Denver Gardening Guide (2026)
High altitude; short season, intense sun.
Quick answer (Denver): Gardeners here work in about a 153-day frost-free window around zone 6. State context: Colorado (zones 3–7). Start warm crops indoors ~6 weeks before the last frost of 05/05.
🌆 Denver microclimate
- High altitude (5b-6a)
- Intense sun, low humidity
- Late spring frosts, short season
What to grow here, by environment
Your Denver planting calendar
Pre-filled with Denver's frost dates. Choose a crop to print your plan.
In this ZIP (typical zone 3–7), last frost ≈ May 5, first frost ≈ Oct 5 (153-day season), your Tomato plan:
Month-by-month (this ZIP, 2026)
| Month | Action |
|---|---|
| Jan | — |
| Feb | — |
| Mar | Start indoors |
| Apr | — |
| May | Sow · Transplant |
| Jun | — |
| Jul | Harvest |
| Aug | — |
| Sep | — |
| Oct | — |
| Nov | — |
| Dec | — |
Start indoors 6 weeks before last frost; transplant after soil warms. Zones 3–13 suitable. Dates are typical; confirm with your county extension and watch the 10-day forecast.
Common pests near Denver
Pre-filled to Colorado. Pick a pest for signs, organic-first treatment, and a printable IPM card.
Grasshopper
Crops that fit zone 6
Vegetables and herbs suited to your metro zone — open any for a state-specific planting card:
Denver year at a glance
A month-by-month rhythm built from Denver's typical frost window (last frost 05/05, first frost 10/05). Dates shift with weather — watch the 10-day forecast before planting tender crops.
| Month | Typical Denver garden work |
|---|---|
| Jan | Plan the season, order seeds, start slow crops (onions from seed) indoors under lights. |
| Feb | Start peppers and early tomatoes indoors ~6-8 weeks before last frost; harden off later crops. |
| Mar | Start warm crops indoors; sow hardy greens (lettuce, spinach, radish) as soil dries. |
| Apr | Around the 05/05 last frost, harden off and transplant warm crops; direct-sow beans and corn. |
| May | Direct-sow the rest of the warm season (tomatoes, peppers, cucumbers, squash); keep transplants watered and mulched. |
| Jun | Keep up with harvests (lettuce, radishes, peas); succession-sow beans and quick greens. |
| Jul | Plant fall brassicas (broccoli, kale) for autumn; keep watering steady through heat. |
| Aug | Start fall greens; sow carrots and beets for late harvest; stay on top of pests. |
| Sep | Plant fall crops of lettuce and spinach; harvest summer crops at peak. |
| Oct | Around the 10/05 first frost, harvest tender crops; plant garlic for next year. |
| Nov | Clean up beds, add compost, cover soil; store root crops; plan cover crops. |
| Dec | Order next year's seeds; review what worked; start spring garden notes. |