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When to Plant Collard Greens in Tehama County, CA

Tehama County, California Zone 9b May

Your May game plan for Tehama County, California

May is a pivotal month for Tehama County, California gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost March 6
Avg. first frost November 28
Soil temp (4") 72°F
Watering High
Pest pressure High
Daylight 14.2 hrs
  1. It's harvest week for collard greens

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

To set up a strong June, finish these tasks
  • First harvests: collard greens

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Collard greens are a heat-tolerant member of the cabbage family with large, sturdy leaves. They are a Southern staple and one of the most nutritious leafy greens.

Tehama 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 78 feet, Tehama County receives approximately 44 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Collard Greens to ensure they mature before fall.

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

Tehama County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (151 days to spare)
Start indoors: Jan 26 Transplant: Feb 23 🍅 Harvest: Apr 20 – Jun 22
Recommended (50%) ✓ Fits season (148 days to spare)
Start indoors: Feb 6 Transplant: Mar 6 🍅 Harvest: May 1 – Jul 3
Safe Start (90%) ✓ Fits season (126 days to spare)
Start indoors: Mar 21 Transplant: Apr 18 🍅 Harvest: Jun 13 – Aug 15

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 Tehama County

How your county's soil matches Collard Greens's growing requirements.

Soil pH

Your soil pH (6.8–7.6) is more alkaline than Collard Greens prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Tehama County is excellent for Collard Greens — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Collard Greens.

How to Plant Collard Greens

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

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

Succession Planting Collard Greens

5
successive plantings in your 267-day season

Sow every 6.3 weeks. Last sowing by Sep 14 to harvest before frost.

For a dedicated fall crop, sow by Oct 03.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.7″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 308 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Collard Greens

Collard Greens needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Collard Greens Needs Rainfall You Supplement Action
Jan 10.2" 0" ❄️ Dormant
Feb 8.5" 0" ❄️ Dormant
Mar 3.5" 7" 0" ✅ Rainfall sufficient
Apr 3.5" 3.5" 0" ✅ Rainfall sufficient
May 3.5" 1.3" 2.2" 🚿 Regular watering
Jun 3.5" 0.2" 3.3" 🚿 Regular watering
Jul 3.5" 0" 3.5" 🚿 Regular watering
Aug 3.5" 0" 3.5" 🚿 Regular watering
Sep 3.5" 0.4" 3.1" 🚿 Regular watering
Oct 3.5" 1.8" 1.7" 💧 Light watering
Nov 3.5" 4.2" 0" ✅ Rainfall sufficient
Dec 6.9" 0" ❄️ Dormant

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

Collard Greens 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.

Collard Greens needs ~748 GDD — county provides 3,070 GDD Excellent fit

Collard Greens Planting Timeline — Tehama County, CA

Collard Greens Planting Calendar

Activity When Date Range
Start Indoors February 6 Feb 6 – Feb 20
Transplant Outdoors March 6 Mar 6 – Mar 20
Direct Sow February 13 Feb 13 – Mar 6
Harvest May 1 May 1 – Jul 3
Fall Sowing October 3 Oct 3 – Oct 17

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 Harvest
June Harvest
July Harvest
August
September
October Fall Sowing
November
December

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Only during dry spells

📅 Days to Maturity

55–75 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

267 days in Tehama County

Growing Tips for Collard Greens in Tehama County

Direct sow Collard Greens outdoors after March 06 in Tehama County when soil has warmed and frost danger has passed.

Common pests for Collard Greens 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 or direct sow 4-6 weeks before last frost. Harvest lower leaves first, leaving the growing tip intact. Flavor improves after exposure to frost.

Companion Planting

Good Companions

Avoid Planting Near

  • Strawberries
  • Tomatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Collard Greens in Tehama County, CA?

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

What planting zone is Tehama County, CA?

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

🌱

Your Tehama County Garden Planner — Free

A 24-page printable planner built for Tehama 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 Tehama 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.