The One-Big-Planting Mistake
You direct-sow a whole packet of lettuce in May. Four weeks later you have 40 heads ready at once — more than you can eat in a week. You give away bags of salad, the rest bolts in the June heat, and by July you have nothing. That is the most common kitchen-garden mistake, and it has nothing to do with your soil or your timing. It is a math problem.
Succession planting solves it by spreading one season's worth of seed across multiple smaller sowings. Instead of 40 heads in week eight, you get 8 heads in week eight, 8 more in week ten, and so on until frost. You never have too much at once, and you never go without.
Work Backward From Fall Frost, Not Forward From Spring
Most gardeners plan forward: they start with today and ask "when can I plant next?" The problem is that this ignores the hard stop at the end of the season. A bush bean planted too late will still be developing pods when the first frost kills it.
The right approach is to anchor your schedule to the last viable sow date, then fill backward toward spring. The formula:
last_viable_sowing = fall_frost − (days_to_maturity + 14)
That date is fixed. Work backward from it in equal intervals — whatever cadence you want, typically one to three weeks — and you have your complete schedule. Every date in the calculator is generated exactly this way.
Why Fall Crops Need the +14 Buffer
Every seed packet lists days to maturity. That number was measured in summer, when days are long. Day length — specifically the ratio of light to dark — governs how fast plants progress through their growth stages. As days shorten after the solstice, the same variety that matures in 50 days in June will take 60–64 days when sown in August.
This is a photoperiod effect, not a temperature effect. You cannot compensate for it with a row cover or extra fertilizer. If you ignore it, your last planting of the season will still be half-grown when frost arrives.
The calculator adds 14 days as a conservative buffer — it gives you some margin if your local fall runs slightly warmer or if you are growing a faster-than-average variety. If you know your specific variety's fall performance, you can trim that buffer, but 14 days rarely leads you wrong.
Frost-Tolerant Crops Get a Grace Window
Spinach, arugula, kale, radish, beets, and carrots can survive light frosts (28–32°F) and often improve in flavor after cold exposure. For these crops the calculator extends the planting window by 7 additional days past the standard last viable date. Those dates appear in the schedule labeled with the grace window — use them, but keep an eye on the forecast.
Which Crops Succession Well and Which Don't
Not every crop rewards succession planting. Here is the split:
Worth succession planting
Fast-maturing crops that are harvested all at once (radish, bush beans, cilantro) or over a short window (lettuce, arugula): sow every 1–3 weeks for a steady supply. Beets and carrots can go every 3 weeks since they store in the ground for a few weeks once mature.
One planting is enough
Tomatoes, peppers, eggplant, cucumbers, and winter squash are indeterminate or produce over a long period from a single planting. Starting a second tomato plant six weeks after the first adds almost nothing — both will produce through the same window. Spend the bed space on a succession crop instead.
Corn is a special case
Sweet corn is harvested once per plant, so succession planting does extend your harvest window. But corn requires a block planting of at least 16 plants for wind pollination. Stagger two 16-plant blocks by 14 days, not two 8-plant rows — under-pollinated corn produces sparse, misshapen ears.
Pairing Successions With Bed Planning
The full system works like this: divide your bed into equal sections, one per sowing. Each section gets replanted the moment the previous batch is harvested. As soon as you pull a spent lettuce row, the next transplants go in — no day of empty bed space.
To make this work in practice, start transplants indoors about two weeks before each outdoor slot. That way you are dropping in established seedlings rather than waiting 10 days for direct-sown seed to emerge. Two weeks of indoor time translates directly to two more weeks of productive bed time per cycle.
Use the Raised Bed Soil Calculator to confirm your bed is deep enough — lettuce and radish need only 6 inches, but carrots and beets need 12. Getting the depth wrong on a succession bed wastes an entire season of cycling.