When should I plant lettuce in ZIP 48226?

In ZIP 48226, the main lettuce target is around Apr 21, based on the representative Detroit frost station and USDA zone 6b.

When should I start lettuce seeds indoors in 48226?

Start lettuce seeds indoors in ZIP 48226 around Apr 7, about 28 days before the May 5 last-frost estimate.

Is this a guaranteed planting date?

No. GrowZone uses frost-date estimates, hardiness zones, and crop timing rules for planning. Local microclimates and current weather can shift the right date.

ZIP 48226 planting calendar

When to plant lettuce in Detroit, MI - Zone 6b

Q: When is the first frost in Detroit?

Detroit (ZIP 48226) has an average first fall frost around Oct 15, leaving about 163 frost-free days.

In ZIP 48226, plant lettuce around Apr 21; this uses the Detroit frost station, USDA zone 6b, and lettuce timing rules.

Your Detroit calendar has a 163-day estimated frost-free season. This estimate uses the representative Detroit frost station, USDA zone 6b, and lettuce timing rules.

Source: detroit-metro frost station, USDA zone 6b, last updated 2026-06-28. Verify locally before planting high-value crops because microclimates, current weather, and yard exposure can move the safe date.

USDA zone 6b Detroit frost station Michigan State University Extension Updated 2026-06-28

Read the method

Answer first

When to start lettuce seeds indoors in Detroit

In ZIP 48226, start lettuce seeds indoors around Apr 7, about 28 days before the May 5 last-frost estimate.

Start lettuce seeds indoors in Detroit around Apr 7, about 28 days before the May 5 last-frost estimate.

Seed starting schedule

Lettuce dates for Detroit, MI

Step	Date	How to use it
Start Indoors	April 7, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	April 21, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	April 21, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Detroit?

Detroit (ZIP 48226) has an average last spring frost around May 5.

First frost

When is the first frost in Detroit?

The average first fall frost is around Oct 15, giving about 163 frost-free days.

Season map

Lettuce windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Apr 7

Direct sow

Apr 21

Transplant

Apr 21

Harvest

Jun 15

Frost watch

Aug 21

Reminder workflow

Every date has a next action

Start lettuce indoorsApr 7

Direct sow lettuceApr 21

Transplant lettuceApr 21

Last frost windowMay 5

First lettuce harvest windowJun 15

Last lettuce sowing targetAug 21

Signal	Value	Why it matters
Last frost estimate	May 5, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	October 15, 2026	Fall planting counts backward from this date.
Season length	163 days	Longer seasons can support succession crops.
Spacing	8-12 in	Airflow and root space affect yield.
Soil temperature	40 F+	Seeds and transplants stall in cold soil.

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Local data

Why this date changes by ZIP

Detroit frost history and USDA zone 6b shift the safe planting window. GrowZone uses a local representative station instead of one national rule.

Michigan State University Extension is the kind of local source to verify against when a crop is expensive, weather is unusual, or your yard has a cold pocket.

Crop note

Lettuce timing notes

Succession sow every 10-14 days while weather is cool. Lettuce prefers sun to part shade, 8-12 in spacing, and soil near 40 F+.

For fall, count backward from Oct 15. A conservative last sowing target is around Aug 21.