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When to Plant Astilbe in Daggett County, UT

Daggett County, Utah Zone 5b June

This month in Daggett County, Utah

A quick June briefing for Daggett County, Utah gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 13
Avg. first frost October 1
Soil temp (4") 41°F
Watering Critical
Pest pressure High
Daylight 14.9 hrs
July prep starts now
  • Starting indoors: astilbe

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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.

Daggett County, Utah is in USDA Zone 5b. The average last spring frost is May 13 and the first fall frost is October 1, giving you a growing season of approximately 141 days.

At an elevation of 7,540 feet, Daggett County receives approximately 14.6 inches of rainfall annually with predominantly loam soil. Summer highs average 82°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.

Perennial Blooms in Summer Pollinator-friendly Deer-resistant Good for cutting
Daggett County, UT (Zone 5b) Short season
141 days
Last Spring Frost May 13
141 growing days
First Fall Frost October 1

Daggett County Soil Profile

Soil Type

Loam

Soil pH

6.8-8.4

Drainage

Well Drained

Astilbe Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 2 Transplant: May 18 🌸 Bloom: Aug 3 – Oct 12
Recommended (50%) ✗ May not fit
Start indoors: Mar 11 Transplant: May 27 🌸 Bloom: Aug 12 – Oct 21
Safe Start (90%) ✗ May not fit
Start indoors: Apr 8 Transplant: Jun 24 🌸 Bloom: Sep 9 – Nov 18

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 Daggett County

How your county's soil matches Astilbe's growing requirements.

Soil pH

Your soil pH (6.8–8.4) overlaps with Astilbe's range (6.0–8.0), though not a perfect match.

Soil Texture

The loam soil in Daggett 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

1.5"
Planting Depth
18"
Between Plants
24"
Between Rows

Succession Planting Astilbe

2
successive plantings in your 141-day season

Sow every 8 weeks. Last sowing by Jun 23 to harvest before frost.

Astilbe Water Budget

Plant needs
1.5″/week
Rainfall provides
0.4″/week
You supply
1.3″/week
Watering frequency 2-3 times/week
Season total 1,604 gal / 100 sq ft
Drought risk

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 1.2" 0" ❄️ Dormant
Feb 0.9" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.6" 0" ❄️ Dormant
May 6.5" 1.7" 4.8" 🚿 Regular watering
Jun 6.5" 0.9" 5.6" 🚿 Regular watering
Jul 6.5" 1.3" 5.2" 🚿 Regular watering
Aug 6.5" 1.3" 5.2" 🚿 Regular watering
Sep 6.5" 1.4" 5.1" 🚿 Regular watering
Oct 6.5" 1.5" 5" 🚿 Regular watering
Nov 1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Daggett 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 needs ~978 GDD — county provides 1,621 GDD Excellent fit

Astilbe Planting Timeline — Daggett County, UT

Astilbe Planting Calendar

Activity When Date Range
Start Indoors March 11 Mar 11 – Mar 25
Transplant Outdoors May 27 May 27 – Jun 10
Bloom August 12 Aug 12 – Oct 21

Plant 1.5" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
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

141 days in Daggett County

Growing Tips for Astilbe in Daggett County

Direct sow Astilbe outdoors after May 13 in Daggett County when soil has warmed and frost danger has passed.

Daggett County receives only 15" 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 →

Frequently Asked Questions

When should I plant Astilbe in Daggett County, UT?

Daggett County is in Zone 5b with an average last frost of May 13. Plan your Astilbe planting based on this frost date — see the calendar above for exact timing.

What planting zone is Daggett County, UT?

Daggett County, Utah is in USDA Hardiness Zone 5b. The average last spring frost is May 13 and first fall frost is October 1.

🌱

Your Daggett County Garden Planner — Free

A 22-page printable planner built for Daggett 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.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Daggett County, UT. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.