How to Use Your Last Frost Date Without Getting Caught by a Late Cold Snap

Seven-day forecast strip with one freezing night and a covered garden bed


Every gardening guide tells you to plant after the last frost date, but that date is only an average. In roughly half of years the final frost of spring arrives later than the number printed on the chart. The practical question is not what is my date but how much risk am I willing to take with each crop.

Sort your crops into three risk groups

Hardy crops such as peas, spinach, kale, onions and radishes shrug off light frost, so they can go out weeks before your date. Half-hardy crops such as lettuce, carrots, beets and potatoes are usually fine a week or two early if the soil is workable. Tender crops such as tomatoes, peppers, cucumbers, squash and basil should wait until the date has passed and nights are reliably mild.

Check the forecast, not just the calendar

Look at the overnight low for the next seven days before you set out tender plants. A night forecast near freezing is the signal to hold off or cover. Cold air settles in low spots, so a corner of the yard can frost while the rest does not.

Keep a cheap safety net

A roll of floating row cover, a few old bed sheets or upturned buckets will protect plants through a one-off cold night. Put the cover on in the evening, anchor the edges, and take it off the next morning once it warms up.

Write down your own dates

The most useful number is the one from your own garden. Note the date of the last frost you actually saw each spring. After two or three seasons you will know whether your yard runs earlier or later than the regional average.

If you want the sowing and transplanting dates worked out for you, the free planting calendar builds a schedule from your ZIP code or your own frost dates, and the frost dates guide explains how the numbers are calculated.

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