When to plant Astilbe in Putnam County, IN
In Putnam County, Astilbe is a single-season spring crop — there's no second fall window. Plant April 21–May 5 for an 70–100-day harvest, finishing well before the October 21 first frost.
When to Plant Astilbe in Putnam County, IN
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.
Putnam County, Indiana is in USDA Zone 6a. The average last spring frost is April 14 and the first fall frost is October 21, giving you a growing season of approximately 190 days.
At an elevation of 670 feet, Putnam County receives approximately 31.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Astilbe during the growing season.
Putnam County Soil Profile
Soil Type
Silt Loam
Soil pH
6.0-7.0
Drainage
Well Drained
Astilbe Planting Timeline — Putnam County, IN
Astilbe Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 10 | Feb 10 – Feb 24 |
| Transplant Outdoors | April 21 | Apr 21 – May 5 |
| Bloom | June 30 | Jun 30 – Sep 8 |
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 | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | — |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Partial Shade (3-6 hours)
💧 Water
High — keep soil consistently moist
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–8 · Your soil: N/A
🗺️ USDA Zone
Zone 6a
📆 Growing Season
190 days in Putnam County
Growing Tips for Putnam County
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 Putnam County, IN?
Putnam County is in Zone 6a with an average last frost of April 14. Plan your Astilbe planting based on this frost date — see the calendar above for exact timing.
What planting zone is Putnam County, IN?
Putnam County, Indiana is in USDA Hardiness Zone 6a. The average last spring frost is April 14 and first fall frost is October 21.
When should I plant Astilbe in Putnam County, IN?
In Putnam County, IN, plant Astilbe after the last frost (around April 14) and before the first frost (around October 21). Best results when soil holds above 50°F.
What growing zone is Putnam County, IN for Astilbe?
Putnam 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 Putnam County's climate?
Yes — Astilbe grows well in Putnam County's temperate climate. Putnam County averages a 190-day frost-free season, with last frost around April 14 and first frost around October 21.
Your Putnam County Garden Planner — Free
A 22-page printable planner built for Putnam 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.