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When to Plant Soybeans in Mono County, CA

Soybeans (edamame) are a high-protein legume that fixes nitrogen in the soil. Fresh green soybeans harvested at the edamame stage are a nutritious snack.

Mono County, California is in USDA Zone 5b. The average last spring frost is June 18 and the first fall frost is August 20, giving you a growing season of approximately 63 days.

At an elevation of 2,381 feet, Mono County receives approximately 13.3 inches of rainfall annually with predominantly loam soil. Summer highs average 84ยฐF, so choose short-season varieties of Soybeans to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Soybeans successfully. Mulch heavily to conserve soil moisture.

Mono County, CA (Zone 5b) Very short season
63 days
Last Spring Frost June 18
63 growing days
First Fall Frost August 20

Mono County Soil Profile

Soil Type

Loam

Soil pH

6-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Transplant: May 22 🍅 Harvest: Aug 14 – Oct 9
Recommended (50%) ✗ May not fit
Transplant: Jun 18 🍅 Harvest: Sep 10 – Nov 5
Safe Start (90%) ✗ May not fit
Transplant: Jun 30 🍅 Harvest: Sep 22 – Nov 17

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 Mono County

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

Soil pH

Your soil pH (6.0โ€“7.5) overlaps with Soybeans's range (6.0โ€“7.0), though not a perfect match.

Soil Texture

The loam soil in Mono County is excellent for Soybeans โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Soybeans

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 76 gal / 100 sq ft
Drought risk

Water stress score is 10/10 โ€” consider drought-tolerant varieties and mulching

Monthly Watering Guide for Soybeans

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

Month Soybeans Needs Rainfall You Supplement Action
Jan โ€” 2.7" 0" โ„๏ธ Dormant
Feb โ€” 3.1" 0" โ„๏ธ Dormant
Mar โ€” 1.9" 0" โ„๏ธ Dormant
Apr โ€” 1" 0" โ„๏ธ Dormant
May โ€” 0.3" 0" โ„๏ธ Dormant
Jun 4.3" 0.1" 4.2" ๐Ÿšฟ Regular watering
Jul 4.3" 0" 4.3" ๐Ÿšฟ Regular watering
Aug 4.3" 0" 4.3" ๐Ÿšฟ Regular watering
Sep โ€” 0.2" 0" โ„๏ธ Dormant
Oct โ€” 0.6" 0" โ„๏ธ Dormant
Nov โ€” 1.1" 0" โ„๏ธ Dormant
Dec โ€” 2.4" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Junโ€“Aug in Mono County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Soybeans 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" โ€” every day above 50ยฐF 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.

Soybeans needs ~1,300 GDD — county provides 819 GDD May not mature

Soybeans Planting Timeline โ€” Mono County, CA

Soybeans Planting Calendar

Activity When Date Range
Direct Sow June 25 Jun 25 โ€“ Jul 16
Harvest September 17 Sep 17 โ€“ Nov 12

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

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April โ€”
May โ€”
June Direct Sow
July Direct Sow
August โ€”
September Harvest
October Harvest
November Harvest
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท Only during dry spells

๐Ÿ“… Days to Maturity

80โ€“120 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 5b

๐Ÿ“† Growing Season

63 days in Mono County

Growing Tips for Soybeans in Mono County

Direct sow Soybeans outdoors after June 18 in Mono County when soil has warmed and frost danger has passed.

Your 63.0-day growing season in Mono County is tight for Soybeans (80.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

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

Mono County receives only 13" of rain annually. Soybeans needs consistent moisture โ€” install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow after soil warms to 60F. Plant in blocks rather than rows for better pollination. Harvest for edamame when pods are plump and bright green.

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 Soybeans in Mono County, CA?

Mono County is in Zone 5b with an average last frost of June 18. Plan your Soybeans planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Mono County, CA?

Mono County, California is in USDA Hardiness Zone 5b. The average last spring frost is June 18 and first fall frost is August 20.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Mono County gardeners in Zone 5b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

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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 Mono County, CA. Local conditions may vary. Last updated: April 2026.