When should I plant zucchini in ZIP 53202?

In ZIP 53202, the main zucchini target is around May 20, based on the representative Milwaukee frost station and USDA zone 6a.

When should I start zucchini seeds indoors in 53202?

Start zucchini seeds indoors in ZIP 53202 around Apr 19, about 21 days before the May 10 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 53202 planting calendar

When to plant zucchini in Milwaukee, WI - Zone 6a

Q: When is the first frost in Milwaukee?

Milwaukee (ZIP 53202) has an average first fall frost around Oct 10, leaving about 153 frost-free days.

In ZIP 53202, plant zucchini around May 20; this uses the Milwaukee frost station, USDA zone 6a, and zucchini timing rules.

Your Milwaukee calendar has a 153-day estimated frost-free season. This estimate uses the representative Milwaukee frost station, USDA zone 6a, and zucchini timing rules.

Source: milwaukee-mitchell frost station, USDA zone 6a, 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 6a Milwaukee frost station University of Wisconsin Extension Updated 2026-06-28

Read the method

Answer first

When to start zucchini seeds indoors in Milwaukee

In ZIP 53202, start zucchini seeds indoors around Apr 19, about 21 days before the May 10 last-frost estimate.

Start zucchini seeds indoors in Milwaukee around Apr 19, about 21 days before the May 10 last-frost estimate.

Seed starting schedule

Zucchini dates for Milwaukee, WI

Step	Date	How to use it
Start Indoors	April 19, 2026	Start seeds under lights or in a bright indoor seed-starting space.
Transplant Outdoors	May 20, 2026	Move hardened-off seedlings outside after the frost-risk window.
Direct Sow	May 20, 2026	Sow seed outside when the crop and soil can handle the window.

Last frost

When is the last frost in Milwaukee?

Milwaukee (ZIP 53202) has an average last spring frost around May 10.

First frost

When is the first frost in Milwaukee?

The average first fall frost is around Oct 10, giving about 153 frost-free days.

Season map

Zucchini windows by month

JanFebMarAprMayJunJulAugSepOctNovDec

Start indoors

Apr 19

Direct sow

May 20

Transplant

May 20

Harvest

Jul 14

Frost watch

Aug 16

Reminder workflow

Every date has a next action

Start zucchini indoorsApr 19

Last frost windowMay 10

Direct sow zucchiniMay 20

Transplant zucchiniMay 20

First zucchini harvest windowJul 14

Last zucchini sowing targetAug 16

Signal	Value	Why it matters
Last frost estimate	May 10, 2026	Warm-season transplant risk starts falling after this window.
First frost estimate	October 10, 2026	Fall planting counts backward from this date.
Season length	153 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

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

University of Wisconsin 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 10. A conservative last sowing target is around Aug 16.