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When to Plant Mulberries in Franklin County, ID

Franklin County, Idaho Zone 5a April

This month in Franklin County, Idaho

Here's what deserves your attention in Franklin County, Idaho this month. Everything below is tailored to Zone 5a and timed around your local frost dates.

Avg. last frost May 19
Avg. first frost October 3
Soil temp (4") 23°F
Watering High
Pest pressure Low
Daylight 13.2 hrs

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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.

Franklin County, Idaho is in USDA Zone 5a. The average last spring frost is May 19 and the first fall frost is October 3, giving you a growing season of approximately 137 days.

At an elevation of 7,665 feet, Franklin County receives approximately 18.5 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Mulberries during the growing season. With low rainfall, drip irrigation is essential for growing Mulberries successfully. Mulch heavily to conserve soil moisture.

Franklin County, ID (Zone 5a) Short season
137 days
Last Spring Frost May 19
137 growing days
First Fall Frost October 3
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Franklin County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: May 27
Recommended (50%) ✓ Fits season
Transplant: Jun 9
Safe Start (90%) ✓ Fits season
Transplant: Jul 4

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 Franklin County

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

Soil pH

Your soil pH (6.7–7.7) is more alkaline than Mulberries prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.6%). Annual compost additions will help Mulberries.

How to Plant Mulberries

120"
Between Plants
144"
Between Rows

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 633 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

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 1.4" 0" ❄️ Dormant
Feb 1.1" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 2" 0" ❄️ Dormant
May 4.3" 1.9" 2.4" 🚿 Regular watering
Jun 4.3" 1.3" 3" 🚿 Regular watering
Jul 4.3" 1.8" 2.5" 🚿 Regular watering
Aug 4.3" 2" 2.3" 🚿 Regular watering
Sep 4.3" 1.6" 2.7" 🚿 Regular watering
Oct 4.3" 1.8" 2.5" 🚿 Regular watering
Nov 1.2" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Franklin 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 ~19,482 GDD — county provides 2,089 GDD May not mature

Mulberries Planting Timeline — Franklin County, ID

Mulberries Planting Calendar

Activity When Date Range
Transplant Outdoors June 9 Jun 9 – Jun 23

· 120" apart · Rows 144" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
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

730–1825 days

🧪 Soil pH

Needs 5.5–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

137 days in Franklin County

Growing Tips for Mulberries in Franklin County

Direct sow Mulberries outdoors after May 19 in Franklin County when soil has warmed and frost danger has passed.

Your 137.0-day growing season in Franklin County is tight for Mulberries (730.0-1825.0 days to maturity). Start indoors and choose early-maturing varieties.

Franklin County receives only 18" of rain annually. Mulberries needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Franklin County, ID?

Franklin County is in Zone 5a with an average last frost of May 19. Plan your Mulberries planting based on this frost date — see the calendar above for exact timing.

What planting zone is Franklin County, ID?

Franklin County, Idaho is in USDA Hardiness Zone 5a. The average last spring frost is May 19 and first fall frost is October 3.

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Your Franklin County Garden Planner — Free

A 24-page printable planner built for Franklin County (Zone 5a). 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 Franklin County, ID. Local conditions may vary. Last updated: April 2026.

Sources & credits

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