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When to Plant Sunflower in Keith County, NE

Keith County, Nebraska Zone 5b July

July in Keith County, Nebraska — your action list

Your garden in Keith County, Nebraska is working on a schedule, even when you're not. Here's where you should be this July.

Avg. last frost May 3
Avg. first frost October 7
Soil temp (4") 72°F
Watering High
Pest pressure High
Daylight 14.7 hrs
Before August arrives, get these ready
  • First harvests: sunflower

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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.

Keith County, Nebraska is in USDA Zone 5b. The average last spring frost is May 3 and the first fall frost is October 7, giving you a growing season of approximately 157 days.

At an elevation of 1,091 feet, Keith County receives approximately 22 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Sunflower to ensure they mature before fall.

Annual Blooms in Summer Pollinator-friendly Good for cutting
Keith County, NE (Zone 5b) Moderate season
157 days
Last Spring Frost May 3
157 growing days
First Fall Frost October 7

Keith County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.5

Drainage

Well Drained

Sunflower Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 9 Transplant: May 7 🌸 Bloom: Jul 30 – Oct 15
Recommended (50%) ✗ May not fit
Start indoors: Apr 12 Transplant: May 10 🌸 Bloom: Aug 2 – Oct 18
Safe Start (90%) ✗ May not fit
Start indoors: Apr 22 Transplant: May 20 🌸 Bloom: Aug 12 – Oct 28

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 Keith County

How your county's soil matches Sunflower's growing requirements.

Soil pH

Your soil pH (6.7–7.5) is within Sunflower's preferred range (6.0–7.5).

Soil Texture

The loam soil in Keith 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

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

Succession Planting Sunflower

2
successive plantings in your 157-day season

Sow every 8 weeks. Last sowing by Jun 29 to harvest before frost.

Sunflower Water Budget

Plant needs
0.5″/week
Rainfall provides
0.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft
Drought risk

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 1.7" 0" ❄️ Dormant
Feb 1.4" 0" ❄️ Dormant
Mar 2.1" 0" ❄️ Dormant
Apr 2.2" 0" ❄️ Dormant
May 2.2" 2.2" 0" ✅ Rainfall sufficient
Jun 2.2" 1.7" 0.5" 💧 Light watering
Jul 2.2" 1.9" 0.3" 💧 Light watering
Aug 2.2" 2.2" 0" ✅ Rainfall sufficient
Sep 2.2" 2.1" 0.1" 💧 Light watering
Oct 2.2" 1.7" 0.5" 💧 Light watering
Nov 1.5" 0" ❄️ Dormant
Dec 1.3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Keith 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 ~1,041 GDD — county provides 1,923 GDD Excellent fit

Sunflower Planting Timeline — Keith County, NE

Sunflower Planting Calendar

Activity When Date Range
Start Indoors April 12 Apr 12 – Apr 26
Transplant Outdoors May 10 May 10 – May 24
Direct Sow May 10 May 10 – May 31
Bloom August 2 Aug 2 – Oct 18

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

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Transplant Outdoors Direct Sow
June
July
August Bloom
September Bloom
October Bloom
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: ideal

🗺️ USDA Zone

Zone 5b

📆 Growing Season

157 days in Keith County

Growing Tips for Sunflower in Keith County

Direct sow Sunflower outdoors after May 03 in Keith 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.

Keith County receives only 22" 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 →

Frequently Asked Questions

When should I plant Sunflower in Keith County, NE?

Keith County is in Zone 5b with an average last frost of May 3. Plan your Sunflower planting based on this frost date — see the calendar above for exact timing.

What planting zone is Keith County, NE?

Keith County, Nebraska is in USDA Hardiness Zone 5b. The average last spring frost is May 3 and first fall frost is October 7.

🌱

Your Keith County Garden Planner — Free

A 22-page printable planner built for Keith 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.

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

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.