Starting Seeds Indoors
Starting seeds indoors extends your season and saves money versus transplants. The key is counting backward from your last frost date.
Count back from last frost
Most warm crops want 6 weeks indoors. The calendar shows your indoor start date automatically once you pick your state and crop.
Light and warmth
Seedlings need bright light (a south window or grow light) and steady warmth (65–75°F). Leggy plants mean not enough light.
Harden off
A week before transplant, set seedlings outside for increasing periods to toughen them. Plant out after the last frost risk passes.
Planting Calendar (indoor start dates)
Use the free tool below with your own numbers — results are printable.
In California (typical zone 5–11), last frost ≈ Feb 15, first frost ≈ Dec 1 (289-day season), your Tomato plan:
Month-by-month (California, 2026)
| Month | Action |
|---|---|
| Jan | Start indoors |
| Feb | — |
| Mar | Sow · Transplant |
| Apr | — |
| May | Harvest |
| Jun | — |
| Jul | — |
| Aug | — |
| Sep | — |
| Oct | — |
| Nov | — |
| Dec | — |
Start indoors 6 weeks before last frost; transplant after soil warms. Zones 3–13 suitable. Dates are typical; confirm with your county extension and watch the 10-day forecast.
ZoneFig guidance is educational, based on USDA zones and extension guidelines. Confirm local freeze dates, product labels, and regulations with your county extension.