When to Plant Cosmos in Klamath County, OR
June in the garden — Klamath County, Oregon
Here's what deserves your attention in Klamath County, Oregon this month. Everything below is tailored to Zone 6b and timed around your local frost dates.
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Time to transplant cosmos
Plant tomatoes deep — bury the stem up to the first true leaves to grow extra roots. Everything else goes in at the same depth it grew in the tray.
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Scatter cosmos into prepared beds
Thin ruthlessly once seedlings are up. Crowded roots mean smaller crops from every plant.
Get ahead of July
- Starting indoors: 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.
Klamath County, Oregon is in USDA Zone 6b. The average last spring frost is June 13 and the first fall frost is September 21, giving you a growing season of approximately 100 days.
At an elevation of 142 feet, Klamath County receives approximately 48.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 83°F, so choose short-season varieties of Cosmos to ensure they mature before fall.
Klamath County Soil Profile
Soil Type
Silt Loam
Soil pH
5.5-6.3
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 Klamath County
How your county's soil matches Cosmos's growing requirements.
Soil pH
Your soil pH (5.5–6.3) is more acidic than Cosmos prefers (6.0–8.0). Add garden lime to raise pH.
Soil Texture
The silt loam soil in Klamath County is excellent for Cosmos — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Cosmos.
Organic Matter
Organic matter is excellent (5.1%) — Cosmos will thrive.
How to Plant Cosmos
Cosmos Water Budget
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 | — | 7.4" | 0" | ❄️ Dormant |
| Feb | — | 5.2" | 0" | ❄️ Dormant |
| Mar | — | 4.8" | 0" | ❄️ Dormant |
| Apr | — | 3.3" | 0" | ❄️ Dormant |
| May | — | 3" | 0" | ❄️ Dormant |
| Jun | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Jul | 2.2" | 0.9" | 1.3" | 🚿 Regular watering |
| Aug | 2.2" | 0.8" | 1.4" | 🚿 Regular watering |
| Sep | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Oct | — | 4.8" | 0" | ❄️ Dormant |
| Nov | — | 7.7" | 0" | ❄️ Dormant |
| Dec | — | 6.9" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Klamath 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 — Klamath County, OR
Cosmos Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | May 16 | May 16 – May 30 |
| Transplant Outdoors | June 13 | Jun 13 – Jun 27 |
| Direct Sow | June 13 | Jun 13 – Jul 4 |
| Bloom | August 22 | Aug 22 – Dec 5 |
Plant 0.3" deep · 12" apart · Rows 18" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | — |
| May | Start Indoors |
| June | Transplant Outdoors Direct Sow |
| July | Direct Sow |
| August | Bloom |
| 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
60–90 days
🧪 Soil pH
Needs 6–8 · Your soil: too_acidic
🗺️ USDA Zone
Zone 6b
📆 Growing Season
100 days in Klamath County
Growing Tips for Cosmos in Klamath County
Direct sow Cosmos outdoors after June 13 in Klamath County when soil has warmed and frost danger has passed.
Your 100.0-day growing season in Klamath County is tight for Cosmos (60.0-90.0 days to maturity). Start indoors and choose early-maturing varieties.
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 Klamath County, OR?
Klamath County is in Zone 6b with an average last frost of June 13. Plan your Cosmos planting based on this frost date — see the calendar above for exact timing.
What planting zone is Klamath County, OR?
Klamath County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is June 13 and first fall frost is September 21.
Your Klamath County Garden Planner — Free
A 22-page printable planner built for Klamath County (Zone 6b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.