When should I plant zucchini in ZIP 48226?

In ZIP 48226, the main zucchini target is around May 15, based on the representative Detroit frost station and USDA zone 6b.

When should I start zucchini seeds indoors in 48226?

Start zucchini seeds indoors in ZIP 48226 around Apr 14, about 21 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 zucchini 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 zucchini around May 15; this uses the Detroit frost station, USDA zone 6b, and zucchini 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 zucchini 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 zucchini seeds indoors in Detroit

In ZIP 48226, start zucchini seeds indoors around Apr 14, about 21 days before the May 5 last-frost estimate.

Start zucchini seeds indoors in Detroit around Apr 14, about 21 days before the May 5 last-frost estimate.

Seed starting schedule

Zucchini dates for Detroit, MI

Step	Date	How to use it
Start Indoors	April 14, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	May 15, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	May 15, 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

Zucchini windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Apr 14

Direct sow

May 15

Transplant

May 15

Harvest

Jul 9

Frost watch

Aug 21

Reminder workflow

Every date has a next action

Start zucchini indoorsApr 14

Last frost windowMay 5

Direct sow zucchiniMay 15

Transplant zucchiniMay 15

First zucchini harvest windowJul 9

Last zucchini 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	24-36 in	Airflow and root space affect yield.
Soil temperature	65 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

Zucchini timing notes

One or two healthy plants can feed a household. Zucchini prefers full sun, 24-36 in spacing, and soil near 65 F+.

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