 to 12 in apart
  • Easy

    Lettuce

    A fast, cool weather leaf crop that you can pick from for weeks. It is at its best in spring and autumn, and turns bitter in a hot, dry spell.

    • Part sun
    • 50 to 70 days
    • 1 gal pot or bigger
    • 5 to 12 in apart
  • Takes some care

    Carrot

    A root crop that asks for little except loose, stone free ground and patience while it germinates.

    • Full sun
    • 70 to 80 days
    • 2 to 4 in apart
  • Takes some care

    Strawberry

    A low perennial that fruits for years once established. The first summer is about getting the plants settled; the real crop comes after that.

    • Full sun
    • 300 to 400 days
    • 2 gal pot or bigger
    • 12 to 18 in apart