Blog

When to Plant Brussels Sprouts in Amador County, CA

Amador County, California Zone 9b May

Your May planting checklist for Amador County, California

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Amador County, California.

Avg. last frost March 8
Avg. first frost November 25
Soil temp (4") 69°F
Watering Critical
Pest pressure High
Daylight 14.1 hrs
Looking ahead to June
  • First harvests: brussels sprouts

Instant PDF download. No spam, unsubscribe any time.

Brussels sprouts are a cold-hardy brassica that produces miniature cabbage-like heads along a tall stalk. Flavor improves after a light frost.

Amador County, California is in USDA Zone 9b. The average last spring frost is March 8 and the first fall frost is November 25, giving you a growing season of approximately 262 days.

At an elevation of 1,335 feet, Amador County receives approximately 42.7 inches of rainfall annually with predominantly loam soil. Summer highs average 89°F, providing good warmth for Brussels Sprouts during the growing season.

Amador County, CA (Zone 9b) Long season
262 days
Last Spring Frost March 8
262 growing days
First Fall Frost November 25
Share this guide:

Amador County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (130 days to spare)
Start indoors: Jan 8 Transplant: Feb 5 🍅 Harvest: May 7 – Jul 2
Recommended (50%) ✓ Fits season (115 days to spare)
Start indoors: Feb 8 Transplant: Mar 8 🍅 Harvest: Jun 7 – Aug 2
Safe Start (90%) ✓ Fits season (97 days to spare)
Start indoors: Mar 22 Transplant: Apr 19 🍅 Harvest: Jul 19 – Sep 13

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 Amador County

How your county's soil matches Brussels Sprouts's growing requirements.

Soil pH

Your soil pH (6.7–7.8) overlaps with Brussels Sprouts's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in Amador County is excellent for Brussels Sprouts — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.7%). Annual compost additions will help Brussels Sprouts.

How to Plant Brussels Sprouts

1"
Planting Depth
15"
Between Plants
24"
Between Rows

Fall planting: Sow 8 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
0.7″/week
You supply
0.3″/week
Watering frequency Only during dry spells
Season total 603 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Brussels Sprouts

Brussels Sprouts needs approximately 0.9 inches of water per week (3.9" per month). Here's how your county's rainfall compares month by month.

Month Brussels Sprouts Needs Rainfall You Supplement Action
Jan 9.4" 0" ❄️ Dormant
Feb 8" 0" ❄️ Dormant
Mar 3.9" 6" 0" ✅ Rainfall sufficient
Apr 3.9" 3.5" 0.4" 💧 Light watering
May 3.9" 1" 2.9" 🚿 Regular watering
Jun 3.9" 0.2" 3.7" 🚿 Regular watering
Jul 3.9" 0" 3.9" 🚿 Regular watering
Aug 3.9" 0" 3.9" 🚿 Regular watering
Sep 3.9" 0.5" 3.4" 🚿 Regular watering
Oct 3.9" 1.9" 2" 🚿 Regular watering
Nov 3.9" 4.3" 0" ✅ Rainfall sufficient
Dec 7.8" 0" ❄️ Dormant

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

Brussels Sprouts 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.

Brussels Sprouts needs ~1,842 GDD — county provides 4,388 GDD Excellent fit

Brussels Sprouts Planting Timeline — Amador County, CA

Brussels Sprouts Planting Calendar

Activity When Date Range
Start Indoors February 8 Feb 8 – Feb 22
Transplant Outdoors March 8 Mar 8 – Mar 22
Direct Sow February 15 Feb 15 – Mar 8
Harvest June 7 Jun 7 – Aug 2
Fall Sowing September 30 Sep 30 – Oct 14

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

Month-by-Month Timeline

MonthActivities
January
February Start Indoors Direct Sow
March Transplant Outdoors Direct Sow
April
May
June Harvest
July Harvest
August Harvest
September Fall Sowing
October Fall Sowing
November
December
Share this guide:

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · Only during dry spells

📅 Days to Maturity

90–130 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

262 days in Amador County

Growing Tips for Brussels Sprouts in Amador County

Direct sow Brussels Sprouts outdoors after March 08 in Amador County when soil has warmed and frost danger has passed.

Common pests for Brussels Sprouts in this region include cabbage worm and flea beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 12-14 weeks before first fall frost. Stake tall plants to prevent toppling. Remove lower leaves as sprouts develop to improve air circulation.

Companion Planting

Good Companions

Avoid Planting Near

  • Tomatoes
  • Strawberries

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Brussels Sprouts in Amador County, CA?

Amador County is in Zone 9b with an average last frost of March 8. Plan your Brussels Sprouts planting based on this frost date — see the calendar above for exact timing.

What planting zone is Amador County, CA?

Amador County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 8 and first fall frost is November 25.

🌱

Your Amador County Garden Planner — Free

A 24-page printable planner built for Amador 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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Amador 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.