When to Plant Astilbe in Sublette County, WY
Your June gardening checklist
A quick June briefing for Sublette County, Wyoming gardeners — what's urgent, what's next, and what can wait.
Coming up in July — start thinking about
- Transplants going out: 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.
Sublette County, Wyoming is in USDA Zone 4b. The average last spring frost is June 22 and the first fall frost is August 24, giving you a growing season of approximately 63 days.
At an elevation of 5,005 feet, Sublette County receives approximately 22.8 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Astilbe to ensure they mature before fall.
Sublette County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.8
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 Sublette County
How your county's soil matches Astilbe's growing requirements.
Soil pH
Your soil pH (6.7–7.8) is within Astilbe's preferred range (6.0–8.0).
Soil Texture
The loam soil in Sublette County is excellent for Astilbe — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.2%). Annual compost additions will help Astilbe.
How to Plant Astilbe
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 | — | 1.8" | 0" | ❄️ Dormant |
| Feb | — | 1.5" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 2.6" | 0" | ❄️ Dormant |
| May | — | 2.5" | 0" | ❄️ Dormant |
| Jun | 6.5" | 1.5" | 5" | 🚿 Regular watering |
| Jul | 6.5" | 2.2" | 4.3" | 🚿 Regular watering |
| Aug | 6.5" | 2.1" | 4.4" | 🚿 Regular watering |
| Sep | — | 1.7" | 0" | ❄️ Dormant |
| Oct | — | 2" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.4" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Aug in Sublette 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 — Sublette County, WY
Astilbe Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 13 | Apr 13 – Apr 27 |
| Transplant Outdoors | July 6 | Jul 6 – Jul 20 |
| Bloom | September 28 | Sep 28 – Nov 23 |
Plant 1.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | — |
| June | — |
| July | Transplant Outdoors |
| August | — |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · Natural rainfall sufficient
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–8 · Your soil: ideal
🗺️ USDA Zone
Zone 4b
📆 Growing Season
63 days in Sublette County
Growing Tips for Astilbe in Sublette County
Direct sow Astilbe outdoors after June 22 in Sublette County when soil has warmed and frost danger has passed.
Your 63.0-day growing season in Sublette County is tight for Astilbe (70.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.
Sublette County receives only 23" 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 Sublette County, WY?
Sublette County is in Zone 4b with an average last frost of June 22. Plan your Astilbe planting based on this frost date — see the calendar above for exact timing.
What planting zone is Sublette County, WY?
Sublette County, Wyoming is in USDA Hardiness Zone 4b. The average last spring frost is June 22 and first fall frost is August 24.
Your Sublette County Garden Planner — Free
A 22-page printable planner built for Sublette County (Zone 4b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.