When to Plant Sunflower in Dolores County, CO
Your May gardening checklist
Your garden in Dolores County, Colorado is working on a schedule, even when you're not. Here's where you should be this May.
A few tasks this May that'll pay off in June
- 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.
Dolores County, Colorado is in USDA Zone 6b. The average last spring frost is June 18 and the first fall frost is September 8, giving you a growing season of approximately 82 days.
At an elevation of 7,506 feet, Dolores County receives approximately 23.1 inches of rainfall annually with predominantly loam soil. Summer highs average 85°F, providing good warmth for Sunflower during the growing season.
Dolores County Soil Profile
Soil Type
Loam
Soil pH
6.3-8.3
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 Dolores County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (6.3–8.3) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Dolores County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is moderate (2.8%). Annual compost additions will help Sunflower.
How to Plant Sunflower
Plant Water Budget
Water stress score is 8/10 — 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 | — | 1.4" | 0" | ❄️ Dormant |
| Feb | — | 1.2" | 0" | ❄️ Dormant |
| Mar | — | 2.1" | 0" | ❄️ Dormant |
| Apr | — | 2.6" | 0" | ❄️ Dormant |
| May | — | 3" | 0" | ❄️ Dormant |
| Jun | 2.2" | 1.8" | 0.4" | 💧 Light watering |
| Jul | 2.2" | 1.9" | 0.3" | 💧 Light watering |
| Aug | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Sep | 2.2" | 2.1" | 0.1" | 💧 Light watering |
| Oct | — | 2.2" | 0" | ❄️ Dormant |
| Nov | — | 1.7" | 0" | ❄️ Dormant |
| Dec | — | 1.2" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Jun–Sep in Dolores 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 — Dolores County, CO
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | April 23 | Apr 23 – May 7 |
| Transplant Outdoors | July 2 | Jul 2 – Jul 16 |
| Direct Sow | June 25 | Jun 25 – Jul 16 |
| Harvest | September 10 | Sep 10 – Oct 29 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | — |
| March | — |
| April | Start Indoors |
| May | Start Indoors |
| June | Direct Sow |
| July | Transplant Outdoors Direct Sow |
| August | — |
| September | Harvest |
| October | Harvest |
| November | — |
| December | — |
Growing Conditions
☀️ Sun
Full Sun (6-8+ hours)
💧 Water
0.5"/week · Natural rainfall sufficient
📅 Days to Maturity
70–100 days
🧪 Soil pH
Needs 6–7.5 · Your soil: acceptable
🗺️ USDA Zone
Zone 6b
📆 Growing Season
82 days in Dolores County
Growing Tips for Sunflower in Dolores County
Direct sow Sunflower outdoors after June 18 in Dolores County when soil has warmed and frost danger has passed.
Your 82.0-day growing season in Dolores 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.
Dolores County receives only 23" 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 Dolores County, CO?
Dolores County is in Zone 6b with an average last frost of June 18. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Dolores County, CO?
Dolores County, Colorado is in USDA Hardiness Zone 6b. The average last spring frost is June 18 and first fall frost is September 8.
Your Dolores County Garden Planner — Free
A 24-page printable planner built for Dolores 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.