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When to Plant Garlic in Butte County, CA

Butte County, California Zone 9b May

May to-do list for Butte 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 April 20
Avg. first frost November 10
Soil temp (4") 75°F
Watering Critical
Pest pressure High
Daylight 14.2 hrs

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Garlic is a pungent allium planted in fall and harvested the following summer. Hardneck varieties produce edible flower stalks (scapes) and are more cold-hardy.

Butte County, California is in USDA Zone 9b. The average last spring frost is April 20 and the first fall frost is November 10, giving you a growing season of approximately 204 days.

At an elevation of 144 feet, Butte County receives approximately 44.8 inches of rainfall annually with predominantly loam soil. Summer highs average 90°F, providing good warmth for Garlic during the growing season.

Butte County, CA (Zone 9b) Long season
204 days
Last Spring Frost April 20
204 growing days
First Fall Frost November 10

Butte County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: Mar 26 🍅 Harvest: Jun 25 – Dec 10
Recommended (50%) ✓ Fits season (310 days to spare)
Transplant: Apr 20 🍅 Harvest: Jul 20 – Jan 4
Safe Start (90%) ✓ Fits season (310 days to spare)
Transplant: May 24 🍅 Harvest: Aug 23 – Feb 7

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 Butte County

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

Soil pH

Your soil pH (6.8–7.7) overlaps with Garlic's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Garlic.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Garlic.

How to Plant Garlic

1"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 6 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.9″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Garlic

Garlic needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.

Month Garlic Needs Rainfall You Supplement Action
Jan 9.7" 0" ❄️ Dormant
Feb 9.9" 0" ❄️ Dormant
Mar 6.9" 0" ❄️ Dormant
Apr 2.2" 3" 0" ✅ Rainfall sufficient
May 2.2" 1.1" 1.1" 🚿 Regular watering
Jun 2.2" 0.2" 2" 🚿 Regular watering
Jul 2.2" 0" 2.2" 🚿 Regular watering
Aug 2.2" 0" 2.2" 🚿 Regular watering
Sep 2.2" 0.4" 1.8" 🚿 Regular watering
Oct 2.2" 2.1" 0.1" 💧 Light watering
Nov 2.2" 3.7" 0" ✅ Rainfall sufficient
Dec 7.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Nov in Butte County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Garlic 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.

Garlic needs ~2,888 GDD — county provides 3,570 GDD Good fit

Garlic Planting Timeline — Butte County, CA

Garlic Planting Calendar

Activity When Date Range
Fall Sowing September 29 Sep 29 – Oct 13

Plant 1" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April
May
June
July
August
September Fall Sowing
October Fall Sowing
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Natural rainfall sufficient

📅 Days to Maturity

90–240 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

204 days in Butte County

Growing Tips for Garlic in Butte County

Direct sow Garlic outdoors after April 20 in Butte County when soil has warmed and frost danger has passed.

Your 204.0-day growing season in Butte County is tight for Garlic (90.0-240.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Garlic in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Plant individual cloves pointed end up in fall, 6 weeks before ground freezes. Mulch heavily with straw. Harvest when lower leaves begin to brown but 5-6 green leaves remain.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Garlic in Butte County, CA?

Butte County is in Zone 9b with an average last frost of April 20. Plan your Garlic planting based on this frost date — see the calendar above for exact timing.

What planting zone is Butte County, CA?

Butte County, California is in USDA Hardiness Zone 9b. The average last spring frost is April 20 and first fall frost is November 10.

🌱

Your Butte County Garden Planner — Free

A 24-page printable planner built for Butte 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 Butte 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.