Sowing-date back-calculator (when to plant for a target harvest)
Pick a target harvest date — Thanksgiving turkey-stuffing tomatoes, a Mother's Day lettuce harvest, the first farmers-market table of the season — and we tell you when to start each crop based on days-to-maturity. Direct-seeded and transplanted both shown.
How does back-calculation work?
Subtract the crop's days-to-maturity from your target harvest date and you have your sowing window. For transplanted crops, also subtract the time spent indoors so the seedling is ready to go in the ground at the right calendar date. The math is simple — what makes it useful is having all your crops on one page so you can see the cascade of "start tomatoes this week, peppers two weeks ago (oops), garlic eight months ago" without paging through seed packets.
Days to maturity for common vegetables
| Crop | From seed | From transplant | Start indoors (weeks before) |
|---|---|---|---|
| 🍅 Tomato | 75 d | 65 d | 6 wk |
| 🌶️ Pepper | 80 d | 70 d | 8 wk |
| 🥬 Lettuce | 50 d | — | direct only |
| 🥬 Spinach | 45 d | — | direct only |
| 🥕 Carrot | 70 d | — | direct only |
| 🥬 Radish | 28 d | — | direct only |
| 🥬 Beet | 60 d | — | direct only |
| 🥒 Cucumber | 60 d | 50 d | 4 wk |
| 🥒 Zucchini | 55 d | — | direct only |
| 🎃 Winter squash | 100 d | — | direct only |
| 🎃 Pumpkin | 110 d | — | direct only |
| 🫘 Bean (bush) | 55 d | — | direct only |
| 🫘 Bean (pole) | 70 d | — | direct only |
| 🌱 Pea | 65 d | — | direct only |
| 🌽 Sweet corn | 80 d | — | direct only |
| 🥦 Broccoli | 75 d | 60 d | 6 wk |
| 🥬 Cabbage | 80 d | 65 d | 6 wk |
| 🥬 Cauliflower | 80 d | 65 d | 6 wk |
| 🥬 Kale | 60 d | — | direct only |
| 🧅 Onion (from set) | 110 d | — | direct only |
| 🧄 Garlic (overwinter) | 240 d | — | direct only |
| 🥔 Potato | 90 d | — | direct only |
| 🍉 Watermelon | 90 d | — | direct only |
The realistic caveats
Days-to-maturity numbers are variety-specific and slightly optimistic — most seed packets state the count from transplant for transplanted crops, and from sowing for direct-seeded. Cold early-season weather slows everything; a heatwave can speed fruiting types. Treat the dates above as a planning baseline, not a calendar guarantee. The compounding error gets bigger the further you push toward fall — for late-fall harvests, add 7-14 days of buffer.
Plan a whole season, not one harvest
Farm Planner lets you set succession-planting dates per crop, warns you before tomato goes back where tomato just came out, and surfaces every sowing/transplant/harvest task on the daily briefing. Free 30-day trial.