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When to Plant Persimmon in Whitman County, WA

Whitman County, Washington Zone 6b May

May to-do list for Whitman County, Washington

A quick May briefing for Whitman County, Washington gardeners — what's urgent, what's next, and what can wait.

Avg. last frost May 10
Avg. first frost September 29
Soil temp (4") 59°F
Watering Critical
Pest pressure Low
Daylight 14.8 hrs
  1. Transplant persimmon outside

    Pinch off the lowest leaves on each seedling before you plant — it reduces water loss while the roots catch up.

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Persimmons are ornamental trees producing sweet, honey-flavored fruits in fall. American persimmons are astringent until fully ripe while Asian types can be eaten firm.

Whitman County, Washington is in USDA Zone 6b. The average last spring frost is May 10 and the first fall frost is September 29, giving you a growing season of approximately 142 days.

At an elevation of 1,541 feet, Whitman County receives approximately 14.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 88°F, providing good warmth for Persimmon during the growing season. With low rainfall, drip irrigation is essential for growing Persimmon successfully. Mulch heavily to conserve soil moisture.

Whitman County, WA (Zone 6b) Short season
142 days
Last Spring Frost May 10
142 growing days
First Fall Frost September 29
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Whitman 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 20
Recommended (50%) ✓ Fits season
Transplant: May 31
Safe Start (90%) ✓ Fits season
Transplant: Jun 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 Whitman County

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

Soil pH

Your soil pH (5.5–6.7) overlaps with Persimmon's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.0%) — Persimmon will thrive.

How to Plant Persimmon

120"
Between Plants
144"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.4″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 722 gal / 100 sq ft

Monthly Watering Guide for Persimmon

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

Month Persimmon Needs Rainfall You Supplement Action
Jan 2.2" 0" ❄️ Dormant
Feb 1.5" 0" ❄️ Dormant
Mar 1.3" 0" ❄️ Dormant
Apr 1.2" 0" ❄️ Dormant
May 4.3" 0.8" 3.5" 🚿 Regular watering
Jun 4.3" 0.6" 3.7" 🚿 Regular watering
Jul 4.3" 0.3" 4" 🚿 Regular watering
Aug 4.3" 0.2" 4.1" 🚿 Regular watering
Sep 4.3" 0.6" 3.7" 🚿 Regular watering
Oct 1.3" 0" ❄️ Dormant
Nov 2.2" 0" ❄️ Dormant
Dec 2.5" 0" ❄️ Dormant

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

Persimmon 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.

Persimmon needs ~29,200 GDD — county provides 2,272 GDD May not mature

Persimmon Planting Timeline — Whitman County, WA

Persimmon Planting Calendar

Activity When Date Range
Transplant Outdoors May 31 May 31 – Jun 14

· 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 · 1-2 times/week

📅 Days to Maturity

1095–2555 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

142 days in Whitman County

Growing Tips for Persimmon in Whitman County

Direct sow Persimmon outdoors after May 10 in Whitman County when soil has warmed and frost danger has passed.

Your 142.0-day growing season in Whitman County is tight for Persimmon (1095.0-2555.0 days to maturity). Start indoors and choose early-maturing varieties.

Whitman County receives only 14" of rain annually. Persimmon needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Choose self-fertile varieties or plant male and female trees. American types must be fully soft-ripe before eating. Asian varieties may be eaten when firm. Minimal pruning needed.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Persimmon in Whitman County, WA?

Whitman County is in Zone 6b with an average last frost of May 10. Plan your Persimmon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Whitman County, WA?

Whitman County, Washington is in USDA Hardiness Zone 6b. The average last spring frost is May 10 and first fall frost is September 29.

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Your Whitman County Garden Planner — Free

A 24-page printable planner built for Whitman County (Zone 6b). 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 Whitman 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.