🧅 Can I Plant Leek in Denver, CO?

2026 planting guide for Zone 5b · Last frost ~May 7 · Growing season ~153 days

⏳ WAIT — Too late to harvest before first frost (~Nov 2)

Leek needs at least 100 days to harvest, but there are only ~94 days before the average first fall frost around Nov 2. Wait until next spring for best results.

Planting window: Feb 10 – Feb 24 (next spring)
Skip this season. Plan to start leek again around Feb 10 next spring.
Live result based on current forecast for Denver, CO · Updates every 6 hours
USDA Zone
5b
Last Spring Frost
~May 7
First Fall Frost
October 7
Growing Season
~153 days
Ideal Temp for Leek
45–75°F
Frost Risk
✅ Tolerant

Growing Leek in Denver

Denver's Zone 5b location at 5,280 feet elevation means gardeners face late spring frosts (sometimes into May) and early fall frosts (as early as late September). The intense high-altitude sun and dry air accelerate both plant growth and water loss. Row covers, raised beds, and careful timing are key to Denver gardening success.

In Denver (last frost around May 7), leek can go out around April — approximately 4 weeks before the last expected frost, making it an early-season opportunity. Starting seeds indoors 12 weeks before the last frost date gives you a significant head start.

Leek thrives between 45°F and 75°F. It tolerates temperatures as low as 28°F, making it a candidate for early spring planting before the last frost date. Expect 100–130 days from transplant to first harvest. Long-season crop. Start indoors early. Very cold hardy.

Frequently Asked Questions

When can I plant leek in Denver, CO?

In Denver (last frost around May 7), leek can go out around April — approximately 4 weeks before the last expected frost, making it an early-season opportunity. For best results, start seeds indoors 12 weeks before that — giving you strong transplants ready to go out at the right time.

What is the USDA hardiness zone for Denver?

Denver, CO is in USDA Plant Hardiness Zone 5b. The last expected spring frost is around May 7, and the first fall frost arrives around October 7. This zone classification helps you understand which perennials survive winter and when annual vegetables can safely go outdoors.

Is it safe to plant leek outside in Denver right now?

That depends on the current weather forecast. Leek needs temperatures above 28°F (ideally 45–75°F) to thrive. CanIPlant checks your real 7-day forecast and any active frost alerts to give you a live YES, NO, or WAIT answer — just enter your ZIP code.

Can I grow leek in Denver 2026?

Yes — Leek grows well in Denver, CO. With a Zone 5b climate and a growing season of ~153 days, Denver is well-suited for cool-season crops like leek. As a frost-tolerant crop, leek can even go out a few weeks before the last frost date.

Grow Leek in Other Cities

New York, NYLos Angeles, CAChicago, ILHouston, TXPhoenix, AZPhiladelphia, PASan Antonio, TXSan Diego, CA

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