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When to Plant Onion in Scotts Bluff County, NE

Onions are a fundamental kitchen staple available in yellow, white, and red varieties. Choose long-day, short-day, or intermediate types based on your latitude.

Scotts Bluff County, Nebraska is in USDA Zone 4b. The average last spring frost is May 13 and the first fall frost is September 25, giving you a growing season of approximately 135 days.

At an elevation of 1,080 feet, Scotts Bluff County receives approximately 32.2 inches of rainfall annually with predominantly loam soil. Summer highs average 83ยฐF, so choose short-season varieties of Onion to ensure they mature before fall.

Scotts Bluff County, NE (Zone 4b) Short season
135 days
Last Spring Frost May 13
135 growing days
First Fall Frost September 25

Scotts Bluff County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 27 Transplant: May 8 🍅 Harvest: Aug 7 – Sep 25
Recommended (50%) ✗ May not fit
Start indoors: Apr 1 Transplant: May 13 🍅 Harvest: Aug 12 – Sep 30
Safe Start (90%) ✗ May not fit
Start indoors: Apr 27 Transplant: Jun 8 🍅 Harvest: Sep 7 – Oct 26

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 Scotts Bluff County

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

Soil pH

Your soil pH (6.3โ€“7.5) overlaps with Onion's range (6.0โ€“7.0), though not a perfect match.

Soil Texture

The loam soil in Scotts Bluff County is excellent for Onion โ€” good drainage, moisture retention, and nutrient holding capacity.

Drainage

Drainage is adequate for Onion.

Organic Matter

Organic matter is moderate (3.6%). Annual compost additions will help Onion.

How to Plant Onion

1"
Planting Depth
6"
Between Plants
12"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.0″/week
You supply
0.4″/week
Watering frequency 1-2 times/week
Season total 430 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Monthly Watering Guide for Onion

Onion needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Onion Needs Rainfall You Supplement Action
Jan โ€” 2.1" 0" โ„๏ธ Dormant
Feb โ€” 1.9" 0" โ„๏ธ Dormant
Mar โ€” 2.6" 0" โ„๏ธ Dormant
Apr โ€” 3" 0" โ„๏ธ Dormant
May 4.3" 4.1" 0.2" ๐Ÿ’ง Light watering
Jun 4.3" 2.2" 2.1" ๐Ÿ’ง Light watering
Jul 4.3" 3.3" 1" ๐Ÿ’ง Light watering
Aug 4.3" 3.9" 0.4" ๐Ÿ’ง Light watering
Sep 4.3" 2.6" 1.7" ๐Ÿ’ง Light watering
Oct โ€” 2.9" 0" โ„๏ธ Dormant
Nov โ€” 2" 0" โ„๏ธ Dormant
Dec โ€” 1.7" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Mayโ€“Sep in Scotts Bluff County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Onion 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" โ€” every day above 50ยฐF 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.

Onion needs ~1,286 GDD — county provides 1,653 GDD Good fit

Onion Planting Timeline โ€” Scotts Bluff County, NE

Onion Planting Calendar

Activity When Date Range
Start Indoors April 1 Apr 1 โ€“ Apr 15
Transplant Outdoors May 13 May 13 โ€“ May 27
Direct Sow May 6 May 6 โ€“ May 27
Harvest August 12 Aug 12 โ€“ Sep 30
Fall Sowing July 3 Jul 3 โ€“ Jul 17

Plant 1" deep ยท 6" apart ยท Rows 12" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Transplant Outdoors Direct Sow
June โ€”
July Fall Sowing
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

1"/week ยท 1-2 times/week

๐Ÿ“… Days to Maturity

90โ€“120 days

๐Ÿงช Soil pH

Needs 6โ€“7 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 4b

๐Ÿ“† Growing Season

135 days in Scotts Bluff County

Growing Tips for Onion in Scotts Bluff County

Direct sow Onion outdoors after May 13 in Scotts Bluff County when soil has warmed and frost danger has passed.

Common pests for Onion in this region include onion maggots and thrips. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors 8-10 weeks before transplanting. Match day-length type to your latitude. Stop watering when tops begin to fall over and cure bulbs for 2-3 weeks before storage.

Companion Planting

Good Companions

Avoid Planting Near

  • Peas
  • Green Beans
  • Asparagus

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Onion in Scotts Bluff County, NE?

Scotts Bluff County is in Zone 4b with an average last frost of May 13. Plan your Onion planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Scotts Bluff County, NE?

Scotts Bluff County, Nebraska is in USDA Hardiness Zone 4b. The average last spring frost is May 13 and first fall frost is September 25.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Scotts Bluff County gardeners in Zone 4b organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

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