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When to Plant Feverfew in Colusa County, CA

Colusa County, California Zone 9b May

Your May game plan for Colusa County, California

May is a pivotal month for Colusa 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") 74°F
Watering Critical
Pest pressure High
Daylight 14.1 hrs
A few tasks this May that'll pay off in June
  • First harvests: feverfew

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Feverfew is a bushy perennial herb with small daisy-like flowers and aromatic leaves. It has been used traditionally for headache relief and is a cheerful garden plant.

Colusa 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 112 feet, Colusa County receives approximately 29.8 inches of rainfall annually with predominantly loam soil. Summer highs average 94°F, providing good warmth for Feverfew during the growing season.

Colusa 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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Colusa County Soil Profile

Soil Type

Loam

Soil pH

6.6-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (95 days to spare)
Transplant: Mar 2 🍅 Harvest: Jun 1 – Aug 17
Recommended (50%) ✓ Fits season (92 days to spare)
Transplant: Mar 13 🍅 Harvest: Jun 12 – Aug 28
Safe Start (90%) ✓ Fits season (70 days to spare)
Transplant: Apr 25 🍅 Harvest: Jul 25 – Oct 10

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 Colusa County

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

Soil pH

Your soil pH (6.6–7.5) is more alkaline than Feverfew prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Drainage

Drainage is adequate for Feverfew.

Organic Matter

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

How to Plant Feverfew

0.5"
Planting Depth
8"
Between Plants
12"
Between Rows

Plant Water Budget

Plant needs
0.5″/week
Rainfall provides
0.5″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 517 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Feverfew

Feverfew 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 Feverfew Needs Rainfall You Supplement Action
Jan 6.2" 0" ❄️ Dormant
Feb 6.7" 0" ❄️ Dormant
Mar 2.2" 4.7" 0" ✅ Rainfall sufficient
Apr 2.2" 2" 0.2" 💧 Light watering
May 2.2" 0.7" 1.5" 🚿 Regular watering
Jun 2.2" 0.1" 2.1" 🚿 Regular watering
Jul 2.2" 0" 2.2" 🚿 Regular watering
Aug 2.2" 0" 2.2" 🚿 Regular watering
Sep 2.2" 0.3" 1.9" 🚿 Regular watering
Oct 2.2" 1.1" 1.1" 🚿 Regular watering
Nov 2.2" 3" 0" ✅ Rainfall sufficient
Dec 4.9" 0" ❄️ Dormant

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

Feverfew 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.

Feverfew needs ~2,152 GDD — county provides 5,473 GDD Excellent fit

Feverfew Planting Timeline — Colusa County, CA

Feverfew Planting Calendar

Activity When Date Range
Transplant Outdoors March 13 Mar 13 – Mar 27
Harvest June 12 Jun 12 – Aug 28

Plant 0.5" deep · 8" apart · Rows 12" apart

Month-by-Month Timeline

MonthActivities
January
February
March Transplant Outdoors
April
May
June Harvest
July Harvest
August Harvest
September
October
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.5"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

267 days in Colusa County

Growing Tips for Feverfew in Colusa County

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

Common pests for Feverfew in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors or direct sow on the soil surface. Deadhead regularly to prevent aggressive self-seeding. Divide clumps every 2-3 years to maintain vigor.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Feverfew in Colusa County, CA?

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

What planting zone is Colusa County, CA?

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

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Your Colusa County Garden Planner — Free

A 24-page printable planner built for Colusa 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 Colusa 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.