Planning a Fall Vegetable Garden: Count Back From Your First Frost
A spring garden is planned forward from the last frost. A fall garden is planned backward from the first one. The question is no longer "how early can I start?" but "what is the last day I can sow this and still harvest before the cold shuts it down?" Get that date right and late summer becomes a second planting season, often a better one for lettuce, carrots and broccoli, which prefer cool weather.
The Planting Calendar is built around your spring frost date, but it carries the two numbers a fall plan needs: each crop's days to maturity and the "days to spare" before your first fall frost. This guide shows how to use them to count back, with worked dates for two example gardens.
Start with an honest first frost date
Get your average first fall frost date from your local extension service or national weather service. Remember that it is an average: on that date frost is roughly as likely as not, and a cold pocket at the bottom of a slope can freeze earlier than the official figure. Frost dates also shift from year to year. That uncertainty is why the fall plan below includes an allowance rather than counting right up to the date.
If you run a crop through the Planting Calendar and leave the first fall frost blank, it assumes a frost 200 days after your last spring frost and labels the season "(assumed)". For fall planning that assumption is exactly the number you should not trust. Type in your own date.
The counting rule
For each crop: latest sowing date = first fall frost minus days to maturity minus an allowance.
The allowance covers two things. First, crops sown in late summer mature into shortening, cooling days and grow more slowly than the packet promises, so many gardeners add about two weeks for that alone. Second, you want to harvest over a few weeks, not on a single day right before a freeze. We show the bare date and the date with a 14-day allowance; for frost-tender crops, treat the 14-day date as the real deadline.
Worked dates: first frost October 15, 2027
These use the Planting Calendar's own days to maturity for each crop and an example first frost of October 15, 2027.
| Crop | Days to maturity | Latest sowing (no allowance) | Latest sowing (14-day allowance) |
|---|---|---|---|
| Lettuce | 45 | August 31 | August 17 |
| Beans | 55 | August 21 | August 7 |
| Cucumbers | 60 | August 16 | August 2 |
| Carrots | 70 | August 6 | July 23 |
| Broccoli (transplant) | 70 from transplant | August 6 | July 23 |
| Squash | 90 | July 17 | July 3 |
Worked dates: first frost October 1, 2027
Two weeks less season moves every date two weeks earlier. That sounds obvious, but it is the difference between a fall carrot crop and a row of finger-sized roots.
| Crop | Latest sowing (no allowance) | Latest sowing (14-day allowance) |
|---|---|---|
| Lettuce | August 17 | August 3 |
| Beans | August 7 | July 24 |
| Cucumbers | August 2 | July 19 |
| Carrots | July 23 | July 9 |
| Broccoli (transplant) | July 23 | July 9 |
| Squash | July 3 | June 19 |
Hardy crops and tender crops need different deadlines
Frost-tender: beans, cucumbers, squash
These die at the first real frost, and they slow down in the cool nights before it. The harvest has to be finished, not just started, by the frost date. Use the 14-day column, and if your garden sits in a frost pocket, go earlier still. Squash at 90 days is really a late-spring or early-summer sowing in most gardens; by midsummer it is usually too late for a fall crop.
Frost-tolerant: lettuce, carrots, broccoli
These handle light frost, and carrots and broccoli often taste sweeter after a cool spell. For them the frost date is less of a wall. You can sow nearer the bare date and stretch the harvest with frost cloth, a cold frame or a low tunnel. Lettuce is the most delicate of the three: a hard freeze will damage it, so cover it on cold nights.
Fall broccoli: start the seedlings in early summer
Broccoli's 70 days in the calendar run from transplanting, and the calendar gives it six weeks as a seedling before that. With an October 15 frost and the 14-day allowance, transplants need to be in the ground by July 23, which means starting seeds around June 11. That surprises people: fall broccoli is a June job. Start seedlings in a bright, sheltered spot outdoors or under lights indoors, and keep them watered through the heat.
If you sow broccoli direct instead, the calendar adds the six seedling weeks to its harvest date as a rule of thumb. You can see this in a spring run: direct-sown on April 6, 2027 with an April 20 last frost, broccoli is expected on July 27, against June 15 for transplants set out on the same date. The same 42-day penalty applies in fall, so direct-sown fall broccoli needs to go in about six weeks before the transplant deadline.
Use the spring run to see how much season you have
Run a crop through the Planting Calendar with your real spring and fall frost dates and read "Days to Spare Before First Frost". With an example April 20 last frost and October 15 first frost, a May 4 sowing of beans is ready on June 28 with 109 days to spare, and an April 6 sowing of carrots is ready on June 15 with 122 days to spare. A margin that large tells you the bed will be empty for most of the summer unless you plan a second crop. Our guide to succession planting lettuce and beans covers filling that gap in two-week steps.
Getting summer sowings to come up
Fall crops are sown into the hottest, driest weeks of the year, which is the opposite of spring sowing conditions. A few habits make the difference:
- Water the seed row daily until seedlings emerge. A dry crust is the main reason midsummer carrot and lettuce sowings fail. A board or a strip of burlap laid over a carrot row keeps it damp; lift it as soon as the first seedlings show.
- Sow lettuce in the evening and give it shade. Lettuce germinates poorly in hot soil. A shade cloth or the shadow of a taller crop helps.
- Clear and refresh the bed. Pull the spent spring crop, add an inch or two of compost and rake level. Our guide on how much compost to add to a garden bed works out the volume.
- Plan water for the hottest weeks. Young fall crops need steady moisture; see how much water a vegetable garden needs each week.
- Watch for pests that peak in late summer. Cabbage worms and flea beetles love young brassicas. Row covers put on at sowing or transplanting are the simplest protection.
What the calendar does not do for fall
- It does not count back for you. The calendar plans from the spring frost date. The fall deadlines above are its days to maturity subtracted from your first frost date; it has no "fall sowing" mode.
- It does not add a fall allowance. Its harvest dates assume the crop grows at its packet speed. Late-season crops usually grow slower.
- It knows one variety per crop. A 50-day carrot and a 75-day carrot both read as 70 days. Use your packet's number.
- It has no frost-hardiness setting. Its frost warning treats every crop the same; you decide which crops can ride out a light frost under cover.
- It does not know your microclimate or this year's weather. Watch the forecast from late September and have covers ready.
A fall planning checklist
- Write down your average first fall frost date from a local source.
- List the crops you want and their days to maturity from your seed packets.
- Subtract days to maturity and a 14-day allowance from the frost date for each.
- Circle the tender crops; their date is a hard deadline.
- Put the broccoli and cabbage seed-starting dates on the calendar in early summer.
- Keep frost cloth or a cold frame ready for the hardy crops in October.