When to Plant Tomatoes

Planting time for tomatoes is set by your frost dates, not by the calendar month. Start seeds indoors about 7 weeks before your last spring frost, then transplant about 2 weeks after it. From there it takes roughly 75 days to the first harvest. Tomatoes is a tender crop, and a single light frost ends it, so both ends of its season are hard boundaries. Pick your zone below for exact dates, or find your zone by ZIP if you are not sure which one you are in.

A second tomato crop only works where the first fall frost is late enough to finish it, which in practice means zone 9 and warmer. Because it is a tender crop, the fall sowing has to finish before the first frost with no margin for error, so the sow-by dates in the table above are hard deadlines rather than suggestions.

Fall dates are counted backward from your first frost, not forward from a sowing date. Take the 75 days tomatoes needs, add about two weeks because growth slows once days shorten after the equinox, then add two more weeks of margin because frost kills it outright. That is 103 days before your first frost. The coldest zone where this still works on the averages is Zone 6a.

For the whole-garden version of this arithmetic, see the fall planting calendar by zone, and how to read and stretch your first frost date.

Tomatoes grow well next to basil, carrots, onions and parsley. Keep them away from potatoes, corn and eggplant. Shares early and late blight with potatoes and eggplant, and corn draws the same fruitworm moth. The full grid for all 24 crops is in the companion planting chart.