When to Plant Cosmos in Yoder, WY
June in the garden — Goshen County, Wyoming
A quick June briefing for Goshen County, Wyoming gardeners — what's urgent, what's next, and what can wait.
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Sow cosmos in trays indoors
These need a head start before your last frost (May 13). Sow into cells now so you're ready to transplant in a few weeks.
A few tasks this June that'll pay off in July
- 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.
Yoder, Wyoming is in USDA Zone 5a. The average last spring frost is May 13 and the first fall frost is September 29, giving you a growing season of approximately 139 days.
At an elevation of 5,820 feet, Goshen County receives approximately 15.7 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. With low rainfall, drip irrigation is essential for growing Cosmos successfully. Mulch heavily to conserve soil moisture.
Yoder Soil Profile
Soil Type
Loam
Soil pH
6.7-8.4
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 Yoder
How your county's soil matches Cosmos's growing requirements.
Soil pH
Your soil pH (6.7–8.4) overlaps with Cosmos's range (6.0–8.0), though not a perfect match.
Soil Texture
The loam soil in Goshen County is excellent for Cosmos — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.9%). Annual compost additions will help Cosmos.
How to Plant Cosmos
Succession Planting Cosmos
Sow every 6.9 weeks. Last sowing by Jul 01 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 | — | 1.2" | 0" | ❄️ Dormant |
| Feb | — | 1" | 0" | ❄️ Dormant |
| Mar | — | 1.6" | 0" | ❄️ Dormant |
| Apr | — | 1.6" | 0" | ❄️ Dormant |
| May | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Jun | 2.2" | 1.1" | 1.1" | 🚿 Regular watering |
| Jul | 2.2" | 1.3" | 0.9" | 💧 Light watering |
| Aug | 2.2" | 1.5" | 0.7" | 💧 Light watering |
| Sep | 2.2" | 1.1" | 1.1" | 🚿 Regular watering |
| Oct | — | 1.5" | 0" | ❄️ Dormant |
| Nov | — | 1.2" | 0" | ❄️ Dormant |
| Dec | — | 1" | 0" | ❄️ Dormant |
Water needs are for active growing months only (May–Sep in Goshen 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 — Yoder, WY
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 15 | Apr 15 – Apr 29 |
| Transplant Outdoors | May 20 | May 20 – Jun 3 |
| Direct Sow | May 20 | May 20 – Jun 10 |
| Bloom | July 29 | Jul 29 – Oct 21 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Transplant Outdoors Direct Sow |
| June | Transplant Outdoors Direct Sow |
| July | Bloom |
| August | Bloom |
| September | Bloom |
| October | Bloom |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Only during dry spells
📅 Days to Maturity
60–90 days
🧪 Soil pH
Needs 6–8 · Your soil: acceptable
🗺️ USDA Zone
Zone 5a
📆 Growing Season
139 days in Goshen County
Growing Tips for Cosmos in Yoder
Direct sow Cosmos outdoors after May 13 in Goshen 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.
Goshen County receives only 16" of rain annually. Cosmos needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
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
Your Goshen County Garden Planner — Free
A 22-page printable planner built for Goshen 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.