Blog

When to Plant Comfrey in Monterey County, CA

Monterey County, California Zone 9b May

May in Monterey County, California — your action list

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

Avg. last frost March 13
Avg. first frost November 17
Soil temp (4") 76°F
Watering Critical
Pest pressure High
Daylight 13.9 hrs
  1. Collect comfrey at their peak

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

Get ahead of June
  • First harvests: comfrey

Instant PDF download. No spam, unsubscribe any time.

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

Monterey County, California is in USDA Zone 9b. The average last spring frost is March 13 and the first fall frost is November 17, giving you a growing season of approximately 249 days.

At an elevation of 260 feet, Monterey County receives approximately 12.5 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Comfrey during the growing season. With low rainfall, drip irrigation is essential for growing Comfrey successfully. Mulch heavily to conserve soil moisture.

Monterey County, CA (Zone 9b) Long season
249 days
Last Spring Frost March 13
249 growing days
First Fall Frost November 17

Monterey County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (108 days to spare)
Transplant: Mar 6 🍅 Harvest: May 8 – Jul 17
Recommended (50%) ✓ Fits season (109 days to spare)
Transplant: Mar 20 🍅 Harvest: May 22 – Jul 31
Safe Start (90%) ✓ Fits season (74 days to spare)
Transplant: May 24 🍅 Harvest: Jul 26 – Oct 4

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 Monterey County

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

Soil pH

Your soil pH (6.7–7.2) overlaps with Comfrey's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

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

How to Plant Comfrey

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

Succession Planting Comfrey

4
successive plantings in your 249-day season

Sow every 6.9 weeks. Last sowing by Aug 19 to harvest before frost.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.2″/week
You supply
1.0″/week
Watering frequency 2-3 times/week
Season total 2,099 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 2.7" 0" ❄️ Dormant
Feb 2.6" 0" ❄️ Dormant
Mar 4.3" 2.1" 2.2" 🚿 Regular watering
Apr 4.3" 1" 3.3" 🚿 Regular watering
May 4.3" 0.3" 4" 🚿 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" 0.1" 4.2" 🚿 Regular watering
Oct 4.3" 0.5" 3.8" 🚿 Regular watering
Nov 4.3" 1.2" 3.1" 🚿 Regular watering
Dec 1.9" 0" ❄️ Dormant

Water needs are for active growing months only (Mar–Nov in Monterey 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 ~1,481 GDD — county provides 4,917 GDD Excellent fit

Comfrey Planting Timeline — Monterey County, CA

Comfrey Planting Calendar

Activity When Date Range
Transplant Outdoors March 20 Mar 20 – Apr 3
Harvest May 22 May 22 – Jul 31

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

Month-by-Month Timeline

MonthActivities
January
February
March Transplant Outdoors
April Transplant Outdoors
May Harvest
June Harvest
July Harvest
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: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

249 days in Monterey County

Growing Tips for Comfrey in Monterey County

Direct sow Comfrey outdoors after March 13 in Monterey County when soil has warmed and frost danger has passed.

Monterey County receives only 12" of rain annually. Comfrey needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Monterey County, CA?

Monterey County is in Zone 9b with an average last frost of March 13. Plan your Comfrey planting based on this frost date — see the calendar above for exact timing.

What planting zone is Monterey County, CA?

Monterey County, California is in USDA Hardiness Zone 9b. The average last spring frost is March 13 and first fall frost is November 17.

🌱

Your Monterey County Garden Planner — Free

A 24-page printable planner built for Monterey 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 Monterey 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.