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When to Plant Mulberries in Glenn County, CA

Glenn County, California Zone 9b May

Your May game plan for Glenn County, California

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost March 6
Avg. first frost November 28
Soil temp (4") 75°F
Watering Critical
Pest pressure High
Daylight 14.2 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.

Glenn County, California is in USDA Zone 9b. The average last spring frost is March 6 and the first fall frost is November 28, giving you a growing season of approximately 267 days.

At an elevation of 270 feet, Glenn County receives approximately 27.1 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Mulberries during the growing season.

Glenn County, CA (Zone 9b) Long season
267 days
Last Spring Frost March 6
267 growing days
First Fall Frost November 28
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Glenn County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season
Transplant: Mar 9
Recommended (50%) ✓ Fits season
Transplant: Mar 20
Safe Start (90%) ✓ Fits season
Transplant: May 2

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 Glenn County

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

Soil pH

Your soil pH (6.5–7.9) is more alkaline than Mulberries prefers (5.5–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (3.0%). 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
0.4″/week
You supply
0.7″/week
Watering frequency 1-2 times/week
Season total 1,636 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 5.6" 0" ❄️ Dormant
Feb 5.3" 0" ❄️ Dormant
Mar 4.3" 4.4" 0" ✅ Rainfall sufficient
Apr 4.3" 2.5" 1.8" 💧 Light watering
May 4.3" 0.7" 3.6" 🚿 Regular watering
Jun 4.3" 0.1" 4.2" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.3" 4" 🚿 Regular watering
Oct 4.3" 1.3" 3" 🚿 Regular watering
Nov 4.3" 2.5" 1.8" 💧 Light watering
Dec 4.3" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Glenn 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 ~20,440 GDD — county provides 4,272 GDD May not mature

Mulberries Planting Timeline — Glenn County, CA

Mulberries Planting Calendar

Activity When Date Range
Transplant Outdoors March 20 Mar 20 – Apr 3

· 120" apart · Rows 144" apart

Month-by-Month Timeline

MonthActivities
January
February
March Transplant Outdoors
April Transplant Outdoors
May
June
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 9b

📆 Growing Season

267 days in Glenn County

Growing Tips for Mulberries in Glenn County

Direct sow Mulberries outdoors after March 06 in Glenn County when soil has warmed and frost danger has passed.

Your 267.0-day growing season in Glenn County is tight for Mulberries (730.0-1825.0 days to maturity). Start indoors and choose early-maturing varieties.

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 Glenn County, CA?

Glenn County is in Zone 9b with an average last frost of March 6. Plan your Mulberries planting based on this frost date — see the calendar above for exact timing.

What planting zone is Glenn County, CA?

Glenn County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 6 and first fall frost is November 28.

🌱

Your Glenn County Garden Planner — Free

A 24-page printable planner built for Glenn County (Zone 9b). 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 Glenn County, CA. 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.