When to plant Astilbe in Edgar County, IL
Plant Astilbe in Edgar County during the brief April 25–May 9 window. With 182 frost-free days, fall plantings can't mature before October 17.
When to Plant Astilbe in Edgar County, IL
This month in Edgar County, Illinois
Each item below is timed to Edgar County, Illinois's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Collect astilbe at their peak
Check every 1–2 days. Many of these get tough or go to seed if you wait too long.
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.
Edgar County, Illinois is in USDA Zone 6a. The average last spring frost is April 18 and the first fall frost is October 17, giving you a growing season of approximately 182 days.
At an elevation of 1,272 feet, Edgar County receives approximately 41.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Astilbe to ensure they mature before fall.
Edgar County Soil Profile
Soil Type
Silt Loam
Soil pH
5.9-6.8
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 Edgar County
How your county's soil matches Astilbe's growing requirements.
Soil pH
Your soil pH (5.9–6.8) overlaps with Astilbe's range (6.0–8.0), though not a perfect match.
Soil Texture
The silt loam soil in Edgar County is excellent for Astilbe — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.3%) — Astilbe will thrive.
How to Plant Astilbe
Succession Planting Astilbe
Sow every 8 weeks. Last sowing by Jul 09 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 | — | 1.6" | 0" | ❄️ Dormant |
| Feb | — | 1.9" | 0" | ❄️ Dormant |
| Mar | — | 2.8" | 0" | ❄️ Dormant |
| Apr | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| May | 6.5" | 4.8" | 1.7" | 💧 Light watering |
| Jun | 6.5" | 5.5" | 1" | 💧 Light watering |
| Jul | 6.5" | 4.9" | 1.6" | 💧 Light watering |
| Aug | 6.5" | 3.8" | 2.7" | 💧 Light watering |
| Sep | 6.5" | 3.9" | 2.6" | 💧 Light watering |
| Oct | 6.5" | 3.3" | 3.2" | 💧 Light watering |
| Nov | — | 2.9" | 0" | ❄️ Dormant |
| Dec | — | 2.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Edgar 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 — Edgar County, IL
Astilbe Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 14 | Feb 14 – Feb 28 |
| Transplant Outdoors | April 25 | Apr 25 – May 9 |
| Bloom | July 4 | Jul 4 – Sep 12 |
Plant 1.5" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors |
| May | Transplant Outdoors |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
1.5"/week · 1-2 times/week
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–8 · Your soil: acceptable
🗺️ USDA Zone
Zone 6a
📆 Growing Season
182 days in Edgar County
Growing Tips for Astilbe in Edgar County
Direct sow Astilbe outdoors after April 18 in Edgar County when soil has warmed and frost danger has passed.
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 Edgar County, IL?
Edgar County is in Zone 6a with an average last frost of April 18. Plan your Astilbe planting based on this frost date — see the calendar above for exact timing.
What planting zone is Edgar County, IL?
Edgar County, Illinois is in USDA Hardiness Zone 6a. The average last spring frost is April 18 and first fall frost is October 17.
When should I plant Astilbe in Edgar County, IL?
In Edgar County, IL, plant Astilbe after the last frost (around April 18) and before the first frost (around October 17). Best results when soil holds above 50°F.
What growing zone is Edgar County, IL for Astilbe?
Edgar County sits in USDA Zone 6a. Astilbe grows reliably in zones 3a through 8b, so it's a good fit here.
Can Astilbe grow in Edgar County's climate?
Yes — Astilbe grows well in Edgar County's temperate climate. Edgar County averages a 182-day frost-free season, with last frost around April 18 and first frost around October 17.
Your Edgar County Garden Planner — Free
A 22-page printable planner built for Edgar County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.