Planting Guides

When to Plant Squash in Anchorage: Complete Guide + Best Varieties for Zone 4b

Anchorage, Alaska

USDA Zone 4b

Last Frost: May 20

Last updated: October 30, 2025

Plant squash in Anchorage after May 19 with season-extending techniques. Focus on summer varieties that mature in 118 days or less for Alaska's short growing season.

TTom Erikson

October 30, 2025

Squash growing with season extension in Anchorage Alaska Zone 4b garden — — Image © PlantReference.org 2026

Quick Answer

Start squash seeds indoors April 25, transplant outdoors May 26. Focus on summer varieties under protection.

TL;DR

Plant squash in Anchorage after May 19 when soil reaches 60°F (15°C). Focus on summer varieties like zucchini and yellow crookneck that mature in 45-60 days. Winter squash requires season extension with plastic mulch and row covers to succeed in Alaska's 118-day growing season.

Frequently Asked Questions

When should I start squash seeds indoors in Anchorage?

Start squash seeds indoors on April 25 for transplanting after the last frost date of May 19. Seeds germinate in 5-7 days at 70-75°F (21-24°C). Use biodegradable peat pots to avoid root disturbance during transplanting, which is critical for successful establishment in Alaska's challenging conditions.

Can winter squash grow successfully in Anchorage's short season?

Winter squash is extremely challenging in Anchorage's 118-day growing season. Only the shortest-season varieties like Cucurbita pepo 'Delicata' (80-100 days) have potential with intensive season extension techniques including black plastic mulch, row covers, and early indoor starts. Most gardeners achieve better success focusing on summer squash varieties.

What soil temperature is needed before transplanting squash in Alaska?

Soil must reach 60°F (15°C) consistently at 4-inch depth before transplanting squash outdoors. Install black plastic mulch 4-6 weeks before your planned transplant date to warm the soil. Cold soil below 60°F stops root development and can kill transplants even if air temperatures are acceptable.

How do I protect squash from late spring frost in Anchorage?

Use floating row covers immediately after transplanting in late May. These spun-bonded polyester covers provide 4-8°F of frost protection while allowing light penetration. Keep covers ready through mid-June, as late frost can occur. Wall O' Water individual plant protectors offer even more protection for single plants.

What's the best squash variety for Alaska's Zone 4b climate?

Cucurbita pepo 'Black Beauty' zucchini is the most reliable variety for Anchorage. It matures in just 45-55 days, starts producing by mid-July, and continues until frost. One plant produces enough for a family throughout the season. Yellow crookneck is another excellent choice with similar timing and better cool-weather tolerance.

How long is Anchorage's growing season for squash?

Anchorage has 118 frost-free days from May 19 to September 14. This limits you to summer squash varieties and the very shortest-season winter types. Focus on varieties that mature in 60 days or less for reliable harvest, though longer varieties may succeed with season extension techniques and favorable weather.

Should I use raised beds for growing squash in Alaska?

Yes, raised beds are essential in Alaska for several reasons. They improve drainage in Alaska's wet climate, warm up faster in spring, and allow better soil control. Build beds at least 8 inches high with well-draining soil mix. Install black plastic mulch on raised beds to maximize soil warming in the short growing season.

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Tagged with

#when to plant squash anchorage #anchorage alaska gardening #zone 4b vegetables #alaska squash growing #short season squash #anchorage planting dates #alaska vegetable gardening #season extension techniques #black plastic mulch #floating row covers

Written By

Tom Erikson

Tom is a lifelong Alaskan who gardens in Anchorage, where the growing season is short but intense. He works for the state cooperative extension service and has spent years figuring out what works in a climate where the ground freezes deep, the growing season starts in late May, and you get 19 hours of daylight in June. Tom grows cold-hardy vegetables, maintains a collection of boreal-adapted perennials, and experiments with season extension using cold frames and row covers. He writes about the realities of northern gardening—the unique advantages (those long summer days produce remarkable growth) and the genuine limitations. Tom's tone is calm and practical, with the quiet humor of someone who's gardened through Alaskan winters for decades.