When to plant Coreopsis in Calhoun County County,
Coreopsis planted in Calhoun County County between May 2 and May 23 matures in 80 days — well before the October 6 first frost.
When to Plant Coreopsis in Calhoun County, IA
Your June game plan for Calhoun County, Iowa
Each item below is timed to Calhoun County, Iowa's frost dates and soil temperatures. Skip nothing, stress about nothing.
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Fire up the seed-starting tray: coreopsis
Your window is short. These crops want several weeks of indoor growth before they go outside.
A few tasks this June that'll pay off in July
- 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.
Calhoun County, Iowa is in USDA Zone 5a. The average last spring frost is April 25 and the first fall frost is October 6, giving you a growing season of approximately 164 days.
At an elevation of 1,052 feet, Calhoun County receives approximately 30.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 82°F, so choose short-season varieties of Coreopsis to ensure they mature before fall.
Calhoun County Soil Profile
Soil Type
Silt Loam
Soil pH
5.8-6.8
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 Calhoun County
How your county's soil matches Coreopsis's growing requirements.
Soil pH
Your soil pH (5.8–6.8) is within Coreopsis's preferred range (5.5–7.5).
Soil Texture
The silt loam soil in Calhoun County is excellent for Coreopsis — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.5%) — Coreopsis will thrive.
How to Plant Coreopsis
Succession Planting Coreopsis
Sow every 6.9 weeks. Last sowing by Jul 18 to harvest before frost.
Coreopsis Water Budget
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 | — | 1.2" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 2.3" | 0" | ❄️ Dormant |
| Apr | 2.2" | 3.2" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 3.4" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 2.9" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.5" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.4" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Nov | — | 2.3" | 0" | ❄️ Dormant |
| Dec | — | 1.7" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Calhoun 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 — Calhoun County, IA
Coreopsis Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 21 | Feb 21 – Mar 7 |
| Transplant Outdoors | May 9 | May 9 – May 23 |
| Direct Sow | May 2 | May 2 – May 23 |
| Bloom | July 18 | Jul 18 – Oct 24 |
Plant 0.1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | Start Indoors |
| April | — |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
60–80 days
🧪 Soil pH
Needs 5.5–7.5 · Your soil: ideal
🗺️ USDA Zone
Zone 5a
📆 Growing Season
164 days in Calhoun County
Growing Tips for Coreopsis in Calhoun County
Direct sow Coreopsis outdoors after April 25 in Calhoun 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.
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 Calhoun County, IA?
Calhoun County is in Zone 5a with an average last frost of April 25. Plan your Coreopsis planting based on this frost date — see the calendar above for exact timing.
What planting zone is Calhoun County, IA?
Calhoun County, Iowa is in USDA Hardiness Zone 5a. The average last spring frost is April 25 and first fall frost is October 6.
When should I plant Coreopsis in Calhoun County, ?
In Calhoun County, , plant Coreopsis after the last frost (around April 25) and before the first frost (around October 6). Best results when soil holds above 50°F.
What growing zone is Calhoun County, for Coreopsis?
Calhoun County sits in USDA Zone 5a. Coreopsis grows reliably in zones 3a through 9b, so it's a good fit here.
Can Coreopsis grow in Calhoun County's climate?
Yes — Coreopsis grows well in Calhoun County's temperate climate. Calhoun County averages a 164-day frost-free season, with last frost around April 25 and first frost around October 6.
Your Calhoun County Garden Planner — Free
A 22-page printable planner built for Calhoun County (Zone 5a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.