When to Plant Yarrow in Denver County, CO
Yarrow is a drought-tolerant perennial herb with feathery foliage and flat-topped flower clusters in white, yellow, pink, or red. It attracts beneficial insects and is used in herbal medicine.
Denver County, Colorado is in USDA Zone 5b. The average last spring frost is May 14 and the first fall frost is September 26, giving you a growing season of approximately 135 days.
At an elevation of 6,818 feet, Denver County receives approximately 20.5 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Yarrow during the growing season.
Denver County Soil Profile
Soil Type
Loam
Soil pH
6.4-7.8
Drainage
Well Drained
Plant Planting Risk Windows
Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.
Soil Compatibility in Denver County
How your county's soil matches Yarrow's growing requirements.
Soil pH
Your soil pH (6.4–7.8) is more alkaline than Yarrow prefers (5.5–7.0). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Denver County is excellent for Yarrow — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.2%). Annual compost additions will help Yarrow.
How to Plant Yarrow
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Yarrow Planting Timeline — Denver County, CO
Yarrow Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | May 21 | May 21 – Jun 4 |
| Harvest | August 20 | Aug 20 – Nov 5 |
Plant 0.5" deep · 8" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | — |
| August | Harvest |
| September | Harvest |
| October | Harvest |
| November | Harvest |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
90–120 days
🧪 Soil pH
Needs 5.5–7 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5b
📆 Growing Season
135 days in Denver County
Growing Tips for Yarrow in Denver County
Direct sow Yarrow outdoors after May 14 in Denver County when soil has warmed and frost danger has passed.
Common pests for Yarrow in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
Denver County receives only 20" of rain annually. Yarrow needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow or start from divisions. Yarrow thrives in poor soil and is very drought-tolerant. Deadhead to encourage reblooming. Divide clumps every 3 years.
Companion Planting
Good Companions
Level Up Your Garden
Yarrow in Other Locations
Frequently Asked Questions
When should I plant Yarrow in Denver County, CO?
Denver County is in Zone 5b with an average last frost of May 14. Plan your Yarrow planting based on this frost date — see the calendar above for exact timing.
What planting zone is Denver County, CO?
Denver County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 14 and first fall frost is September 26.
Plan Your Garden with Confidence
Get our free Garden Planner — designed to help Denver County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.
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