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When to Plant Sunflower in Yoder, WY

Yoder, WY Zone 5a June

Yoder, WY gardeners: here's your June plan

We've pulled the most time-sensitive tasks for Yoder, WY this June and put them front and centre. Tackle them in order.

Avg. last frost May 13
Avg. first frost September 29
Soil temp (4") 52°F
Watering Critical
Pest pressure High
Daylight 15.1 hrs
  1. Start sunflower under lights

    A seed-starting mix and a sunny window (or a grow light) are all you need. Keep soil warm — around 70°F — for fast germination.

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Sunflower (Helianthus annuus) is a fast-growing North American native annual famous for its towering stems and brilliant yellow heads. It thrives in full sun and heat, producing large, pollen-rich blooms that attract bees, butterflies, and seed-eating birds. Varieties range from 18-inch dwarfs to 12-foot giants and nearly every color except blue.

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 Sunflower to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Sunflower successfully. Mulch heavily to conserve soil moisture.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Yoder, WY (Zone 5a) Short season
139 days
Last Spring Frost May 13
139 growing days
First Fall Frost September 29

Yoder Soil Profile

Soil Type

Loam

Soil pH

6.7-8.4

Drainage

Well Drained

Sunflower Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 19 Transplant: May 17 🌸 Bloom: Aug 9 – Oct 18
Recommended (50%) ✗ May not fit
Start indoors: Apr 22 Transplant: May 20 🌸 Bloom: Aug 12 – Oct 21
Safe Start (90%) ✗ May not fit
Start indoors: May 3 Transplant: May 31 🌸 Bloom: Aug 23 – Nov 1

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 Sunflower's growing requirements.

Soil pH

Your soil pH (6.7–8.4) is more alkaline than Sunflower prefers (6.0–7.5). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Goshen County is excellent for Sunflower — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.9%). Annual compost additions will help Sunflower.

How to Plant Sunflower

1"
Planting Depth
18"
Between Plants
24"
Between Rows

Succession Planting Sunflower

2
successive plantings in your 139-day season

Sow every 8 weeks. Last sowing by Jun 21 to harvest before frost.

Sunflower Water Budget

Plant needs
0.5″/week
Rainfall provides
0.5″/week
You supply
0.0″/week
Watering frequency Only during dry spells
Season total 38 gal / 100 sq ft
Drought risk

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 1.2" 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.

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 needs ~1,105 GDD — county provides 1,807 GDD Excellent fit

Sunflower Planting Timeline — Yoder, WY

Sunflower Planting Calendar

Activity When Date Range
Start Indoors April 22 Apr 22 – May 6
Transplant Outdoors May 20 May 20 – Jun 3
Direct Sow May 20 May 20 – Jun 10
Bloom August 12 Aug 12 – Oct 21

Plant 1" deep · 18" apart · Rows 24" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July
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

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

139 days in Goshen County

Growing Tips for Sunflower in Yoder

Direct sow Sunflower outdoors after May 13 in Goshen 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.

Goshen County receives only 16" of rain annually. Sunflower needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Direct-sow 1 inch deep after last frost; germination takes 7-14 days at 65-75°F soil. Sunflowers dislike root disturbance so direct sowing is strongly preferred over transplanting. Plant in succession every 2 weeks for extended bloom. Stake tall varieties. Avoid overwatering — they tolerate drought once established. Birds will self-deadhead seed heads; leave them up through fall for wildlife.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes
  • Pole_beans

Check more plant combinations with our Companion Planting Checker →

🌱

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.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Goshen County, WY. Local conditions may vary. Last updated: June 2026.