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When to plant Comfrey in Yolo County County,

Yolo County County's 298-day season only supports one Comfrey planting per year. Sow between February 16 and March 2 for the best chance at full maturity before December 3.

When to Plant Comfrey in Yolo County, CA

Yolo County, California Zone 9b June

June in Yolo County, California — your action list

Your garden in Yolo County, California is working on a schedule, even when you're not. Here's where you should be this June.

Avg. last frost February 9
Avg. first frost December 3
Soil temp (4") 85°F
Watering Critical
Pest pressure High
Daylight 14.7 hrs
  1. Basket week: comfrey

    This is the payoff month. Bring a basket, bring a friend, and get into the beds.

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Comfrey is a vigorous perennial herb valued as a dynamic accumulator of nutrients. Its leaves make excellent mulch, compost activator, and liquid fertilizer.

Yolo County, California is in USDA Zone 9b. The average last spring frost is February 9 and the first fall frost is December 3, giving you a growing season of approximately 297 days.

At an elevation of 163 feet, Yolo County receives approximately 27.7 inches of rainfall annually with predominantly loam soil. Summer highs average 95°F, so Comfrey may need afternoon shade and extra watering during peak heat.

Yolo County, CA (Zone 9b) Year-round
297 days
Last Spring Frost February 9
297 growing days
First Fall Frost December 3

Yolo County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.8

Drainage

Well Drained

Comfrey Planting Risk Windows

Early Start (70% safe) ✓ Fits season (165 days to spare)
Transplant: Feb 1 🍅 Harvest: Apr 5 – Jun 14
Recommended (50%) ✓ Fits season (157 days to spare)
Transplant: Feb 16 🍅 Harvest: Apr 20 – Jun 29
Safe Start (90%) ✓ Fits season (141 days to spare)
Transplant: Mar 20 🍅 Harvest: May 22 – Jul 31

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 Yolo County

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

Soil pH

Your soil pH (6.7–7.8) is more alkaline than Comfrey prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Comfrey.

How to Plant Comfrey

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

Succession Planting Comfrey

5
successive plantings in your 297-day season

Sow every 6.9 weeks. Last sowing by Sep 04 to harvest before frost.

Comfrey Water Budget

Plant needs
1.0″/week
Rainfall provides
0.4″/week
You supply
0.7″/week
Watering frequency 2-3 times/week
Season total 1,940 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Comfrey

Comfrey needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Comfrey Needs Rainfall You Supplement Action
Jan 6" 0" ❄️ Dormant
Feb 4.3" 5.4" 0" ✅ Rainfall sufficient
Mar 4.3" 4" 0.3" 💧 Light watering
Apr 4.3" 2.3" 2" 💧 Light watering
May 4.3" 0.8" 3.5" 🚿 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" 1.1" 3.2" 🚿 Regular watering
Nov 4.3" 2.6" 1.7" 💧 Light watering
Dec 4.3" 5.1" 0" ✅ Rainfall sufficient

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

Comfrey 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.

Comfrey needs ~1,594 GDD — county provides 6,332 GDD Excellent fit

Comfrey Planting Timeline — Yolo County, CA

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors February 16 Feb 16 – Mar 2
Harvest April 20 Apr 20 – Jun 29

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Partial Shade (3-6 hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

60–90 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

297 days in Yolo County

Growing Tips for Comfrey in Yolo County

Direct sow Comfrey outdoors after February 09 in Yolo County when soil has warmed and frost danger has passed.

General growing tips

Plant root cuttings 2 inches deep. Choose Bocking 14 variety to prevent self-seeding. Cut leaves 3-4 times per season for mulch or compost. Avoid planting near pathways as it spreads.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Comfrey in Yolo County, CA?

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

What planting zone is Yolo County, CA?

Yolo County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 9 and first fall frost is December 3.

When should I plant Comfrey in Yolo County, ?

In Yolo County, , plant Comfrey after the last frost (around February 9) and before the first frost (around December 3). Best results when soil holds above 50°F.

What growing zone is Yolo County, for Comfrey?

Yolo County sits in USDA Zone 9b. Comfrey grows reliably in zones 3a through 9b, so it's a good fit here.

Can Comfrey grow in Yolo County's climate?

Yes — Comfrey grows well in Yolo County's temperate climate. Yolo County averages a 298-day frost-free season, with last frost around February 9 and first frost around December 3.

🌱

Your Yolo County Garden Planner — Free

A 22-page printable planner built for Yolo 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 Yolo County, CA. Local conditions may vary. Last updated: June 2026.

Sources & credits

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