When to Plant Garlic in Colorado
Plant in fall, harvest in summer. Garlic is one of the most rewarding crops for the patient gardener.
The Short Answer
Colorado Frost Dates
Your planting dates depend on which part of Colorado you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Front Range (Denver) | 5a, 5b, 6a | May 1 - May 15 | Sep 25 - Oct 10 |
| Western Slope | 4b, 5a, 5b, 6a | May 10 - Jun 1 | Sep 15 - Oct 5 |
| Mountain Regions | 3a, 3b, 4a, 4b | Jun 1 - Jun 20 | Aug 25 - Sep 15 |
Garlic Planting Schedule for Colorado
Front Range (Denver) (Zones 5a, 5b, 6a)
Average last frost: May 1 - May 15 · Average first frost: Sep 25 - Oct 10
Western Slope (Zones 4b, 5a, 5b, 6a)
Average last frost: May 10 - Jun 1 · Average first frost: Sep 15 - Oct 5
Mountain Regions (Zones 3a, 3b, 4a, 4b)
Average last frost: Jun 1 - Jun 20 · Average first frost: Aug 25 - Sep 15
Growing Garlic in Colorado
Garlic in Colorado's Climate
Your cold winters are garlic's secret weapon. Hardneck varieties — the type with the best flavor and those coveted scapes — actually require prolonged cold (vernalization) to form proper bulbs. Plant cloves in October, 6 weeks before the ground freezes, and mulch heavily. The cloves root before winter, sleep under snow, and explode with growth in spring. Northern gardeners grow the best garlic in America because the cold is an asset, not a limitation.
Soil Considerations for Colorado
Alkaline clay soils common along Front Range. Rocky, thin soils in mountains. Amend heavily with compost and sulfur to lower pH. Loose, well-drained soil is especially important for garlic since the edible portion grows underground. If your soil is heavy clay, consider raised beds.
Colorado Climate & Growing Season
High altitude means intense sun but cool nights. Low humidity. Hail risk in late spring. Short but intense growing season at elevation. Garlic can handle frost well, which is an advantage in Colorado's climate. You can push planting dates earlier in spring and extend into fall.
Growing season length varies across Colorado: Front Range (Denver) (5a, 5b, 6a) has a last frost around May 1 - May 15, while Mountain Regions (3a, 3b, 4a, 4b) sees frost end around Jun 1 - Jun 20. This difference matters for garlic — adjust your planting dates to match your specific region.
Growing Tips
Plant individual cloves pointy-side up in fall, 4-6 weeks before ground freezes. Mulch heavily. Harvest when lower leaves brown.
Companion Planting
Plant garlic alongside these companions for better growth:
Keep garlic away from:
The Bottom Line
Last reviewed: March 29, 2026