When to Plant Sunflower in Moffat County, CO
Top priorities for Moffat County, Colorado gardeners in May
May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Moffat County, Colorado.
Coming up in June — start thinking about
- Transplants going out: sunflower
- Direct-sowing: sunflower
Sunflowers are tall, cheerful annuals grown for their edible seeds and as pollinator magnets. They come in sizes from 2-foot dwarfs to 12-foot giants.
Moffat County, Colorado is in USDA Zone 5b. The average last spring frost is June 7 and the first fall frost is September 14, giving you a growing season of approximately 99 days.
At an elevation of 6,597 feet, Moffat County receives approximately 12.3 inches of rainfall annually with predominantly loam soil. Summer highs average 86°F, providing good warmth for Sunflower during the growing season. With low rainfall, drip irrigation is essential for growing Sunflower successfully. Mulch heavily to conserve soil moisture.
Moffat County Soil Profile
Soil Type
Loam
Soil pH
6.8-8.3
Drainage
Well Drained
Plant 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 Moffat County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (6.8–8.3) is more alkaline than Sunflower prefers (6.0–7.5). Add sulfur or peat moss to lower pH.
Soil Texture
The loam soil in Moffat County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Drainage
Drainage is adequate for Sunflower.
Organic Matter
Organic matter is moderate (2.4%). Annual compost additions will help Sunflower.
How to Plant Sunflower
Plant Water Budget
Water stress score is 6/10 — consider drought-tolerant varieties and mulching
Monthly Watering Guide for Sunflower
Sunflower 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 | Sunflower Needs | Rainfall | You Supplement | Action |
|---|---|---|---|---|
| Jan | — | 1" | 0" | ❄️ Dormant |
| Feb | — | 0.8" | 0" | ❄️ Dormant |
| Mar | — | 1.1" | 0" | ❄️ Dormant |
| Apr | — | 1.2" | 0" | ❄️ Dormant |
| May | — | 1.4" | 0" | ❄️ Dormant |
| Jun | 2.2" | 0.8" | 1.4" | 🚿 Regular watering |
| Jul | 2.2" | 1" | 1.2" | 🚿 Regular watering |
| Aug | 2.2" | 1.4" | 0.8" | 💧 Light watering |
| Sep | 2.2" | 1.1" | 1.1" | 🚿 Regular watering |
| Oct | — | 1" | 0" | ❄️ Dormant |
| Nov | — | 0.8" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Moffat County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.
Sunflower 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.
Sunflower Planting Timeline — Moffat County, CO
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 12 | Apr 12 – Apr 26 |
| Transplant Outdoors | June 21 | Jun 21 – Jul 5 |
| Direct Sow | June 14 | Jun 14 – Jul 5 |
| Harvest | August 30 | Aug 30 – Oct 18 |
Plant 1" deep · 18" apart · Rows 30" 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 | Harvest |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Only during dry spells
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: too_alkaline
🗺️ USDA Zone
Zone 5b
📆 Growing Season
99 days in Moffat County
Growing Tips for Sunflower in Moffat County
Direct sow Sunflower outdoors after June 07 in Moffat County when soil has warmed and frost danger has passed.
Your 99.0-day growing season in Moffat County is tight for Sunflower (70.0-100.0 days to maturity). Start indoors and choose early-maturing varieties.
Common pests for Sunflower in this region include aphids and slugs. Use row covers early in the season and inspect plants weekly.
Moffat County receives only 12" of rain annually. Sunflower needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.
General growing tips
Direct sow after last frost. Stake tall varieties in windy areas. Harvest seed heads when the back turns brown and seeds are plump. Dry heads upside down.
Companion Planting
Good Companions
Avoid Planting Near
Check more plant combinations with our Companion Planting Checker →
Sunflower in Other Locations
Frequently Asked Questions
When should I plant Sunflower in Moffat County, CO?
Moffat County is in Zone 5b with an average last frost of June 7. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Moffat County, CO?
Moffat County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is June 7 and first fall frost is September 14.
Your Moffat County Garden Planner — Free
A 24-page printable planner built for Moffat County (Zone 5b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.