Zone 5a covers 2,426 ZIP codes in 19 states on the 2023 map, most of them in Iowa, Minnesota, Wisconsin, Vermont and South Dakota. Cities in it include Minneapolis and Saint Paul in Minnesota, Billings in Montana, Sioux Falls in South Dakota and Anchorage in Alaska.

Zone 5a Planting Calendar and Hardy Plants (-20°F to -15°F)

Q: What does zone 5a mean?

Zone 5a means the coldest night of the winter averages -20°F to -15°F, measured over 1991 to 2020. It is an average of each winter's lowest temperature, so some winters go colder.

Q: When is the last frost in zone 5a?

Across 449 NOAA stations in zone 5a, the median last spring frost is May 6 and the median first fall frost is Oct 3. Half the stations fall between Apr 30 and May 16 in spring, so check the date for your own ZIP before you plant.

Q: What can I plant in zone 5a?

47 of the plants listed here are rated for zone 5a by NC State Extension, including perennials such as purple coneflower, orange coneflower (black-eyed Susan) and daylily and fruit such as apple, peach and pear. Any plant rated for a range that includes 5a should come through a typical winter.

Q: What is the difference between zone 5a and 5b?

Five degrees. Zone 5a averages -20°F to -15°F and 5b averages -15°F to -10°F, so 5a is the colder half. A plant rated for zone 5 suits both.

Q: Will a plant rated for zone 5b survive in zone 5a?

Not reliably. A plant rated down to 5b is rated for winter lows of -15°F to -10°F, and a typical zone 5a winter reaches -20°F to -15°F. Choose plants whose range on the tag includes 5a.

2,426 ZIP codes

Where zone 5a is

Zone 5a covers 2,426 ZIP codes in 19 states: Iowa (563), Minnesota (271), Wisconsin (250), Vermont (176), South Dakota (168), Maine (151), New York (141), Michigan (132) and 11 more.

Across its 449 NOAA stations the last spring frost comes around May 6 and the first fall frost around Oct 3; half the stations fall between Apr 30 and May 16 in spring and Sep 29 and Oct 8 in fall.

Cities and towns in zone 5a

Tap a town for its own frost dates and this month’s jobs; a hill or a valley a few miles off can be half a zone either side.

Twelve months

Zone 5a planting calendar

What to start, sow, plant, divide, prune, mulch and protect in zone 5a, month by month. Every job names the extension service page it rests on; open “Where this comes from” under a job to read their words.

Timed from the median frost dates of the 449 NOAA stations in zone 5a: last spring frost May 6, first fall frost Oct 3. Your own ZIP’s frost dates move every window, so the ZIP tool times them for you.

Pick a month above to see every job in it.

The year at a glance

Start vegetable seeds indoorsJan to Apr
Sow vegetables in the gardenApr to May
Sow the fall vegetable gardenJun to Aug
Set out transplantsApr to May
Plant trees and shrubsMar 25 to May 20 and Sep 19 to Nov 7
Plant garlicSep 19 to Oct 24
Plant tulips and other spring bulbsOct 10 to Oct 17
Divide fall-blooming perennialsApr 15 to May 27
Divide spring and summer-blooming perennialsAug 22 to Oct 3
Prune trees and summer-flowering shrubs while dormantFeb 25 to Apr 8
Prune spring-flowering shrubs after they bloomApr 22 to Jun 17
Water evergreens and new plantings until the ground freezesSep 5 to Nov 14
Mulch perennial crowns once the ground freezesNov 14 to Nov 28
Pull back the winter mulchMar 18 to Apr 1
Put hardware cloth around young tree trunksOct 3 to Nov 14
Dig and store canna, dahlia and gladiolusOct 3 to Oct 10
Cut back perennials after a hard freezeOct 10 to Nov 7

47 plants

What grows in zone 5a

Perennials, shrubs, trees and fruit that NC State Extension rates as hardy in zone 5a, each linked to its plant page. A plant rated for a range of zones suits every half zone in it, so “zones 4 to 8” covers 4a through 8b.

Perennials 15

Purple coneflowerzones 3a to 8b
Orange coneflower (black-eyed Susan)zones 3a to 9b
Daylilyzones 3a to 9b
Hostazones 3a to 9b
Catmintzones 5a to 9b
Woodland sagezones 4a to 8b
Coral bells (American alumroot)zones 4a to 9b
Butterfly weedzones 3a to 9b
Blue false indigozones 3a to 9b
Yarrowzones 3a to 9b
Garden phloxzones 4a to 8b
English lavenderzones 5a to 9b
Siberian iriszones 3a to 8b
Showy stonecrop (sedum)zones 4a to 9b
Rose mallowzones 4a to 9b

Shrubs 11

Smooth hydrangeazones 3a to 9b
Common lilaczones 3a to 7a
Forsythiazones 5a to 8b
Japanese spireazones 3a to 8b
Arrowwood viburnumzones 2a to 8b
Red twig dogwoodzones 2a to 7b
Winterberry hollyzones 3a to 9b
Catawba rhododendronzones 4a to 8b
Common boxwoodzones 5a to 8b
Rose of Sharonzones 5a to 9b
Black chokeberryzones 3a to 8b

Trees 6

Red maplezones 2a to 9b
Eastern redbudzones 4a to 9b
Flowering dogwoodzones 5a to 9b
Paper birchzones 2a to 7a
Colorado blue sprucezones 2a to 7a
Serviceberryzones 3a to 8a

Fruit 10

Applezones 4a to 9b
Peachzones 5a to 9b
Pearzones 4a to 8b
Sweet cherryzones 3a to 8b
Highbush blueberryzones 3a to 8b
Red raspberryzones 4a to 8b
Garden strawberryzones 5a to 9b
Muscadine grapezones 5a to 9b
American persimmonzones 4a to 9b
Pawpawzones 5a to 9b

Bulbs 3

Tulipzones 3a to 8b
Daffodilzones 4a to 8b
Lilyzones 3a to 8b

Perennial vegetables 2

Garliczones 4a to 9b
Asparaguszones 2a to 9b

Ratings from the NC State Extension Gardener Plant Toolbox, read Oct 9, 2026. The zone covers winter cold only; heat, rain and soil decide the rest.

A summer perennial border of yellow black-eyed Susans, purple liatris spikes and silvery Russian sage, with a rose of Sharon shrub behind and small plant labels in the bed — A labeled perennial border in high summer. The zone on a plant tag is the coldest winter it is rated to come through, so a plant rated for zones 4 to 9 suits every half zone from 4a to 9b. “Perennials border in Summer”, Bindersbee, Public domain

Either side

The zones next to 5a

Each half zone is five degrees. Zone 4b is five degrees colder at -25°F to -20°F. Zone 5b is five degrees warmer at -15°F to -10°F.

Zone 4b, colder-25°F to -20°F Zone 5b, warmer-15°F to -10°F

Questions

Zone 5a questions

What does zone 5a mean?

Where is zone 5a?

When is the last frost in zone 5a?

What can I plant in zone 5a?

What is the difference between zone 5a and 5b?

Will a plant rated for zone 5b survive in zone 5a?

Your own dates, by ZIP

Find your zone by ZIPYour zone, your frost dates and this month’s jobs for your address.Seed starting calendarWhen to start each vegetable indoors, by ZIP.Frost dates by ZIPYour last spring and first fall frost, with the odds either side.First frost forecastWhen the first fall frost usually arrives, state by state.Soil temperatureWhen the ground is warm enough to sow.When to plant garlicThe fall planting window by ZIP.

Sources. USDA Plant Hardiness Zone Map, ZIP code tables (2023 and 2012), PRISM Climate Group, Oregon State University; USDA Plant Hardiness Zone Map; USDA Unveils Updated Plant Hardiness Zone Map (USDA Agricultural Research Service, November 15, 2023); NOAA NCEI U.S. Climate Normals 1991-2020, annual/seasonal, by station (v1.0.1); NC State Extension Gardener Plant Toolbox. Zone frost dates are the medians of the NOAA 1991 to 2020 station normals inside the zone.

The calendar’s extension sources:

UNH Cooperative Extension, Growing Vegetables: When to Plant your Vegetable Garden, read Sep 21, 2026.
University of Minnesota Extension, Planting vegetables in midsummer for a fall harvest, read Oct 9, 2026.
University of Illinois Extension, Planting a fall vegetable garden (Good Growing), read Oct 9, 2026.
University of Minnesota Extension, Dividing perennials, read Oct 9, 2026.
Iowa State University Extension and Outreach, How should I prepare my perennial beds for winter?, read Oct 9, 2026.
University of Minnesota Extension, Pruning trees and shrubs, read Oct 9, 2026.
Rutgers NJAES Cooperative Extension, Pruning Flowering Shrubs (FS1221), read Oct 9, 2026.
University of Maryland Extension, Planting a Tree or Shrub, read Oct 9, 2026.
University of Wisconsin-Madison Division of Extension, Preparing Landscape Plants for Winter, read Oct 9, 2026.
University of Wisconsin-Madison Division of Extension, Storing Tender Bulbs for Winter, read Oct 9, 2026.
Iowa State University Extension and Outreach, All About Tulips, read Oct 9, 2026.
UF/IFAS Gardening Solutions, Tulips, read Oct 9, 2026.
UF/IFAS Gardening Solutions, Preparing the Landscape for Cold Weather, read Oct 9, 2026.
UF/IFAS Gardening Solutions, Treating Cold-Damaged Plants, read Oct 9, 2026.