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When to Plant Edamame in Marin County, CA

Marin County, California Zone 9b May

This month in Marin County, California

We've pulled the most time-sensitive tasks for Marin County, California this May and put them front and centre. Tackle them in order.

Avg. last frost February 26
Avg. first frost November 26
Soil temp (4") 79°F
Watering Critical
Pest pressure High
Daylight 14.1 hrs
  1. Basket week: edamame

    Check every 1–2 days. Many of these get tough or go to seed if you wait too long.

Coming up in June — start thinking about
  • First harvests: edamame

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Edamame are soybeans harvested at the immature green stage for a sweet, nutty snack. They are high in protein and easy to grow in warm climates.

Marin County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 26, giving you a growing season of approximately 273 days.

At an elevation of 302 feet, Marin County receives approximately 36 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 81°F, so choose short-season varieties of Edamame to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Edamame will need more frequent watering and organic matter to retain nutrients.

Marin County, CA (Zone 9b) Year-round
273 days
Last Spring Frost February 26
273 growing days
First Fall Frost November 26
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Marin County Soil Profile

Soil Type

Sandy Loam

Soil pH

6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (166 days to spare)
Transplant: Feb 10 🍅 Harvest: Apr 28 – Jun 9
Recommended (50%) ✓ Fits season (154 days to spare)
Transplant: Feb 26 🍅 Harvest: May 14 – Jun 25
Safe Start (90%) ✓ Fits season (140 days to spare)
Transplant: Apr 2 🍅 Harvest: Jun 18 – Jul 30

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 Marin County

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

Soil pH

Your soil pH (6.0–6.9) is within Edamame's preferred range (6.0–7.0).

Soil Texture

Sandy soil in Marin County warms quickly in spring but drains fast. Edamame will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Edamame.

How to Plant Edamame

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

Succession Planting Edamame

4
successive plantings in your 273-day season

Sow every 8.6 weeks. Last sowing by Aug 18 to harvest before frost.

Plant Water Budget

Plant needs
0.9″/week
Rainfall provides
0.6″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 1,019 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Edamame

Edamame 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 Edamame Needs Rainfall You Supplement Action
Jan 7.2" 0" ❄️ Dormant
Feb 3.9" 6.5" 0" ✅ Rainfall sufficient
Mar 3.9" 6.2" 0" ✅ Rainfall sufficient
Apr 3.9" 2.7" 1.2" 💧 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" 0.4" 3.5" 🚿 Regular watering
Oct 3.9" 1.4" 2.5" 🚿 Regular watering
Nov 3.9" 3.5" 0.4" 💧 Light watering
Dec 6.9" 0" ❄️ Dormant

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

Edamame 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.

Edamame needs ~941 GDD — county provides 2,945 GDD Excellent fit

Edamame Planting Timeline — Marin County, CA

Edamame Planting Calendar

Activity When Date Range
Direct Sow March 5 Mar 5 – Mar 26
Harvest May 21 May 21 – Jul 2

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.9"/week · 1-2 times/week

📅 Days to Maturity

75–100 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 9b

📆 Growing Season

273 days in Marin County

Growing Tips for Edamame in Marin County

Direct sow Edamame outdoors after February 26 in Marin County when soil has warmed and frost danger has passed.

Sandy soil in Marin County dries quickly — mulch Edamame with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Common pests for Edamame in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow after soil is warm. Do not over-fertilize with nitrogen. Harvest when pods are plump and bright green but before they start to yellow. Steam or boil pods before eating.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Edamame in Marin County, CA?

Marin County is in Zone 9b with an average last frost of February 26. Plan your Edamame planting based on this frost date — see the calendar above for exact timing.

What planting zone is Marin County, CA?

Marin County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 26.

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Your Marin County Garden Planner — Free

A 24-page printable planner built for Marin 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 Marin 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.