When to Plant Quince in Contra Costa County, CA
What to do in May
A quick May briefing for Contra Costa County, California gardeners — what's urgent, what's next, and what can wait.
Quince is a small ornamental tree producing fragrant, golden fruits that are too hard and astringent to eat raw but transform into a beautiful rose-colored paste when cooked.
Contra Costa County, California is in USDA Zone 9b. The average last spring frost is February 26 and the first fall frost is November 29, giving you a growing season of approximately 276 days.
At an elevation of 88 feet, Contra Costa County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Quince during the growing season. With low rainfall, drip irrigation is essential for growing Quince successfully. Mulch heavily to conserve soil moisture.
Contra Costa County Soil Profile
Soil Type
Loam
Soil pH
6.7-7.8
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 Contra Costa County
How your county's soil matches Quince's growing requirements.
Soil pH
Your soil pH (6.7–7.8) overlaps with Quince's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Contra Costa County is excellent for Quince — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Quince.
How to Plant Quince
Plant Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Quince
Quince needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.
| Month | Quince Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 4.1" | 0" | ❄️ Dormant |
| Feb | 4.3" | 4.5" | 0" | ✅ Rainfall sufficient |
| Mar | 4.3" | 3" | 1.3" | 💧 Light watering |
| Apr | 4.3" | 1.5" | 2.8" | 🚿 Regular watering |
| May | 4.3" | 0.6" | 3.7" | 🚿 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" | 1.6" | 2.7" | 🚿 Regular watering |
| Dec | — | 2.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Contra Costa County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Quince 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.
Quince Planting Timeline — Contra Costa County, CA
Quince Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | March 12 | Mar 12 – Mar 26 |
· 120" apart · Rows 144" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Transplant Outdoors |
| April | — |
| May | — |
| 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
1095–1825 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 9b
📆 Growing Season
276 days in Contra Costa County
Growing Tips for Quince in Contra Costa County
Direct sow Quince outdoors after February 26 in Contra Costa County when soil has warmed and frost danger has passed.
Your 277.0-day growing season in Contra Costa County is tight for Quince (1095.0-1825.0 days to maturity). Start indoors and choose early-maturing varieties.
Contra Costa County receives only 19" of rain annually. Quince needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Plant in well-drained soil in a warm, sheltered location. Quince is self-fertile. Harvest after frost when fruit is golden and fragrant. Fire blight can be an issue; choose resistant varieties.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Quince in Other Locations
Frequently Asked Questions
When should I plant Quince in Contra Costa County, CA?
Contra Costa County is in Zone 9b with an average last frost of February 26. Plan your Quince planting based on this frost date — see the calendar above for exact timing.
What planting zone is Contra Costa County, CA?
Contra Costa County, California is in USDA Hardiness Zone 9b. The average last spring frost is February 26 and first fall frost is November 29.
Your Contra Costa County Garden Planner — Free
A 24-page printable planner built for Contra Costa 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.