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When to Plant Ground Cherry in Whitman County, WA

Whitman County, Washington Zone 6b May

What to do in May

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

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. Time to transplant ground cherry

    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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Ground cherries produce small, sweet, tropical-tasting berries enclosed in papery husks. They are related to tomatillos and cape gooseberries and self-sow readily.

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 Ground Cherry during the growing season. With low rainfall, drip irrigation is essential for growing Ground Cherry 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

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) ✗ May not fit
Transplant: May 20 🍅 Harvest: Jul 29 – Sep 23
Recommended (50%) ✗ May not fit
Transplant: May 31 🍅 Harvest: Aug 9 – Oct 4
Safe Start (90%) ✗ May not fit
Transplant: Jun 27 🍅 Harvest: Sep 5 – Oct 31

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 Ground Cherry's growing requirements.

Soil pH

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

Soil Texture

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

Organic Matter

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

How to Plant Ground Cherry

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Succession Planting Ground Cherry

2
successive plantings in your 142-day season

Sow every 7.4 weeks. Last sowing by Jul 11 to harvest before frost.

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 Ground Cherry

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

Month Ground Cherry 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.

Ground Cherry 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.

Ground Cherry needs ~1,160 GDD — county provides 2,272 GDD Excellent fit

Ground Cherry Planting Timeline — Whitman County, WA

Ground Cherry Planting Calendar

Activity When Date Range
Transplant Outdoors May 31 May 31 – Jun 14
Harvest August 9 Aug 9 – Oct 4

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

65–80 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

142 days in Whitman County

Growing Tips for Ground Cherry in Whitman County

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

Common pests for Ground Cherry in this region include tomato hornworm and aphids. Use row covers early in the season and inspect plants weekly.

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

General growing tips

Start seeds indoors 6-8 weeks before last frost. Let fruits fall to the ground naturally when ripe inside their husks. The husk turns brown and papery when the fruit is ready.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Ground Cherry in Whitman County, WA?

Whitman County is in Zone 6b with an average last frost of May 10. Plan your Ground Cherry 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.

🌱

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.