Harvest Date Calculator
Add days to maturity to a planting date for a calendar harvest date, with the margin left before first fall frost.
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Succession Planting Calculator
Six staggered sow-and-harvest date pairs from a start date and interval, turning one glut into a season of steady harvests.
Succession Planting Calculator
Chlorova · updated for 2026
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Click “Calculate” to see your results.
The engine always prints six batches, so the last sowings of a long-maturity crop can project harvests past your first frost; check those dates against the frost calendar rather than assuming the season stretches to cover them. Maturity days are packet ideals, and hot weather speeds radish and lettuce while it delays germination in carrots, so real stagger drifts a few days per batch. Succession works best with a modest patch per batch rather than the whole bed each time, because six full-bed sowings simply recreate the glut with extra steps.
The difference between a garden that feeds you for three weeks and one that feeds you for three months is not more space, it is time, sliced into sowings. Succession planting staggers a fast crop across the season so every batch matures well after the last one finishes. This calculator lays out six sow-and-harvest date pairs from your first sowing date and interval, turning a good gardening habit into an actual calendar you can pin on the potting bench and follow all summer.
Laying Out the Stagger
- Choose a fast-maturing crop to relay, radish through carrot.
- Enter the exact calendar date of your very first sowing.
- Set the interval days between sowings, fortnights suit salads.
- Read the six sow-batch dates printed down the results panel.
- Check each paired harvest date, staggered one maturity apart.
- Use the harvest-window spread to see how long picking lasts.
- Verify against the frost calendar that the final harvest lands safe.
- Divide the bed into six small strips, one reserved per batch.
- Mark a reminder for every sow date the plan generates.
Six of the Same Addition
Every sow date is the first sowing plus a multiple of the interval, batch six sitting at five intervals out, and each harvest adds the crop's maturity days to its own batch. The arithmetic is deliberately repetitive, because that is exactly what succession is: the same small sowing, again and again, until the calendar fills with staggered harvests instead of one week of chaos.
The two summary lines size the plan: the harvest spread is five intervals, the length of time the table keeps producing once it starts, while first-sow-to-last-harvest adds a full maturity count and shows the whole season footprint. Radish at a fortnight gives a seventy-day stagger on a thirty-day crop, which is a summer of salads from six short rows.
Worked Example: Radishes Every Fortnight
- Radishes mature in about thirty days, the fastest relay here.
- You set the first sowing for May 1 with a fourteen-day gap.
- The batches then land May 15, May 29 and June 12.
- Then June 26 arrives, and the final sowing on July 10.
- Each harvest date sits exactly thirty days behind its own sowing.
- The first tender radishes are on the plate by May 31.
- The last batch closes the whole sequence on August 9.
- So the plan buys a seventy-day harvest window from one strip.
- The full footprint runs one hundred calendar days end to end.
- Six short rows beat one long glut-sowing every time.
- Water the shallow July repeats or watch them fail to sprout.
Maturity and Sensible Intervals
Days to harvest for the succession crops here with the interval ranges that keep batches distinct rather than simultaneous. Fast crops tolerate tighter relays; slow-rooted crops want the longer gap or the later batches simply merge into the first.
| Crop | Days | Good interval | Watch out for |
|---|---|---|---|
| Radish | 30 | 10-14 d | Pithiness in heat |
| Lettuce | 45 | 10-14 d | Summer bolting |
| Spinach | 45 | 14 d | Bolt after 70°F |
| Cucumber | 55 | 14-21 d | Frost on late batches |
| Beet | 55 | 14-21 d | Cramped repeats |
| Bush bean | 60 | 14-21 d | Powdery mildew late |
| Carrot | 70 | 21-30 d | Hot-soil germination |
Key Terms
- Succession planting
- Relaying the same crop at intervals so harvests stagger across the season.
- Batch
- One sowing in the sequence, here always six of them to a plan.
- Interval
- Days between sowings, the dial that sets the pace of the harvest calendar.
- Harvest window
- The season length covered by staggered batches once picking begins.
- Relay sowing
- Starting the next strip as the previous one is established, market-garden rhythm.
How Market Gardeners Relays Work
- The interval is set by how fast the crop is eaten, not how fast it grows: a household picking radishes weekly can sow every fortnight, while a bean family feasting daily needs the shorter fifteen-day rhythm.
- Small, frequent plantings beat big, rare ones, which is the whole economics of the six-batch layout: ten feet every two weeks outsprints sixty feet at once on total yield and on morale.
- Fast crops are where succession pays, since a 30 to 60 day maturity lets six batches fit inside one season, while a 90-day tomato simply does not relay, it just ripens once and gorges you.
- The calendar flips in mid-July: the last batches of spring relays become the first of fall crops, and a spinach sowing in late summer is a winter-harvest plan wearing the same arithmetic.
- Watering is the failure point of later batches, because July-into-August germination needs moisture at the seed line daily, and most abandoned successions die at the crumb-crust stage, not the plate.
Common Mistakes & Fixes
- Sowing the full bed each round, which lands you with six simultaneous glut weeks instead of a staggered table.
- Running the last bean or cucumber batch blindly into the frost calendar, then losing it to one early night.
- Repeating spinach straight through July heat and then blaming the seed packet for bolting the batch.
- Forgetting to water the shallow new sowings through midsummer wind and sun-baked crust.
- Using one interval for radish and carrot alike, when the fast and slow math clearly suits neither.
- Letting the printed six batches imply permission to skip the fourth or fifth sowing when the freezer fills.
When to Use This (and When Not To)
Use it for anything you eat continuously rather than harvest once: salads, roots, bush beans and the spring radish run all reward a relay. It is the wrong tool for single-harvest fruiting crops like tomatoes and squash, which belong on the harvest-date projection instead. Pair it with the frost-date calculator whenever the sixth batch starts pointing at October, and with the seed-starting date tool when the repeats are indoors.
Succession Planting Calculator: Frequently Asked Questions
How often should I succession sow?
Every 10 to 21 days for most quick crops, tighter for salads and radishes and looser for beans and roots. The interval controls the harvest window directly: five intervals of spread plus one maturity is how long the plan keeps producing.
What vegetables are best for succession planting?
Radish, lettuce, spinach, beets, bush beans and carrots are the classic relays, all maturing inside sixty or seventy days and all eaten continuously rather than harvested at once. Full-season tomatoes and squashes are single-crop plants, not succession candidates.
How late can I succession sow before frost?
Back up a full maturity count plus a week of margin from your first fall frost, and if that date has passed the sowing, the plan has too. The calculator's last harvest line is exactly that check printed for every batch.
Do I really need six batches?
Six is the printed layout, not a rule, and four relays often cover a household better than six that outrun the freezer. The date math is identical either way, just less paper on the potting bench.
Why do my later sowings germinate worse?
Because hot July soil and a drying crust punish shallow seed, not because the seed is bad, and the fix is light daily misting until the repeat batch is up. Succession plans live or die on watering discipline in week three.
Can succession planting replace a big garden?
For salad and vegetable eating, largely yes, because a few short rows every fortnight produce continuously where one large planting produces one large week. Space savings are real, and the calendar is the whole method.
Sources & Further Reading
- Successional Planting for Continuous Harvest — University of Vermont Extension. Basis for interval ranges and batch-size guidance.
- Market Gardening: Relay Sowings — Cornell Cooperative Extension. Source of the small-frequent-planting economics.
- Fall Planting Dates for Vegetable Gardens — Penn State Extension. Supports the frost-countdown check on late batches.
Chlorova Gardening Team
Builds, checks and documents every tool we publish
Chlorova editorial review
Checked against extension-service publications
Formula verified against published references · Updated
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