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When to Plant Mulberries in Grays Harbor County, WA

Grays Harbor County, Washington Zone 8b May

May in Grays Harbor County, Washington — your action list

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Grays Harbor County, Washington.

Avg. last frost April 27
Avg. first frost October 23
Soil temp (4") 69°F
Watering High
Pest pressure High
Daylight 14.9 hrs
  1. Set out mulberries seedlings

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

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Mulberries are fast-growing, long-lived trees that produce abundant sweet-tart berries over an extended harvest period. The berries resemble elongated blackberries.

Grays Harbor County, Washington is in USDA Zone 8b. The average last spring frost is April 27 and the first fall frost is October 23, giving you a growing season of approximately 179 days.

At an elevation of 65 feet, Grays Harbor County receives approximately 39.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Mulberries during the growing season.

Grays Harbor County, WA (Zone 8b) Moderate season
179 days
Last Spring Frost April 27
179 growing days
First Fall Frost October 23
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Grays Harbor County Soil Profile

Soil Type

Silt Loam

Soil pH

5.5-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: May 5
Recommended (50%) ✓ Fits season
Transplant: May 18
Safe Start (90%) ✓ Fits season
Transplant: Jun 2

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 Grays Harbor County

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

Soil pH

Your soil pH (5.5–6.7) is within Mulberries's preferred range (5.5–7.0).

Soil Texture

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

Organic Matter

Organic matter is excellent (5.5%) — Mulberries will thrive.

How to Plant Mulberries

120"
Between Plants
144"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 120 gal / 100 sq ft

Monthly Watering Guide for Mulberries

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

Month Mulberries Needs Rainfall You Supplement Action
Jan 5.9" 0" ❄️ Dormant
Feb 4.3" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 4.3" 3.3" 1" 💧 Light watering
May 4.3" 2.2" 2.1" 💧 Light watering
Jun 4.3" 1.7" 2.6" 🚿 Regular watering
Jul 4.3" 0.6" 3.7" 🚿 Regular watering
Aug 4.3" 0.8" 3.5" 🚿 Regular watering
Sep 4.3" 1.5" 2.8" 🚿 Regular watering
Oct 4.3" 3.5" 0.8" 💧 Light watering
Nov 5.9" 0" ❄️ Dormant
Dec 5.7" 0" ❄️ Dormant

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

Mulberries 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.

Mulberries needs ~20,440 GDD — county provides 2,864 GDD May not mature

Mulberries Planting Timeline — Grays Harbor County, WA

Mulberries Planting Calendar

Activity When Date Range
Transplant Outdoors May 18 May 18 – Jun 1

· 120" apart · Rows 144" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May Transplant Outdoors
June Transplant Outdoors
July
August
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

730–1825 days

🧪 Soil pH

Needs 5.5–7 · Your soil: ideal

🗺️ USDA Zone

Zone 8b

📆 Growing Season

179 days in Grays Harbor County

Growing Tips for Mulberries in Grays Harbor County

Direct sow Mulberries outdoors after April 27 in Grays Harbor County when soil has warmed and frost danger has passed.

Your 179.0-day growing season in Grays Harbor County is tight for Mulberries (730.0-1825.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Plant away from driveways and patios as fallen berries stain. Minimal pruning is needed. Harvest by shaking branches over a tarp. Birds love mulberries so plant extra.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Mulberries in Grays Harbor County, WA?

Grays Harbor County is in Zone 8b with an average last frost of April 27. Plan your Mulberries planting based on this frost date — see the calendar above for exact timing.

What planting zone is Grays Harbor County, WA?

Grays Harbor County, Washington is in USDA Hardiness Zone 8b. The average last spring frost is April 27 and first fall frost is October 23.

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Your Grays Harbor County Garden Planner — Free

A 24-page printable planner built for Grays Harbor County (Zone 8b). 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 Grays Harbor County, WA. Local conditions may vary. Last updated: May 2026.

Sources & credits

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