Seed starting calendar
Every "start seeds indoors" date is arithmetic: last spring frost minus the weeks a crop needs. Put your frost date in below and the whole schedule falls out.
How to use it
- Type your last spring frost date, or pick a USDA zone to fill in an approximate one.
- Read the "start indoors" window and the "set out" date for each crop.
- Sow at the end of the window if your indoor space is small — late is safer than early.
Your schedule
Pick a frost date to build the table.
| Crop | Start indoors | Set out | Method |
|---|
How the dates are worked out
Each crop has a window measured back from the last spring frost — the average date after which no frost is expected in your area. Tomato, for example, needs six to eight weeks indoors, so with a May 10 frost date it is sown between March 15 and March 29.
Two rules keep the table honest. First, the frost date is an average, not a promise: in a cold year your last frost can come a week or two later, so keep row cover or a cold frame ready for anything set out early. Second, the weeks are the plant's actual need, not a preference — sowing a pepper in January produces a leggy plant sitting in the same tray in April.
If you are starting more than about four weeks before your frost date, plan light as well as dates: seedlings that lean toward a window never recover their shape. The seed starting basics guide covers the setup side of this, and the tray guide covers how much space you actually need.
Tools for this job
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Seed starting tray with humidity dome
A covered 72-cell tray holds warmth and moisture until the first sprouts show.
Seedling heat mat
Soil at 70-75F is what makes peppers and eggplant germinate at all.
LED grow light for seedlings
Keeps starts from stretching when the February window is not enough.
Related guides
Frequently asked questions
How do I find my last spring frost date?
Search "last frost date" plus your town, or call your county extension office — they publish the average date for your area. If you only know your USDA zone, pick it in the dropdown and the calculator will fill in an approximate date you can adjust.
What does "set out" mean in the table?
It is the date the seedling can move to the garden, counted from the last frost date. Tomatoes and marigolds go out at frost date; peppers, eggplant and basil need one to two weeks of warm soil after it.
Can I start seeds later than the calendar says?
Yes. Starting later costs you a week or two of growth, not the season. Starting earlier than the window is the worse mistake: seedlings that outgrow their tray in March are hard to keep alive until the soil warms.
Why do peppers need more weeks indoors than cucumbers?
Peppers grow slowly from seed and need a long head start to fruit before autumn. Cucumbers germinate in days and grow fast, so an early start only produces a root-bound plant that sulks after transplanting.
Do I need a grow light?
For anything started more than four weeks before your frost date, yes — a south-facing window is usually not enough in late winter and seedlings stretch toward weak light. A cheap shop light a few inches above the tray is enough.
Is this calendar right for my state?
It is arithmetic from your own frost date, so it works anywhere in the US. The zone dropdown is only a shortcut for the frost date; the date you type in is what the table uses.