Plant Tomatoes in Zone 3b
Seed-starting, transplant & harvest dates for USDA Zone 3b
Zone 3b averages 128 frost-free days, running from a last spring frost around May 13 to a first fall frost around September 18. Tomatoes needs roughly 75 days from planting out to first harvest, so it uses about 59 percent of that window. Tomatoes is a tender crop, which is what decides where in the window it belongs.
Because tomatoes needs a head start, sow seed indoors around Mar 25, about 7 weeks ahead of the Zone 3b last frost. Transplants go out around May 27. Starting earlier than that in Zone 3b usually backfires: plants outgrow their cells and stall when they finally hit cold soil.
Fall planting: tomatoes in Zone 3b
Tomatoes has no useful fall window in Zone 3b. 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.
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.
Fall dates are counted backward from the Zone 3b average first frost, not forward from a sowing date. See the fall planting calendar by zone for the full method.
Spring vs fall tomatoes in Zone 3b
| Planting | Sow or start | In the ground | Harvest |
|---|---|---|---|
| Spring | Mar 25 | May 27 | Aug 10 |
| Fall | — | — | — |
Tomatoes in nearby zones
Further reading on tomatoes
- When to start seeds indoors by zone
Indoor start dates for tomatoes, counted back from your last frost.
- Hardening off seedlings: a schedule
A day by day plan for moving tomatoes seedlings outdoors.
- Best grow lights for seed starting
What light seedlings actually need, and which fixtures deliver it.
Other crops in Zone 3b
Frequently asked questions
When should I start tomatoes in Zone 3b?
Start tomatoes seeds indoors around Mar 25 (Zone 3b).
Can I direct sow tomatoes in Zone 3b?
Tomatoes is best started indoors and transplanted in Zone 3b rather than direct sown.
Can I plant tomatoes in the fall in Zone 3b?
Tomatoes has no useful fall window in Zone 3b. 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.
Will tomatoes survive frost in Zone 3b?
No. Tomatoes is a tender crop and a single light frost ends it, so every Zone 3b planting has to finish before the average first frost.