Planting a Fall Garden: Counting Back from Your First Frost

A fall garden is planted in mid to late summer and harvested as the weather cools. The trick is timing: crops need enough warm days to grow before frost and shorter days slow them down. You find the planting date by counting back from your first fall frost.

Look up your first fall frost, and the earlier date when frost becomes possible, with Frost Dates by ZIP Code.

The count-back formula

For each crop, add up:

1. Days to maturity from the seed packet.
2. About 14 days for shorter, cooler days. Plants grow more slowly in fall than the packet assumes.
3. The harvest period, if you want to keep picking for a while rather than harvest once (often 2 to 3 weeks for beans).

Count that many days back from your first fall frost to get the last date to plant.

For frost-tolerant crops such as kale, spinach, carrots and cabbage, you can count back from a date a few weeks after the first frost, since they keep growing through light frosts. For tender crops such as beans and squash, play it safe and count back from the early frost risk date.

Worked example

Columbus, Ohio has an average first fall frost around October 24, with a 1-in-10 chance of frost by October 13. To grow bush beans that take 55 days:

Step	Days
Days to maturity	55
Fall factor	+ 14
Two weeks of picking	+ 14
Total to count back	83

Counting 83 days back from October 24 gives August 2. Since beans are killed by frost, counting from the safer October 13 date moves it to July 22. Plant between those dates.

Best crops for a fall garden

Crop	Typical days to maturity	Frost tolerance
Radishes	25–30	Hardy
Spinach	40–50	Hardy; survives hard frost
Lettuce	45–60	Light frost
Turnips	40–60	Hardy
Beets	50–60	Light frost
Bush beans	50–60	None; harvest before frost
Kale	50–65	Very hardy; flavor improves after frost
Carrots	60–80	Hardy; sweeter after frost
Broccoli (transplants)	55–70 from transplant	Hardy
Cabbage (transplants)	60–90 from transplant	Hardy

Kale, carrots, cabbage and Brussels sprouts taste sweeter after a few frosts, because the plants convert starch to sugar in the cold.

Garlic: plant in fall, harvest next summer

Garlic works differently. Plant cloves in fall, a few weeks after your first frost and before the ground freezes. They root over winter, grow in spring and are harvested the following summer.

Getting fall crops off to a good start

Starting seeds in midsummer has its own challenges:

• Keep seeds moist. Hot sun dries the soil surface fast. Water daily until seedlings are up, or cover the row with a board or burlap for a few days and lift it as soon as they sprout.
• Shade young plants. Lettuce and spinach germinate poorly in hot soil. Sow them in the shade of taller crops, or start them indoors and transplant.
• Start brassicas indoors or buy transplants. Broccoli and cabbage do better transplanted in late summer than sown directly into hot soil.
• Clear the space. Pull out spent spring crops such as peas, early lettuce and onions, add an inch of compost, and replant.

Stretching the season

A layer of frost cloth or a simple hoop tunnel covered with row cover can add several weeks of harvest in fall. Hardy greens like spinach and kale often keep producing under cover into early winter in many regions.

How much to plant

Fall gardens are usually smaller than spring ones. The Garden Planner gives plant counts per person for lettuce, spinach, kale, carrots and other fall crops; plant about half the spring amounts if you just want fresh greens through autumn.