Frost Dates & Succession Planting: A Beginner's Guide to Timing Your Vegetable Garden
Two numbers decide almost everything about when to plant: your average last spring frost date and your average first fall frost date. Nearly every seed packet's "4 weeks before frost" or "2 weeks after frost" instruction is counted from one of those two dates — not from a fixed calendar date that works the same everywhere.
Once your timing is set, pairing crops in the same bed is the next question — see our companion planting guide for which pairings are well-established and which are closer to folklore.
Why "weeks before/after frost" is the only timing that travels
Your last spring frost and first fall frost dates aren't fixed calendar days — they're statistical averages specific to your location, typically defined as the date with roughly a 10% chance of frost still occurring after it (in spring) or already occurring before it (in fall), per Purdue University Extension. A local Cooperative Extension office or a nearby long-running weather station's climate records are the most reliable way to find your own two dates; once you have them, every chart below applies regardless of whether you garden in a short-season or long-season climate.
Spring planting: counted backward and forward from your last frost
Purdue Extension's planting-date guidance (HO-186-W) groups vegetables into four timing bands based on frost tolerance, not by calendar date:
| Timing (relative to last spring frost) | Frost tolerance | Crops |
|---|---|---|
| 4–6 weeks before | Hardy — tolerates a hard frost | Asparagus, broccoli, Brussels sprouts, cabbage, collards, horseradish, kale, kohlrabi, leek, mustard, onion, peas, potato, radish, rhubarb, spinach, turnip |
| 2–4 weeks before | Semi-hardy — tolerates a light frost | Beet, carrot, cauliflower, celery, chard, Chinese cabbage, lettuce, mustard, parsnip |
| At the frost date itself | Tender — damaged by frost (needs air ≥50°F) | Bean, sweet corn, tomato |
| At least 2 weeks after | Very tender — damaged even by a light frost (needs air 60–65°F) | Cucumber, eggplant, melon, okra, pepper, pumpkin, squash, sweet potato |
The pattern underneath the chart: the hardier the crop, the earlier it goes in relative to your frost date, and warm-season crops aren't just "fine after frost" — the very tender group specifically needs the soil and air to warm well past the frost line, not just past freezing.
Fall planting counts backward from the first fall frost instead
The same extension guidance flips the reference point for a fall crop: cool-season vegetables go in at least 4–8 weeks before your first fall frost — beet, broccoli, Brussels sprouts (transplant by midsummer), cabbage, collards, green onion, kale, kohlrabi, lettuce, mustard greens, radish, spinach, and turnip all fit this window. One practical catch: anything sown after September 1 takes longer to mature as daylight shortens, so a fast-maturing variety matters more for a late fall planting than it does in spring.
Succession planting: turning one frost-date chart into a season-long harvest
A single planting date gets you one harvest window. University of Missouri Extension's succession-planting guidance splits crops into two different approaches depending on how they produce:
- Resow roughly every 2 weeks, all season: radish, carrot, beet, kohlrabi, sweet corn, and turnip. These are harvested once per planting (a root crop, or an ear of corn), so a fresh, modest sowing every couple of weeks is what keeps a harvest coming rather than one big glut.
- Add a new row every ~14 days of crops that produce heavily, then taper off: cucumber, bush beans, broccoli, cabbage, and lettuce, among others. Yields on these typically fall sharply about two weeks into peak production — staggering new rows in, and removing spent ones, keeps supply level instead of feast-then-famine.
University of Maryland Extension's version of this is called relay planting: green beans sown at two-week intervals — for example, a mid-May sowing followed by a mid-July sowing — rather than one large planting that all comes in and finishes at once.
The underlying reason succession planting works as well as it does isn't just about spacing out the harvest — it also spreads your risk. If one week's sowing hits a cold spell or germinates poorly, the sowings two weeks on either side of it usually don't share the same bad luck.
Putting it together
In practice: find your two frost dates once, use the weeks-before/after chart to set your first planting date for each crop, and then layer succession sowings on top for anything in the "resow" or "new row" groups above. The chart tells you when to start; succession planting is what keeps the bed producing after that first planting is done.
A system built around your own frost dates, not a generic calendar
This article covers the reasoning; the Homestead Garden Master Planner turns it into a personal worksheet plus a full Master Sowing & Succession Calendar — enter your own frost dates once, and every timing in the planner follows from them. For a simpler single-season tracker, see the Garden & Seed Starting Planner, or plan the whole year ahead with the dated 2027 Homestead Planner.
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