When to plant Cosmos in Brown County County,
The best window to plant Cosmos in Brown County County, is April 23–May 14, when soil warms to 50°F. Last frost typically hits April 23; first frost October 11.
When to Plant Cosmos in Brown County, KS
Top priorities for Brown County, Kansas gardeners in June
We've pulled the most time-sensitive tasks for Brown County, Kansas this June and put them front and centre. Tackle them in order.
July will be here before you know it — start on
- First harvests: cosmos
Cosmos (Cosmos bipinnatus) is an airy, feathery-foliaged cottage garden annual from Mexico that thrives on neglect. It produces delicate daisy-like blooms in shades of pink, white, and magenta from midsummer until frost. Cosmos is a prolific self-sower — once established in a garden it often returns year after year without replanting. Excellent habitat plant for beneficial insects.
Brown County, Kansas is in USDA Zone 6a. The average last spring frost is April 23 and the first fall frost is October 11, giving you a growing season of approximately 171 days.
At an elevation of 485 feet, Brown County receives approximately 29.4 inches of rainfall annually with predominantly loam soil. Summer highs average 84°F, so choose short-season varieties of Cosmos to ensure they mature before fall.
Brown County Soil Profile
Soil Type
Loam
Soil pH
6.3-7.8
Drainage
Well Drained
Cosmos 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 Brown County
How your county's soil matches Cosmos's growing requirements.
Soil pH
Your soil pH (6.3–7.8) is within Cosmos's preferred range (6.0–8.0).
Soil Texture
The loam soil in Brown County is excellent for Cosmos — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Cosmos.
Organic Matter
Organic matter is moderate (3.7%). Annual compost additions will help Cosmos.
How to Plant Cosmos
Succession Planting Cosmos
Sow every 6.9 weeks. Last sowing by Jul 13 to harvest before frost.
Cosmos Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Cosmos
Cosmos 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 | Cosmos Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 0.7" | 0" | ❄️ Dormant |
| Feb | — | 1" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.7" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 5.2" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.9" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 3.3" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Nov | — | 1.1" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Brown County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Cosmos 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.
Cosmos Planting Timeline — Brown County, KS
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | March 26 | Mar 26 – Apr 9 |
| Transplant Outdoors | April 23 | Apr 23 – May 7 |
| Direct Sow | April 23 | Apr 23 – May 14 |
| Bloom | July 2 | Jul 2 – Oct 8 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | Start Indoors |
| April | Start Indoors Transplant Outdoors Direct Sow |
| 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
60–90 days
🧪 Soil pH
Needs 6–8 · Your soil: ideal
🗺️ USDA Zone
Zone 6a
📆 Growing Season
171 days in Brown County
Growing Tips for Cosmos in Brown County
Direct sow Cosmos outdoors after April 23 in Brown County when soil has warmed and frost danger has passed.
Common pests for Cosmos in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
General growing tips
Direct-sow after last frost; cosmos germinates readily at 65-80°F in 7-10 days. Avoid rich soil — excess fertility produces lush foliage at the expense of blooms. Cosmos tolerates poor, dry soil exceptionally well. Pinch seedlings at 8 inches to encourage branching. Self-sows freely; allow some seed heads to mature and drop for a no-fuss perennial effect in warm climates.
Companion Planting
Good Companions
Check more plant combinations with our Companion Planting Checker →
Cosmos in Other Locations
Frequently Asked Questions
When should I plant Cosmos in Brown County, KS?
Brown County is in Zone 6a with an average last frost of April 23. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Brown County, KS?
Brown County, Kansas is in USDA Hardiness Zone 6a. The average last spring frost is April 23 and first fall frost is October 11.
When should I plant Cosmos in Brown County County, ?
In Brown County County, , plant Cosmos after the last frost (around April 23) and before the first frost (around October 11). Best results when soil holds above 50°F.
What growing zone is Brown County County, for Cosmos?
Brown County County sits in USDA Zone 6a. Cosmos grows reliably in zones 2a through 11b, so it's a good fit here.
Can Cosmos grow in Brown County County's climate?
Yes — Cosmos grows well in Brown County County's temperate climate. Brown County County averages a 171-day frost-free season, with last frost around April 23 and first frost around October 11.
Your Brown County Garden Planner — Free
A 22-page printable planner built for Brown County (Zone 6a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.