When to plant Coreopsis in Merced County, CA
Spring Coreopsis in Merced County goes in February 10–March 3, once nighttime temps stop dipping near freezing.
When to Plant Coreopsis in Merced County, CA
July in the garden — Merced County, California
If you only do a handful of things in the garden this July, make it these. They're sequenced around your zone's frost timing.
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It's harvest week for coreopsis
Morning harvests are best — cooler temperatures mean crisper produce and longer fridge life.
To set up a strong August, finish these tasks
- First harvests: coreopsis
Coreopsis (Tickseed) is a cheerful, long-blooming native perennial that produces a continuous flush of bright yellow, gold, or bi-colored daisy-like flowers from early summer well into fall. One of the most reliable cut-and-come-again bloomers in the perennial garden, it thrives in hot, dry, sunny conditions and poor soil where many competitors struggle. An invaluable nectar source for native bees and butterflies, and a butterfly host plant for several species.
Merced County, California is in USDA Zone 9a. The average last spring frost is February 24 and the first fall frost is November 28, giving you a growing season of approximately 277 days.
At an elevation of 269 feet, Merced County receives approximately 18.8 inches of rainfall annually with predominantly loam soil. Summer highs average 87°F, providing good warmth for Coreopsis during the growing season. With low rainfall, drip irrigation is essential for growing Coreopsis successfully. Mulch heavily to conserve soil moisture.
Merced County Soil Profile
Soil Type
Loam
Soil pH
6.8-7.7
Drainage
Well Drained
Coreopsis 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 Merced County
How your county's soil matches Coreopsis's growing requirements.
Soil pH
Your soil pH (6.8–7.7) overlaps with Coreopsis's range (5.5–7.5), though not a perfect match.
Soil Texture
The loam soil in Merced County is excellent for Coreopsis — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.6%). Annual compost additions will help Coreopsis.
How to Plant Coreopsis
Succession Planting Coreopsis
Sow every 6.9 weeks. Last sowing by Sep 09 to harvest before frost.
Coreopsis Water Budget
Water stress score is 8/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Coreopsis
Coreopsis 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 | Coreopsis Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 4.4" | 0" | ❄️ Dormant |
| Feb | 2.2" | 4" | 0" | ✅ Rainfall sufficient |
| Mar | 2.2" | 2.6" | 0" | ✅ Rainfall sufficient |
| Apr | 2.2" | 1.7" | 0.5" | 💧 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" | 0.7" | 1.5" | 🚿 Regular watering |
| Nov | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Dec | — | 3.1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Feb–Nov in Merced County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Coreopsis 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.
Coreopsis Planting Timeline — Merced County, CA
Coreopsis Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | December 30 | Dec 30 – Jan 13 |
| Transplant Outdoors | February 10 | Feb 10 – Feb 24 |
| Direct Sow | February 10 | Feb 10 – Mar 3 |
| Bloom | April 7 | Apr 7 – Sep 8 |
Plant 0.1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | Start Indoors |
| February | Transplant Outdoors Direct Sow |
| March | Direct Sow |
| April | Bloom |
| May | Bloom |
| June | Bloom |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | — |
| November | — |
| December | Start Indoors |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Only during dry spells
📅 Days to Maturity
60–80 days
🧪 Soil pH
Needs 5.5–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 9a
📆 Growing Season
277 days in Merced County
Growing Tips for Coreopsis in Merced County
Direct sow Coreopsis outdoors after February 24 in Merced County when soil has warmed and frost danger has passed.
Common pests for Coreopsis in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
Merced County receives only 19" of rain annually. Coreopsis needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Start seeds indoors 8–10 weeks before last frost or direct sow after last frost. Seeds germinate easily without stratification. Thrives in poor to average, well-drained soil — rich soil promotes foliage over flowers. Drought tolerant once established; overwatering is the most common mistake. Deadhead spent blooms to maintain continuous flowering through the season. Shear plants by one-third in midsummer for a fresh flush of late-season blooms. Year 2+ plants bloom most heavily. Divide every 2–3 years in early spring to rejuvenate crowded clumps.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Coreopsis in Other Locations
Frequently Asked Questions
When should I plant Coreopsis in Merced County, CA?
Merced County is in Zone 9a with an average last frost of February 24. Plan your Coreopsis planting based on this frost date — see the calendar above for exact timing.
What planting zone is Merced County, CA?
Merced County, California is in USDA Hardiness Zone 9a. The average last spring frost is February 24 and first fall frost is November 28.
When should I plant Coreopsis in Merced County, CA?
In Merced County, CA, plant Coreopsis after the last frost (around February 24) and before the first frost (around November 28). Best results when soil holds above 50°F.
What growing zone is Merced County, CA for Coreopsis?
Merced County sits in USDA Zone 9a. Coreopsis grows reliably in zones 3a through 9b, so it's a good fit here.
Can Coreopsis grow in Merced County's climate?
Yes — Coreopsis grows well in Merced County's temperate climate. Merced County averages a 278-day frost-free season, with last frost around February 24 and first frost around November 28.
Your Merced County Garden Planner — Free
A 22-page printable planner built for Merced County (Zone 9a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.