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When to Plant Kidney Beans in San Joaquin County, CA

San Joaquin County, California Zone 9b May

Your May gardening checklist

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

Avg. last frost February 4
Avg. first frost December 6
Soil temp (4") 77°F
Watering Critical
Pest pressure High
Daylight 14 hrs
  1. It's harvest week for kidney beans

    Taste as you pick. The first ripe produce is the best feedback loop you'll get all season.

A few tasks this May that'll pay off in June
  • First harvests: kidney beans

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Kidney beans are a popular dry bean variety named for their shape, available in red and white types. They are the classic bean for chili and red beans and rice.

San Joaquin County, California is in USDA Zone 9b. The average last spring frost is February 4 and the first fall frost is December 6, giving you a growing season of approximately 305 days.

At an elevation of 220 feet, San Joaquin County receives approximately 15 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Kidney Beans during the growing season. With low rainfall, drip irrigation is essential for growing Kidney Beans successfully. Mulch heavily to conserve soil moisture.

San Joaquin County, CA (Zone 9b) Year-round
305 days
Last Spring Frost February 4
305 growing days
First Fall Frost December 6
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San Joaquin County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (189 days to spare)
Transplant: Jan 18 🍅 Harvest: Apr 19 – May 24
Recommended (50%) ✓ Fits season (179 days to spare)
Transplant: Feb 4 🍅 Harvest: May 6 – Jun 10
Safe Start (90%) ✓ Fits season (163 days to spare)
Transplant: Mar 5 🍅 Harvest: Jun 4 – Jul 9

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 San Joaquin County

How your county's soil matches Kidney Beans's growing requirements.

Soil pH

Your soil pH (6.4–7.8) overlaps with Kidney Beans's range (6.0–7.5), though not a perfect match.

Soil Texture

The loam soil in San Joaquin County is excellent for Kidney Beans — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Kidney Beans

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

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 2,595 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Kidney Beans

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

Month Kidney Beans Needs Rainfall You Supplement Action
Jan 2.9" 0" ❄️ Dormant
Feb 4.3" 3.1" 1.2" 💧 Light watering
Mar 4.3" 2.6" 1.7" 💧 Light watering
Apr 4.3" 1.2" 3.1" 🚿 Regular watering
May 4.3" 0.4" 3.9" 🚿 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" 0.2" 4.1" 🚿 Regular watering
Oct 4.3" 0.7" 3.6" 🚿 Regular watering
Nov 4.3" 1.3" 3" 🚿 Regular watering
Dec 4.3" 2.6" 1.7" 💧 Light watering

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

Kidney Beans 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.

Kidney Beans needs ~1,926 GDD — county provides 6,043 GDD Excellent fit

Kidney Beans Planting Timeline — San Joaquin County, CA

Kidney Beans Planting Calendar

Activity When Date Range
Direct Sow February 11 Feb 11 – Mar 4
Harvest May 13 May 13 – Jun 17

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

85–110 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 9b

📆 Growing Season

305 days in San Joaquin County

Growing Tips for Kidney Beans in San Joaquin County

Direct sow Kidney Beans outdoors after February 04 in San Joaquin County when soil has warmed and frost danger has passed.

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

San Joaquin County receives only 15" of rain annually. Kidney Beans needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct sow after frost. Allow pods to dry completely on the plant. Kidney beans must be thoroughly cooked as raw or undercooked beans contain harmful lectins.

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 Kidney Beans in San Joaquin County, CA?

San Joaquin County is in Zone 9b with an average last frost of February 4. Plan your Kidney Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Joaquin County, CA?

San Joaquin County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 4 and first fall frost is December 6.

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Your San Joaquin County Garden Planner — Free

A 24-page printable planner built for San Joaquin 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 San Joaquin 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.