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When to plant Cosmos in Phillips County County,

The best window to plant Cosmos in Phillips County County, is April 29–May 20, when soil warms to 50°F. Last frost typically hits April 29; first frost October 10.

When to Plant Cosmos in Phillips County, KS

Phillips County, Kansas Zone 6a June

June to-do list for Phillips County, Kansas

Each item below is timed to Phillips County, Kansas's frost dates and soil temperatures. Skip nothing, stress about nothing.

Avg. last frost April 29
Avg. first frost October 10
Soil temp (4") 70°F
Watering Low
Pest pressure High
Daylight 14.8 hrs
Coming up in July — start thinking about
  • First harvests: cosmos

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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.

Phillips County, Kansas is in USDA Zone 6a. The average last spring frost is April 29 and the first fall frost is October 10, giving you a growing season of approximately 164 days.

At an elevation of 929 feet, Phillips County receives approximately 32.1 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.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Phillips County, KS (Zone 6a) Moderate season
164 days
Last Spring Frost April 29
164 growing days
First Fall Frost October 10
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Phillips County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.5

Drainage

Well Drained

Cosmos Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 25 Transplant: Apr 22 🌸 Bloom: Jul 1 – Oct 7
Recommended (50%) ✗ May not fit
Start indoors: Apr 1 Transplant: Apr 29 🌸 Bloom: Jul 8 – Oct 14
Safe Start (90%) ✗ May not fit
Start indoors: Apr 15 Transplant: May 13 🌸 Bloom: Jul 22 – Oct 28

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 Phillips County

How your county's soil matches Cosmos's growing requirements.

Soil pH

Your soil pH (6.7–7.5) is within Cosmos's preferred range (6.0–8.0).

Soil Texture

The loam soil in Phillips County is excellent for Cosmos — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is excellent (4.3%) — Cosmos will thrive.

How to Plant Cosmos

0.3"
Planting Depth
12"
Between Plants
18"
Between Rows

Succession Planting Cosmos

3
successive plantings in your 164-day season

Sow every 6.9 weeks. Last sowing by Jul 12 to harvest before frost.

Cosmos Water Budget

Plant needs
0.5″/week
Rainfall provides
0.8″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — 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 0.9" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 2.2" 0" ❄️ Dormant
Apr 2.2" 3.8" 0" ✅ Rainfall sufficient
May 2.2" 5.1" 0" ✅ Rainfall sufficient
Jun 2.2" 5.4" 0" ✅ Rainfall sufficient
Jul 2.2" 3.8" 0" ✅ Rainfall sufficient
Aug 2.2" 3.2" 0" ✅ Rainfall sufficient
Sep 2.2" 3" 0" ✅ Rainfall sufficient
Oct 2.2" 1.7" 0.5" 💧 Light watering
Nov 1.1" 0" ❄️ Dormant
Dec 0.8" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Phillips 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 needs ~975 GDD — county provides 2,132 GDD Excellent fit

Cosmos Planting Timeline — Phillips County, KS

Cosmos Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 – Apr 15
Transplant Outdoors April 29 Apr 29 – May 13
Direct Sow April 29 Apr 29 – May 20
Bloom July 8 Jul 8 – Oct 14

Plant 0.3" deep · 12" apart · Rows 18" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors Transplant Outdoors Direct Sow
May Transplant Outdoors Direct Sow
June
July Bloom
August Bloom
September Bloom
October Bloom
November
December
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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

164 days in Phillips County

Growing Tips for Cosmos in Phillips County

Direct sow Cosmos outdoors after April 29 in Phillips 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 →

Frequently Asked Questions

When should I plant Cosmos in Phillips County, KS?

Phillips County is in Zone 6a with an average last frost of April 29. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.

What planting zone is Phillips County, KS?

Phillips County, Kansas is in USDA Hardiness Zone 6a. The average last spring frost is April 29 and first fall frost is October 10.

When should I plant Cosmos in Phillips County County, ?

In Phillips County County, , plant Cosmos after the last frost (around April 29) and before the first frost (around October 10). Best results when soil holds above 50°F.

What growing zone is Phillips County County, for Cosmos?

Phillips 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 Phillips County County's climate?

Yes — Cosmos grows well in Phillips County County's temperate climate. Phillips County County averages a 164-day frost-free season, with last frost around April 29 and first frost around October 10.

🌱

Your Phillips County Garden Planner — Free

A 22-page printable planner built for Phillips 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.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Phillips County, KS. Local conditions may vary. Last updated: June 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.