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When to Plant Hostas in Somerset County, PA

Somerset County, Pennsylvania Zone 6a June

This month in Somerset County, Pennsylvania

June rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Somerset County, Pennsylvania.

Avg. last frost May 6
Avg. first frost October 12
Soil temp (4") 71°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
Before July arrives, get these ready
  • Starting indoors: hostas
  • First harvests: hostas

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Hostas (Hosta spp.) are the undisputed kings of the shade garden, grown primarily for their spectacular mounded foliage in shades of deep green, blue-green, gold, and variegated combinations. Originating in East Asia (Japan, China, Korea), hostas form dense, long-lived clumps that reliably return year after year with minimal care. In summer, tall scapes of lavender or white tubular flowers rise above the foliage — some cultivars (notably H. plantaginea hybrids) are notably fragrant. Extremely adaptable in moist, well-drained soil with consistent shade to part shade.

Somerset County, Pennsylvania is in USDA Zone 6a. The average last spring frost is May 6 and the first fall frost is October 12, giving you a growing season of approximately 159 days.

At an elevation of 60 feet, Somerset County receives approximately 41.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 84°F, so choose short-season varieties of Hostas to ensure they mature before fall.

Perennial Blooms in Summer Pollinator-friendly
Somerset County, PA (Zone 6a) Moderate season
159 days
Last Spring Frost May 6
159 growing days
First Fall Frost October 12

Somerset County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.2

Drainage

Well Drained

Hostas Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 16 Transplant: May 4 🌸 Bloom: Jul 20 – Nov 2
Recommended (50%) ✗ May not fit
Start indoors: Feb 25 Transplant: May 13 🌸 Bloom: Jul 29 – Nov 11
Safe Start (90%) ✗ May not fit
Start indoors: Mar 13 Transplant: May 29 🌸 Bloom: Aug 14 – Nov 27

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 Somerset County

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

Soil pH

Your soil pH (5.1–6.2) is more acidic than Hostas prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

The silt loam soil in Somerset County is excellent for Hostas — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (3.0%). Annual compost additions will help Hostas.

How to Plant Hostas

1"
Planting Depth
24"
Between Plants
30"
Between Rows

Succession Planting Hostas

3
successive plantings in your 159-day season

Sow every 6.9 weeks. Last sowing by Jul 14 to harvest before frost.

Hostas Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Hostas

Hostas needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Hostas Needs Rainfall You Supplement Action
Jan 3.1" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 3.8" 0" ❄️ Dormant
Apr 3.1" 0" ❄️ Dormant
May 4.3" 3.2" 1.1" 💧 Light watering
Jun 4.3" 4.1" 0.2" 💧 Light watering
Jul 4.3" 4.5" 0" ✅ Rainfall sufficient
Aug 4.3" 3.3" 1" 💧 Light watering
Sep 4.3" 3.7" 0.6" 💧 Light watering
Oct 4.3" 3.7" 0.6" 💧 Light watering
Nov 3" 0" ❄️ Dormant
Dec 2.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Somerset County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Hostas 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.

Hostas needs ~975 GDD — county provides 2,067 GDD Excellent fit

Hostas Planting Timeline — Somerset County, PA

Hostas Planting Calendar

Activity When Date Range
Start Indoors February 25 Feb 25 – Mar 11
Transplant Outdoors May 13 May 13 – May 27
Bloom July 29 Jul 29 – Nov 11

Plant 1" deep · 24" apart · Rows 30" apart

Month-by-Month Timeline

MonthActivities
January
February Start Indoors
March Start Indoors
April
May Transplant Outdoors
June
July Bloom
August Bloom
September Bloom
October Bloom
November Bloom
December

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 6a

📆 Growing Season

159 days in Somerset County

Growing Tips for Hostas in Somerset County

Direct sow Hostas outdoors after May 06 in Somerset County when soil has warmed and frost danger has passed.

General growing tips

Plant bare-root crowns or divisions in early spring just as new growth emerges, or in fall at least 6 weeks before hard freeze. Choose a site with morning sun and afternoon shade in Zones 6+; deeper shade is acceptable but reduces vigor and bloom. Keep consistently moist but never waterlogged. Apply a 2–3 inch mulch layer to conserve moisture and suppress weeds. Slugs are the primary pest — use iron phosphate bait if damage is significant. Deer will browse hostas heavily in most regions; protect with fencing or repellents. Divide every 3–5 years in spring to rejuvenate. Fall planting (Zones 4+) is equally effective as spring planting when soil stays workable. Year 2+ plants reach full size and flower most reliably; first-year divisions may produce limited flower spikes.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Hostas in Somerset County, PA?

Somerset County is in Zone 6a with an average last frost of May 6. Plan your Hostas planting based on this frost date — see the calendar above for exact timing.

What planting zone is Somerset County, PA?

Somerset County, Pennsylvania is in USDA Hardiness Zone 6a. The average last spring frost is May 6 and first fall frost is October 12.

🌱

Your Somerset County Garden Planner — Free

A 22-page printable planner built for Somerset 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.

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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 Somerset County, PA. 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.