Yellowknife, Northwest Territories Garden Guide: Planting Dates, Frost Dates & Growing Season

Growing Season Snapshot

Typical last spring frost May 24

Typical first fall frost September 21

Typical frost-free days 120

GDD left on May 15 (base 50) 681

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.

Yellowknife Planting Calendar

A practical guide to when planting usually works in Yellowknife. 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 26 – May 10	direct sow	Little Marvel	Excellent fit
Spinach	April 26 – May 10	direct sow	Space	Excellent fit
Kale	April 30 – May 20	direct sow / transplant	Winterbor	Excellent fit
Beets	May 3 – May 17	direct sow	Detroit Dark Red	Excellent fit
Carrots	May 3 – May 17	direct sow	Bolero	Excellent fit
Lettuce	May 3 – May 17	direct sow / transplant	Buttercrunch	Excellent fit
Strawberries	May 3 – May 17	plant crowns / transplants	Seascape	Excellent fit
Onions	May 3 – May 17	sets / transplants	Walla Walla	Borderline
Swiss Chard	May 4 – May 24	direct sow / transplant	Bright Lights	Excellent fit
Broccoli	May 10 – May 24	transplant	Packman	Strong fit
Cabbage	May 10 – May 24	transplant	Stonehead	Strong fit
Cauliflower	May 10 – May 24	transplant	Snow Crown	Strong fit
Potatoes	May 10 – May 24	plant seed potatoes	Dark Red Norland	Good fit
Main warm-season window Crops that usually do best once frost risk fades and the season starts opening up more fully.
Beans	May 24 – June 7	direct sow	Provider	Risky fit
Sweet Corn	May 29 – June 8	direct sow	Yukon Chief	Risky fit
Basil	June 2 – June 12	direct sow / transplant	Prospera	Borderline
Cucumbers	June 2 – June 12	direct sow / transplant	Cool Breeze	Borderline
Zucchini	June 2 – June 12	direct sow / transplant	Dunja	Borderline
Melons	June 2 – June 12	direct sow / transplant	Minnesota Midget	Risky fit
Pumpkin	June 2 – June 12	direct sow / transplant	Small Sugar	Risky fit
Tomatoes	June 2 – June 12	transplant	Stupice	Risky fit
Watermelons	June 2 – June 12	direct sow / transplant	Sugar Baby	Risky fit
Winter Squash	June 2 – June 12	direct sow / transplant	Delicata	Risky fit
Peppers	June 9 – June 19	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 Yellowknife — 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 Yellowknife. 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 Yellowknife

Enter a ZIP / Postal Code in Yellowknife 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 Yellowknife

Yellowknife 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 Yellowknife (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	681
June 1	50	681
July 1	50	552
August 1	50	220

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 Yellowknife 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.

Yellowknife 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 24, 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 September 21. Cooling nights often slow crops before the first real frost arrives.

Typical season length: 120 frost-free days between the median spring and fall frost dates.

Crop Guides for Yellowknife

Published crop-specific planting guides for Yellowknife, 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 Yellowknife

Carrots

Yellowknife usually gives carrots enough season that maturity is rarely the hard part.

When to Plant Carrots in Yellowknife

Kale

Kale performs easily here in a typical year.

When to Plant Kale in Yellowknife

Lettuce

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

When to Plant Lettuce in Yellowknife

Peas

Very early to late varieties usually fit comfortably here.

When to Plant Peas in Yellowknife

Spinach

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

When to Plant Spinach in Yellowknife

Strawberries

Yellowknife usually gives strawberries enough season that maturity is rarely the hard part.

When to Plant Strawberries in Yellowknife

Swiss Chard

Swiss chard performs easily here in a typical year.

When to Plant Swiss Chard in Yellowknife

Strong fit

Broccoli

Broccoli is usually a dependable crop choice here.

When to Plant Broccoli in Yellowknife

Cabbage

Yellowknife usually gives cabbage enough season for reliable maturity.

When to Plant Cabbage in Yellowknife

Cauliflower

Cauliflower performs well here when planted on time.

When to Plant Cauliflower in Yellowknife

Good fit

Potatoes

Potatoes are usually a practical crop here with good timing.

When to Plant Potatoes in Yellowknife

Borderline

Basil

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

When to Plant Basil in Yellowknife

Cucumbers

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

When to Plant Cucumbers in Yellowknife

Onions

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

When to Plant Onions in Yellowknife

Zucchini

Earlier varieties and warmer spots usually improve the odds here.

When to Plant Zucchini in Yellowknife

Risky fit

Beans

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

When to Plant Beans in Yellowknife

Melons

Yellowknife usually gives melons a narrow margin for maturity.

When to Plant Melons in Yellowknife

Peppers

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

When to Plant Peppers in Yellowknife

Pumpkin

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

When to Plant Pumpkin in Yellowknife

Sweet Corn

Very early varieties usually have the best chance here.

When to Plant Sweet Corn in Yellowknife

Tomatoes

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

When to Plant Tomatoes in Yellowknife

Watermelons

Yellowknife usually gives watermelons a narrow margin for maturity.

When to Plant Watermelons in Yellowknife

Winter Squash