Juneau, Alaska Garden Guide: Planting Dates, Frost Dates & Growing Season

Growing Season Snapshot

Typical last spring frost May 3

Typical first fall frost October 14

Typical frost-free days 164

GDD left on May 15 (base 50) 678

These season boundaries are climate normals, not a forecast. A 50% frost date means a 32°F frost arrives by that date in about half of years — and later in about half. Treat these dates as planning anchors, not guarantees.

Juneau Planting Calendar

A practical guide to when planting usually works in Juneau. These windows are based on climate normals (not a forecast) and line up with the 50% last spring frost and typical early-season heat.

Crop	Planting Window	Method	Best Variety	Local Fit
Cool-season / early window Cold-tolerant crops that usually handle cooler spring conditions better.
Peas	April 5 – April 19	direct sow	Little Marvel	Excellent fit
Spinach	April 5 – April 19	direct sow	Space	Excellent fit
Kale	April 9 – April 29	direct sow / transplant	Winterbor	Excellent fit
Beets	April 12 – April 26	direct sow	Detroit Dark Red	Excellent fit
Carrots	April 12 – April 26	direct sow	Bolero	Excellent fit
Lettuce	April 12 – April 26	direct sow / transplant	Buttercrunch	Excellent fit
Strawberries	April 12 – April 26	plant crowns / transplants	Seascape	Excellent fit
Onions	April 12 – April 26	sets / transplants	Copra	Good fit
Swiss Chard	April 13 – May 3	direct sow / transplant	Bright Lights	Excellent fit
Broccoli	April 19 – May 3	transplant	Packman	Excellent fit
Cabbage	April 19 – May 3	transplant	Stonehead	Excellent fit
Cauliflower	April 19 – May 3	transplant	Snow Crown	Excellent fit
Potatoes	April 19 – May 3	plant seed potatoes	Kennebec	Strong fit
Main warm-season window Crops that usually do best once frost risk fades and the season starts opening up more fully.
Beans	May 3 – May 17	direct sow	Provider	Risky fit
Sweet Corn	May 8 – May 18	direct sow	Yukon Chief	Risky fit
Basil	May 12 – May 22	direct sow / transplant	Prospera	Borderline
Cucumbers	May 12 – May 22	direct sow / transplant	Cool Breeze	Borderline
Zucchini	May 12 – May 22	direct sow / transplant	Dunja	Borderline
Melons	May 12 – May 22	direct sow / transplant	Minnesota Midget	Risky fit
Pumpkin	May 12 – May 22	direct sow / transplant	Small Sugar	Risky fit
Tomatoes	May 12 – May 22	transplant	Stupice	Risky fit
Watermelons	May 12 – May 22	direct sow / transplant	Sugar Baby	Risky fit
Winter Squash	May 12 – May 22	direct sow / transplant	Delicata	Risky fit
Peppers	May 19 – May 29	transplant	King of the North	Risky fit

How to use this: aim for the earlier part of each window for the most reliable results. Later planting can still work, but it usually depends more on variety maturity, warmer microclimates, and simple protection like row cover or low tunnels.

Common Timing Mistakes

These patterns show up again and again in Juneau — especially in typical years.

Waiting too long after last frost to plant warm-season crops, which compresses harvest timing.
Expecting late plantings to finish — cooling nights often slow crops earlier than expected.
Relying on calendar dates instead of crop maturity and typical frost timing.

Missed Your Planting Window? What Can You Still Grow?

This table shows what can still mature from several later-season planting dates in Juneau. It compares the growing degree days still typically available after each checkpoint with the heat each crop usually needs to finish, then applies a 15% safety margin to separate crops that usually still fit from ones that are more borderline.

Usually fits Borderline Too tight

Crop	Heat Units	May 15	Jun 1	Jul 1	Aug 1
Spinach	450 (base 40)	✅	✅	✅	✅
Lettuce	500 (base 40)	✅	✅	✅	✅
Strawberry	600 (base 40)	✅	✅	✅	✅
Pea	600 (base 40)	✅	✅	✅	✅
Beet	650 (base 40)	✅	✅	✅	✅
Basil	700 (base 50)	❌	❌	❌	❌
Kale	700 (base 40)	✅	✅	✅	✅
Zucchini	750 (base 50)	❌	❌	❌	❌
Carrot	750 (base 40)	✅	✅	✅	✅
Swiss chard	750 (base 40)	✅	✅	✅	✅
Cucumber	800 (base 50)	❌	❌	❌	❌
Broccoli	900 (base 40)	✅	✅	✅	⚠️
Bean	900 (base 50)	❌	❌	❌	❌
Cabbage	1000 (base 40)	✅	✅	✅	❌
Cauliflower	1000 (base 40)	✅	✅	✅	❌
Sweet corn	1100 (base 50)	❌	❌	❌	❌
Potato	1100 (base 45)	✅	⚠️	❌	❌
Melon	1200 (base 50)	❌	❌	❌	❌
Tomato	1200 (base 50)	❌	❌	❌	❌
Pepper	1300 (base 50)	❌	❌	❌	❌
Onion	1300 (base 45)	⚠️	❌	❌	❌
Winter squash	1300 (base 50)	❌	❌	❌	❌
Pumpkin	1300 (base 50)	❌	❌	❌	❌
Watermelon	1350 (base 50)	❌	❌	❌	❌

Climate normals GDD planning

Compare your season’s typical heat accumulation against crop requirements before first fall frost.

Heat matters more than calendar days Use this when crop maturity depends on warmth, not just frost-free days. Especially useful for warm-season crops and short-season locations.

Best for borderline crops Especially useful for warm-season crops and short-season locations.

Check Crop Maturity and Timing in Juneau

Enter a ZIP / Postal Code in Juneau and your planting date to see whether different crops can typically mature before first fall frost.

ZIP / Postal

Crops

Select one or more crops.

Select Outdoor sow / Transplant date

How the Growing Season Works in Juneau

Juneau is mostly a timing-and-variety season. Reliable results usually come from planting on time, matching maturity to the frost window, and making good use of the remaining summer heat.

Start on time: early establishment is often the biggest controllable factor for warm-season success.
Match crops to the window: dependable harvests usually come from realistic maturity timing, not optimistic timing.
Use late summer well: fast greens, roots, and compact crops are often the best fit for a second round.

Late-summer note: by early August, the remaining heat often tightens quickly. Late plantings tend to work best when they are fast, cold-tolerant, or protected.

Remaining Season Heat in Juneau (Base 50 GDD)

Growing Degree Days (Base 50°F) measure heat accumulation. “Remaining GDD” shows how much usable heat is typically still available from a given date onward in a normal season.

Planting date	Base	Typical GDD still available
May 15	50	678
June 1	50	644
July 1	50	475
August 1	50	247

Use these values to judge whether a crop or variety still has enough heat left after planting. This is especially helpful for later sowings, shorter-maturity choices, and deciding whether a second round is realistic.

How Gardeners Adapt

Experienced gardeners in Juneau usually adjust their timing and crop choices to match how the season actually behaves, not just the calendar.

Planting warm-season crops promptly once frost risk fades.
Using row cover or low tunnels to smooth out temperature swings early and late in the season.
Succession planting fast crops to keep beds productive through summer.
Shifting late plantings toward greens, roots, and other reliable short-season crops.
Watching local conditions closely and adjusting timing year by year.

Juneau Garden Planning Chart

A practical “typical year” for planning. Use it as a baseline, then adjust for microclimates and variety maturity.

Stage	What it usually means
Early season	Start cold-tolerant crops, prep beds, and pay more attention to soil warmth and night temperatures than to the calendar alone.
Main planting	Around May 3, the main planting push usually begins as frost risk fades. Warm-season crops generally perform best when they get established promptly.
Peak growth	This is when water, fertility, spacing, and pest pressure have the biggest effect on final yield.
Late-summer decisions	Late plantings are usually tight, so fast crops and protected spots become much more important.
Finish window	Plan to have frost-sensitive crops mostly wrapped up by October 14. Cooling nights often slow crops before the first real frost arrives.

Typical season length: 164 frost-free days between the median spring and fall frost dates.

Crop Guides for Juneau

Published crop-specific planting guides for Juneau, ordered from best fit to highest risk.

Excellent fit

Beets

Beets are usually one of the easier crops to grow here.

When to Plant Beets in Juneau

Broccoli

Juneau usually gives broccoli enough season that maturity is rarely the hard part.

When to Plant Broccoli in Juneau

Cabbage

Cabbage performs easily here in a typical year.

When to Plant Cabbage in Juneau

Carrots

This crop usually has enough season here that maturity is rarely the hard part.

When to Plant Carrots in Juneau

Cauliflower

Early and mid-season varieties usually fit comfortably here.

When to Plant Cauliflower in Juneau

Kale

Kale is usually one of the easier crops to grow here.

When to Plant Kale in Juneau

Lettuce

Juneau usually gives lettuce enough season that maturity is rarely the hard part.

When to Plant Lettuce in Juneau

Peas

Peas perform easily here in a typical year.

When to Plant Peas in Juneau

Spinach

This crop usually has enough season here that maturity is rarely the hard part.

When to Plant Spinach in Juneau

Strawberries

Very early to mid-season varieties usually fit comfortably here.

When to Plant Strawberries in Juneau

Swiss Chard

Swiss chard is usually one of the easier crops to grow here.

When to Plant Swiss Chard in Juneau

Strong fit

Potatoes

Potatoes are usually a dependable crop choice here.

When to Plant Potatoes in Juneau

Good fit

Onions

Onions are usually a practical crop here with good timing.

When to Plant Onions in Juneau

Borderline

Basil

Basil can work here, but timing and variety choice matter a lot.

When to Plant Basil in Juneau

Cucumbers

Juneau can support cucumbers, though the margin is not generous.

When to Plant Cucumbers in Juneau

Zucchini

This crop stays closer to the edge of the season than easier choices do.

When to Plant Zucchini in Juneau

Risky fit

Beans

Beans are harder to finish well here and usually needs the fastest approach.

When to Plant Beans in Juneau

Melons

Juneau usually gives melons a narrow margin for maturity.

When to Plant Melons in Juneau

Peppers

This is a higher-risk crop here unless the site and timing are especially favorable.

When to Plant Peppers in Juneau

Pumpkin

Growers usually do best with quick varieties and the warmest spots they have.

When to Plant Pumpkin in Juneau

Sweet Corn

Very early varieties usually have the best chance here.

When to Plant Sweet Corn in Juneau

Tomatoes

Tomatoes are harder to finish well here and usually needs the fastest approach.

When to Plant Tomatoes in Juneau

Watermelons

Juneau usually gives watermelons a narrow margin for maturity.

When to Plant Watermelons in Juneau

Winter Squash