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When to Plant Ground Cherry in Knox County, ME

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

Knox County, Maine is in USDA Zone 5b. The average last spring frost is May 2 and the first fall frost is October 12, giving you a growing season of approximately 163 days.

At an elevation of 408 feet, Knox County receives approximately 41.5 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Ground Cherry to ensure they mature before fall.

Knox County, ME (Zone 5b) Moderate season
163 days
Last Spring Frost May 2
163 growing days
First Fall Frost October 12

Knox County Soil Profile

Soil Type

Silt Loam

Soil pH

5.1-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Transplant: May 18 🍅 Harvest: Jul 27 – Sep 21
Recommended (50%) ✓ Fits season (16 days to spare)
Transplant: May 23 🍅 Harvest: Aug 1 – Sep 26
Safe Start (90%) ✓ Fits season (19 days to spare)
Transplant: Jun 5 🍅 Harvest: Aug 14 – Oct 9

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.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Ground Cherry needs ~888 GDD — county provides 1,996 GDD Excellent fit

Ground Cherry Planting Timeline โ€” Knox County, ME

Ground Cherry Planting Calendar

Activity When Date Range
Transplant Outdoors May 23 May 23 โ€“ Jun 6
Harvest August 1 Aug 1 โ€“ Sep 26

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

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

65โ€“80 days

Soil pH

6 โ€“ 7.5

USDA Zone

Zone 5b

Growing Season

163 days

Growing Tips for Knox County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Ground Cherry in Knox County, ME?

Knox County is in Zone 5b with an average last frost of May 2. Plan your Ground Cherry planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Knox County, ME?

Knox County, Maine is in USDA Hardiness Zone 5b. The average last spring frost is May 2 and first fall frost is October 12.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Knox County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

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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 Knox County, ME. Local conditions may vary. Last updated: April 2026.