When to Plant Sunflower in Allen County, KS
Top priorities for Allen County, Kansas gardeners in May
We've pulled the most time-sensitive tasks for Allen County, Kansas this May and put them front and centre. Tackle them in order.
Before June arrives, get these ready
- Starting indoors: 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.
Allen County, Kansas is in USDA Zone 6b. The average last spring frost is April 8 and the first fall frost is October 25, giving you a growing season of approximately 200 days.
At an elevation of 578 feet, Allen County receives approximately 26.6 inches of rainfall annually with predominantly loam soil. Summer highs average 88°F, providing good warmth for Sunflower during the growing season.
Allen County Soil Profile
Soil Type
Loam
Soil pH
6.5-7.8
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 Allen County
How your county's soil matches Sunflower's growing requirements.
Soil pH
Your soil pH (6.5–7.8) overlaps with Sunflower's range (6.0–7.5), though not a perfect match.
Soil Texture
The loam soil in Allen County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.
Organic Matter
Organic matter is excellent (4.1%) — Sunflower will thrive.
How to Plant Sunflower
Succession Planting Sunflower
Sow every 8 weeks. Last sowing by Jul 17 to harvest before frost.
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 | — | 0.7" | 0" | ❄️ Dormant |
| Feb | — | 1" | 0" | ❄️ Dormant |
| Mar | — | 1.5" | 0" | ❄️ Dormant |
| Apr | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| May | 2.2" | 4.1" | 0" | ✅ Rainfall sufficient |
| Jun | 2.2" | 4.9" | 0" | ✅ Rainfall sufficient |
| Jul | 2.2" | 3.6" | 0" | ✅ Rainfall sufficient |
| Aug | 2.2" | 2.7" | 0" | ✅ Rainfall sufficient |
| Sep | 2.2" | 2.2" | 0" | ✅ Rainfall sufficient |
| Oct | 2.2" | 1.6" | 0.6" | 💧 Light watering |
| Nov | — | 0.8" | 0" | ❄️ Dormant |
| Dec | — | 0.8" | 0" | ❄️ Dormant |
Water needs are for active growing months only (Apr–Oct in Allen 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 — Allen County, KS
Sunflower Planting Calendar
| Activity | When | Date Range |
|---|---|---|
| Start Indoors | February 11 | Feb 11 – Feb 25 |
| Transplant Outdoors | April 22 | Apr 22 – May 6 |
| Direct Sow | April 15 | Apr 15 – May 6 |
| Harvest | July 1 | Jul 1 – Aug 19 |
Plant 1" deep · 18" apart · Rows 30" apart
Month-by-Month Timeline
| Month | Activities |
|---|---|
| January | — |
| February | Start Indoors |
| March | — |
| April | Transplant Outdoors Direct Sow |
| May | Transplant Outdoors Direct Sow |
| June | — |
| July | Harvest |
| August | Harvest |
| September | — |
| October | — |
| 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
200 days in Allen County
Growing Tips for Sunflower in Allen County
Direct sow Sunflower outdoors after April 08 in Allen County when soil has warmed and frost danger has passed.
Common pests for Sunflower 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. 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 Allen County, KS?
Allen County is in Zone 6b with an average last frost of April 8. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.
What planting zone is Allen County, KS?
Allen County, Kansas is in USDA Hardiness Zone 6b. The average last spring frost is April 8 and first fall frost is October 25.
Your Allen County Garden Planner — Free
A 24-page printable planner built for Allen 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.