When to Plant Kidney Beans in San Mateo County, CA
Your May gardening checklist
A quick May briefing for San Mateo County, California gardeners — what's urgent, what's next, and what can wait.
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Bring in the kidney beans
If you can't use it all right away, check the food-preservation section of your planner.
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 Mateo County, California is in USDA Zone 10a. The average last spring frost is January 18 and the first fall frost is December 12, giving you a growing season of approximately 328 days.
At an elevation of 277 feet, San Mateo County receives approximately 16.9 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Kidney Beans to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Kidney Beans successfully. Mulch heavily to conserve soil moisture.
San Mateo County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.2
Drainage
Well Drained
Plant Planting Risk Windows
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 Mateo County
How your county's soil matches Kidney Beans's growing requirements.
Soil pH
Your soil pH (6.8–7.2) is within Kidney Beans's preferred range (6.0–7.5).
Soil Texture
The loam soil in San Mateo County is excellent for Kidney Beans — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Kidney Beans.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Kidney Beans.
How to Plant Kidney Beans
Plant Water Budget
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 | 4.3" | 3.9" | 0.4" | 💧 Light watering |
| Feb | 4.3" | 3.4" | 0.9" | 💧 Light watering |
| Mar | 4.3" | 2.7" | 1.6" | 💧 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" | 1.4" | 2.9" | 🚿 Regular watering |
| Dec | 4.3" | 2.9" | 1.4" | 💧 Light watering |
Water needs are for active growing months only (Jan–Dec in San Mateo 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 Planting Timeline — San Mateo County, CA
Kidney Beans Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Direct Sow | January 25 | Jan 25 – Feb 15 |
| Harvest | April 26 | Apr 26 – May 31 |
Plant 1" deep · 15" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Direct Sow |
| February | Direct Sow |
| March | — |
| April | Harvest |
| May | Harvest |
| June | — |
| July | — |
| August | — |
| September | — |
| October | — |
| November | — |
| December | — |
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: ideal
🗺️ USDA Zone
Zone 10a
📆 Growing Season
328 days in San Mateo County
Growing Tips for Kidney Beans in San Mateo County
Direct sow Kidney Beans outdoors after January 18 in San Mateo 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 Mateo County receives only 17" 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
Check more plant combinations with our Companion Planting Checker →
Kidney Beans in Other Locations
Frequently Asked Questions
When should I plant Kidney Beans in San Mateo County, CA?
San Mateo County is in Zone 10a with an average last frost of January 18. Plan your Kidney Beans planting based on this frost date — see the calendar above for exact timing.
What planting zone is San Mateo County, CA?
San Mateo County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 18 and first fall frost is December 12.
Your San Mateo County Garden Planner — Free
A 24-page printable planner built for San Mateo County (Zone 10a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.