When to plant Coreopsis in Madison County, MT
Madison County sits in cold Zone 5a. Plant Coreopsis June 18–July 9 for the single annual harvest; the September 13 first frost closes the window.
When to Plant Coreopsis in Madison County, MT
June to-do list for Madison County, Montana
If you only do a handful of things in the garden this June, make it these. They're sequenced around your zone's frost timing.
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Harden off and plant coreopsis
Your last frost (June 11) has passed. These warm-season crops can handle outdoor soil now.
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Outdoor sowing time: coreopsis
Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.
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.
Madison County, Montana is in USDA Zone 5a. The average last spring frost is June 11 and the first fall frost is September 13, giving you a growing season of approximately 94 days.
At an elevation of 6,394 feet, Madison County receives approximately 20.7 inches of rainfall annually with predominantly loam soil. Summer highs average 80°F, so choose short-season varieties of Coreopsis to ensure they mature before fall.
Madison County Soil Profile
Soil Type
Loam
Soil pH
6.6-8.1
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 Madison County
How your county's soil matches Coreopsis's growing requirements.
Soil pH
Your soil pH (6.6–8.1) overlaps with Coreopsis's range (5.5–7.5), though not a perfect match.
Soil Texture
The loam soil in Madison County is excellent for Coreopsis — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Coreopsis.
Organic Matter
Organic matter is moderate (2.5%). Annual compost additions will help Coreopsis.
How to Plant Coreopsis
Coreopsis Water Budget
Water stress score is 6/10 — 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 | — | 1.5" | 0" | ❄️ Dormant |
| Feb | — | 1.3" | 0" | ❄️ Dormant |
| Mar | — | 2" | 0" | ❄️ Dormant |
| Apr | — | 1.9" | 0" | ❄️ Dormant |
| May | — | 2.3" | 0" | ❄️ Dormant |
| Jun | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Jul | 2.2" | 1.7" | 0.5" | 💧 Light watering |
| Aug | 2.2" | 2.2" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Oct | — | 1.8" | 0" | ❄️ Dormant |
| Nov | — | 1.4" | 0" | ❄️ Dormant |
| Dec | — | 1.3" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Madison 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 — Madison County, MT
Coreopsis Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 9 | Apr 9 – Apr 23 |
| Transplant Outdoors | June 25 | Jun 25 – Jul 9 |
| Direct Sow | June 18 | Jun 18 – Jul 9 |
| Bloom | September 3 | Sep 3 – Dec 10 |
Plant 0.1" deep · 18" apart · Rows 24" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | — |
| June | Transplant Outdoors Direct Sow |
| July | Transplant Outdoors Direct Sow |
| August | — |
| September | Bloom |
| October | Bloom |
| November | Bloom |
| December | Bloom |
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: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
94 days in Madison County
Growing Tips for Coreopsis in Madison County
Direct sow Coreopsis outdoors after June 11 in Madison 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.
Madison County receives only 21" 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 Madison County, MT?
Madison County is in Zone 5a with an average last frost of June 11. Plan your Coreopsis planting based on this frost date — see the calendar above for exact timing.
What planting zone is Madison County, MT?
Madison County, Montana is in USDA Hardiness Zone 5a. The average last spring frost is June 11 and first fall frost is September 13.
When should I plant Coreopsis in Madison County, MT?
In Madison County, MT, plant Coreopsis after the last frost (around June 11) and before the first frost (around September 13). Best results when soil holds above 50°F.
What growing zone is Madison County, MT for Coreopsis?
Madison 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 Madison County's climate?
Yes — Coreopsis grows well in Madison County's temperate climate. Madison County averages a 94-day frost-free season, with last frost around June 11 and first frost around September 13.
Your Madison County Garden Planner — Free
A 22-page printable planner built for Madison 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.