When is the last frost in Portage, MI?

The average last spring frost (50% probability of 32°F) in Portage is around April 28, based on NOAA/NCEI 1991–2020 normals at the Kalamazoo Battle Ck Intl Ap, MI station (2.6 mi away). Half of years it falls outside that date, so wait 1–2 weeks past it before setting out frost-tender plants.

When is the first fall frost in Portage?

The average first fall frost in Portage, MI is around October 18, giving roughly a 172-day frost-free growing season.

What planting zone is Portage, MI?

Portage is in USDA plant hardiness zone 6a (average annual extreme minimum temperature -10 to -5°F), from the 2023 USDA Plant Hardiness Zone Map.

What is the weather like in Portage?

In Portage, MI the warmest month is July (avg high 83.1°F) and the coldest is January (avg low 18.1°F). It averages about 33.2″ of precipitation a year.

Home › Michigan › Portage

Portage, MI Planting Calendar & Frost Dates

USDA hardiness zone 6a · ZIP 49002 · elevation 265′ · NOAA & USDA data

Portage is in USDA hardiness zone 6a (winters can dip to -10 to -5°F), with a growing season of about 172 days between the average last spring frost (April 28) and first fall frost (October 18). The warmest month is July (avg high 83.1°F); the coldest is January (avg low 18.1°F). It averages 33.2″ of precipitation a year. Start cool-season crops several weeks before the last frost; wait until after it for tomatoes, peppers and other tender crops.

Hardiness zone

min temp -10 to -5°F

Last spring frost

April 28

avg (50% prob, 32°F)

First fall frost

October 18

avg (50% prob, 32°F)

Growing season

172 days

frost-free window

Warmest month

July

avg high 83.1°F

Month-by-month typical weather in Portage

Average conditions from the NOAA/NCEI 1991–2020 U.S. Climate Normals at Kalamazoo Battle Ck Intl Ap, MI (2.6 mi away). Temperatures °F, precipitation & snow in inches.

Month	Avg high	Avg low	Mean	Precip (in)	Snow (in)
January	31.5	18.1	24.8	1.7	–
February	34.7	19.5	27.1	1.3	–
March	45.9	27.3	36.6	2	–
April	59.3	37.7	48.5	3.1	–
May	70.3	48.7	59.5	3.7	–
June	79.5	58.1	68.8	3.2	–
July	83.1	62	72.6	3.4	–
August	81.1	60.4	70.8	3.7	–
September	74.1	52.5	63.3	3.3	–
October	61.3	41.9	51.6	3.7	–
November	47.6	32.5	40.1	2.5	–
December	36.5	24.2	30.4	1.7	–

What to plant when in Portage

Crop	Season	What to do & when
Tomatoes	warm	Start seeds indoors: March 17 · Transplant out: May 5
Peppers	warm	Start seeds indoors: March 3 · Transplant out: May 12
Cucumbers	warm	Direct sow: May 5
Zucchini / squash	warm	Direct sow: May 5
Bush beans	warm	Direct sow: May 5
Sweet corn	warm	Direct sow: May 5
Basil	warm	Transplant out: May 5
Peas	cool	Sow (spring): March 24 · Sow (fall): August 23
Spinach	cool	Sow (spring): March 17 · Sow (fall): August 23
Lettuce	cool	Sow (spring): March 31 · Sow (fall): August 23
Kale	cool	Transplant (spring): April 7 · Sow (fall): August 9
Broccoli	cool	Transplant (spring): April 14
Carrots	cool	Sow (spring): April 7 · Sow (fall): August 9
Onions	cool	Transplant (spring): March 31
Potatoes	cool	Plant seed potatoes: April 14
Radishes	cool	Sow (spring): March 31 · Sow (fall): September 6

Dates are computed from Portage's average frost dates using standard cool-/warm-season timing. They're a starting point — a cold spring, a warm microclimate, or a fast-maturing variety can shift them by a week or two.

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Gear that helps you plant on time

Some links below are Amazon affiliate links (tag theboringthin-20). If you buy through them we may earn a small commission at no extra cost to you — it keeps this almanac free. We only list generic, genuinely-useful categories.

Soil thermometer →Know when the ground is warm enough to sow — the honest signal, not the calendar.Seed-starting trays + dome →Start tomatoes & peppers indoors on the schedule below.Seedling heat mat →Warms the soil for faster, more even germination indoors.Floating row cover / frost cloth →Buys you 4–8°F to beat an early or late frost.Raised garden bed kit →Warms and drains faster in spring than in-ground soil.Garden gloves →Basic kit for transplant day.

Nearby cities in Michigan

Kalamazoo, MI Battle Creek, MI Wyoming, MI Grand Rapids, MI Lansing, MI East Lansing, MI Muskegon, MI Ann Arbor, MI

Sources & method. Hardiness zone: 2023 USDA Plant Hardiness Zone Map (PRISM Climate Group, Oregon State University). Frost dates & growing season: NOAA/NCEI 1991–2020 U.S. Climate Normals, nearest station with published freeze normals — Kalamazoo Battle Ck Intl Ap, MI, 2.6 mi (confidence: high). Monthly weather normals: Kalamazoo Battle Ck Intl Ap, MI, 2.6 mi (confidence: high). ZIP centroid from U.S. Census 2023 ZCTA data. Frost dates are the 50%-probability date — half of years frost occurs outside the stated date. Nothing here is invented; where the nearest station is far, we say so. Last updated 2026-07-22.