When to plant Calendula in Alameda County County,
Plant Calendula in Alameda County County, when soil hits 50°F — usually November 9. Continue planting through November 30 for the spring crop. A second sowing from September 5 to September 19 extends the harvest into fall.
When to Plant Calendula in Alameda County, CA
What to do in June
Each item below is timed to Alameda County, California's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Survive, don't thrive
June-August is endurance gardening. Keep okra, peppers, sweet potatoes, and southern peas alive. Harvest everything daily before the heat damages produce on the vine.
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Start fall tomato seeds indoors
Yes, indoors — under lights or in AC. They'll be ready to transplant in August when temperatures briefly moderate.
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Add compost to empty beds
Empty beds get a thick layer of compost + mulch to suppress weeds and feed the soil for fall planting.
Calendula (Calendula officinalis) is a cheerful, edible-flowered cool-season annual valued by herbalists, chefs, and gardeners alike. Its golden-orange petals are used in salves, teas, and as a saffron substitute. Hardy enough to tolerate light frosts, it blooms prolifically in spring and fall, taking a pause during the hottest weeks of summer.
Alameda 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 379 feet, Alameda County receives approximately 16.4 inches of rainfall annually with predominantly loam soil. Summer highs average 97°F, so Calendula may need afternoon shade and extra watering during peak heat. With low rainfall, drip irrigation is essential for growing Calendula successfully. Mulch heavily to conserve soil moisture.
Alameda County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.7
Drainage
Well Drained
Calendula 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 Alameda County
How your county's soil matches Calendula's growing requirements.
Soil pH
Your soil pH (6.3–7.7) overlaps with Calendula's range (5.5–7.0), though not a perfect match.
Soil Texture
The loam soil in Alameda County is excellent for Calendula — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (3.0%). Annual compost additions will help Calendula.
How to Plant Calendula
Fall planting: Sow 14 weeks before your first frost date for a fall harvest.
Succession Planting Calendula
Sow every 5.7 weeks. Last sowing by Oct 03 to harvest before frost.
For a dedicated fall crop, sow by Sep 05.
Calendula Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Calendula
Calendula needs approximately 0.5 inches of water per week (2.2" per month). Here's how your county's rainfall compares month by month.
| Month | Calendula Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | 2.2" | 3" | 0" | ✅ Rainfall sufficient |
| Feb | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 1.2" | 1" | 💧 Light watering |
| May | 2.2" | 0.4" | 1.8" | 🚿 Regular watering |
| Jun | 2.2" | 0.1" | 2.1" | 🚿 Regular watering |
| Jul | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Aug | 2.2" | 0" | 2.2" | 🚿 Regular watering |
| Sep | 2.2" | 0.2" | 2" | 🚿 Regular watering |
| Oct | 2.2" | 0.6" | 1.6" | 🚿 Regular watering |
| Nov | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Dec | 2.2" | 3.1" | 0" | ✅ Rainfall sufficient |
Water needs are for active growing months only (Jan–Dec in Alameda County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Calendula 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.
Calendula Planting Timeline — Alameda County, CA
Calendula Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Transplant Outdoors | December 7 | Dec 7 – Dec 21 |
| Direct Sow | November 9 | Nov 9 – Nov 30 |
| Bloom | January 18 | Jan 18 – Apr 26 |
| Fall Sowing | September 5 | Sep 5 – Sep 19 |
Plant 0.3" deep · 9" apart · Rows 12" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Bloom |
| February | Bloom |
| March | Bloom |
| April | Bloom |
| May | — |
| June | — |
| July | — |
| August | — |
| September | Fall Sowing |
| October | — |
| November | Direct Sow |
| December | Transplant Outdoors |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · 1-2 times/week
📅 Days to Maturity
50–70 days
🧪 Soil pH
Needs 5.5–7 · Your soil: acceptable
🗺️ USDA Zone
Zone 10a
📆 Growing Season
328 days in Alameda County
Growing Tips for Calendula in Alameda County
Direct sow Calendula outdoors after January 18 in Alameda County when soil has warmed and frost danger has passed.
With summer highs reaching 97°F in Alameda County, provide afternoon shade for Calendula and water deeply in the morning.
Common pests for Calendula in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
Alameda County receives only 16" of rain annually. Calendula needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct-sow in early spring as soon as soil can be worked — seeds germinate in cool soil (50-65°F). In zones 7+, also sow in fall for winter/spring bloom. Deadhead consistently to extend bloom. Plants self-seed readily; save a few spent heads and allow them to drop. Harvest petals when flowers are fully open for best flavor and medicinal value.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Calendula in Other Locations
Frequently Asked Questions
When should I plant Calendula in Alameda County, CA?
Alameda County is in Zone 10a with an average last frost of January 18. Plan your Calendula planting based on this frost date — see the calendar above for exact timing.
What planting zone is Alameda County, CA?
Alameda County, California is in USDA Hardiness Zone 10a. The average last spring frost is January 18 and first fall frost is December 12.
When should I plant Calendula in Alameda County County, ?
In Alameda County County, , plant Calendula after the last frost (around January 18) and before the first frost (around December 12). Best results when soil holds above 50°F.
What growing zone is Alameda County County, for Calendula?
Alameda County County sits in USDA Zone 10a. Calendula grows reliably in zones 2a through 11b, so it's a good fit here.
Can Calendula grow in Alameda County County's climate?
Yes — Calendula grows well in Alameda County County's temperate climate. Alameda County County averages a 329-day frost-free season, with last frost around January 18 and first frost around December 12.
Your Alameda County Garden Planner — Free
A 22-page printable planner built for Alameda 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.