When to plant Astilbe in Teller County, CO
In Teller County, Astilbe is a spring-only crop. Plant May 25–June 8 once soil hits 50°F.
When to Plant Astilbe in Teller County, CO
Your July planting checklist for Teller County, Colorado
Your garden in Teller County, Colorado is working on a schedule, even when you're not. Here's where you should be this July.
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Start astilbe indoors
Give them 6–8 weeks indoors before the last frost and you'll transplant into warm soil with seedlings that are already leaping.
August will be here before you know it — start on
- First harvests: astilbe
Astilbe (Astilbe x arendsii) is a premier perennial for shaded, moist gardens, producing feathery plume-like flower spikes in shades of pink, red, white, and lavender above deeply cut, ferny foliage. Originating in Asia and naturalized in shade gardens worldwide, astilbe thrives where many sun-lovers fail: under trees, beside water features, or in persistently moist woodland borders. The dried flower plumes remain attractive through fall and winter. Different cultivars extend the bloom season from early summer through early fall when several varieties are combined.
Teller County, Colorado is in USDA Zone 5b. The average last spring frost is May 11 and the first fall frost is October 6, giving you a growing season of approximately 148 days.
At an elevation of 6,538 feet, Teller County receives approximately 19.5 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Astilbe to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Astilbe successfully. Mulch heavily to conserve soil moisture.
Teller County Soil Profile
Soil Type
Loam
Soil pH
6.4-8.1
Drainage
Well Drained
Astilbe 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 Teller County
How your county's soil matches Astilbe's growing requirements.
Soil pH
Your soil pH (6.4–8.1) overlaps with Astilbe's range (6.0–8.0), though not a perfect match.
Soil Texture
The loam soil in Teller County is excellent for Astilbe — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Astilbe.
How to Plant Astilbe
Succession Planting Astilbe
Sow every 8 weeks. Last sowing by Jun 28 to harvest before frost.
Astilbe Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Astilbe
Astilbe needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.
| Month | Astilbe Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1.3" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 1.9" | 0" | ❄️ Dormant |
| Apr | — | 2.1" | 0" | ❄️ Dormant |
| May | 6.5" | 2.4" | 4.1" | 🚿 Regular watering |
| Jun | 6.5" | 1.3" | 5.2" | 🚿 Regular watering |
| Jul | 6.5" | 1.5" | 5" | 🚿 Regular watering |
| Aug | 6.5" | 1.7" | 4.8" | 🚿 Regular watering |
| Sep | 6.5" | 1.7" | 4.8" | 🚿 Regular watering |
| Oct | 6.5" | 1.9" | 4.6" | 🚿 Regular watering |
| Nov | — | 1.3" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Oct in Teller County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Astilbe Heat Requirements (GDD)
What are Growing Degree Days (GDD)?
Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.
Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.
Astilbe Planting Timeline — Teller County, CO
Astilbe Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 9 | Mar 9 – Mar 23 |
| Transplant Outdoors | May 25 | May 25 – Jun 8 |
| Bloom | August 10 | Aug 10 – Oct 19 |
Plant 1.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors |
| June | Transplant Outdoors |
| July | — |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 2-3 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–8 · Your soil: acceptable
🗺️ USDA Zone
Zone 5b
📆 Growing Season
148 days in Teller County
Growing Tips for Astilbe in Teller County
Direct sow Astilbe outdoors after May 11 in Teller County when soil has warmed and frost danger has passed.
Teller County receives only 20" of rain annually. Astilbe needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant bare-root crowns in spring as soon as the ground is workable, setting eyes 1–2 inches below soil level. Fall planting (Zones 4+) is equally effective. Consistent moisture is non-negotiable — astilbe will wilt and scorch in drought. Amend with generous compost to improve moisture retention. Partial shade (morning sun, afternoon shade) is ideal; deep shade reduces bloom but foliage remains. Fertilize lightly in spring with a balanced slow-release granular. Divide every 3–5 years in early spring as clumps become congested. Leave plumes standing through winter for ornamental interest and wildlife value. Year 2+ plants produce the fullest bloom spikes; first-year crowns may flower lightly or not at all.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Astilbe in Other Locations
Frequently Asked Questions
When should I plant Astilbe in Teller County, CO?
Teller County is in Zone 5b with an average last frost of May 11. Plan your Astilbe planting based on this frost date — see the calendar above for exact timing.
What planting zone is Teller County, CO?
Teller County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 11 and first fall frost is October 6.
When should I plant Astilbe in Teller County, CO?
In Teller County, CO, plant Astilbe after the last frost (around May 11) and before the first frost (around October 6). Best results when soil holds above 50°F.
What growing zone is Teller County, CO for Astilbe?
Teller County sits in USDA Zone 5b. Astilbe grows reliably in zones 3a through 8b, so it's a good fit here.
Can Astilbe grow in Teller County's climate?
Yes — Astilbe grows well in Teller County's temperate climate. Teller County averages a 148-day frost-free season, with last frost around May 11 and first frost around October 6.
Your Teller County Garden Planner — Free
A 22-page printable planner built for Teller County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.