When to Plant Astilbe in Pennsylvania

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.

Pennsylvania spans USDA hardiness zones 5b, 6a, 6b, 7a, 7b (with planting data available), so planting dates vary by your location within the state. Click your zone below for the most accurate dates.

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Click your county for exact Astilbe planting dates based on your local frost dates.

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Astilbe Planting Calendar for Pennsylvania

▸ Zone 5b ~178 day growing season · Full guide →

Last frost: April 18 · First frost: October 13 · 178 day season

Activity	When	Date Range
Start Indoors	February 14	Feb 14 – Feb 28
Transplant Outdoors	May 2	May 2 – May 16
Bloom	July 18	Jul 18 – Sep 26

▸ Zone 6a ~193 day growing season · Full guide →

Last frost: April 10 · First frost: October 20 · 193 day season

Activity	When	Date Range
Start Indoors	February 6	Feb 6 – Feb 20
Transplant Outdoors	April 17	Apr 17 – May 1
Bloom	June 26	Jun 26 – Sep 4

▸ Zone 6b ~205 day growing season · Full guide →

Last frost: April 3 · First frost: October 25 · 205 day season

Activity	When	Date Range
Start Indoors	January 30	Jan 30 – Feb 13
Transplant Outdoors	April 10	Apr 10 – Apr 24
Bloom	June 19	Jun 19 – Aug 28

▸ Zone 7a ~221 day growing season · Full guide →

Last frost: March 25 · First frost: November 1 · 221 day season

Activity	When	Date Range
Start Indoors	January 21	Jan 21 – Feb 4
Transplant Outdoors	April 1	Apr 1 – Apr 15
Bloom	June 10	Jun 10 – Aug 5

▸ Zone 7b ~235 day growing season · Full guide →

Last frost: March 18 · First frost: November 8 · 235 day season

Activity	When	Date Range
Start Indoors	January 14	Jan 14 – Jan 28
Transplant Outdoors	March 25	Mar 25 – Apr 8
Bloom	June 3	Jun 3 – Jul 29

Growing Tips for Pennsylvania

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.

Astilbe in Other States

Frequently Asked Questions

When should I plant Astilbe in Pennsylvania?

Planting dates for Astilbe in Pennsylvania depend on your USDA zone. Pennsylvania spans zones 5b, 6a, 6b, 7a, 7b. Check the planting calendar above for your specific zone's frost dates and planting windows.

What zone is Pennsylvania for planting?

Pennsylvania contains USDA hardiness zones 5b, 6a, 6b, 7a, 7b. Your specific zone depends on your location within the state — northern and higher-elevation areas are in colder zones, while southern and coastal areas are warmer.

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