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When to Plant Mulberries in Fremont County, ID

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

Fremont County, Idaho is in USDA Zone 4b. The average last spring frost is June 12 and the first fall frost is September 6, giving you a growing season of approximately 86 days.

At an elevation of 5,282 feet, Fremont County receives approximately 12.7 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Mulberries to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Mulberries successfully. Mulch heavily to conserve soil moisture.

Fremont County, ID (Zone 4b) Very short season
86 days
Last Spring Frost June 12
86 growing days
First Fall Frost September 6

Fremont County Soil Profile

Soil Type

Loam

Soil pH

6.4-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: Jun 20
Recommended (50%) ✓ Fits season
Transplant: Jul 10
Safe Start (90%) ✓ Fits season
Transplant: Jul 25

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
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 349 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Mulberries needs ~16,608 GDD — county provides 1,118 GDD May not mature

Mulberries Planting Timeline โ€” Fremont County, ID

Mulberries Planting Calendar

Activity When Date Range
Transplant Outdoors July 10 Jul 10 โ€“ Jul 24

ยท 120" apart ยท Rows 144" apart

Month-by-Month Timeline

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

Growing Conditions

Sun

Full Sun (6-8+ hours)

Water

Moderate โ€” regular watering

Days to Maturity

730โ€“1825 days

Soil pH

5.5 โ€“ 7

USDA Zone

Zone 4b

Growing Season

86 days

Growing Tips for Fremont County

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

Level Up Your Garden

Frequently Asked Questions

When should I plant Mulberries in Fremont County, ID?

Fremont County is in Zone 4b with an average last frost of June 12. Plan your Mulberries planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Fremont County, ID?

Fremont County, Idaho is in USDA Hardiness Zone 4b. The average last spring frost is June 12 and first fall frost is September 6.

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Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Fremont County gardeners in Zone 4b 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 Fremont County, ID. Local conditions may vary. Last updated: April 2026.