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When to Plant Onion in Cedar County, NE

Cedar County, Nebraska Zone 5a May

May to-do list for Cedar County, Nebraska

May is a pivotal month for Cedar County, Nebraska gardens. Focus on these tasks first and you'll set up the rest of the season for success.

Avg. last frost April 30
Avg. first frost October 7
Soil temp (4") 53°F
Watering High
Pest pressure Low
Daylight 14.4 hrs
June will be here before you know it — start on
  • Starting indoors: onion

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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.

Cedar County, Nebraska is in USDA Zone 5a. The average last spring frost is April 30 and the first fall frost is October 7, giving you a growing season of approximately 160 days.

At an elevation of 899 feet, Cedar County receives approximately 21.1 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Onion to ensure they mature before fall.

Cedar County, NE (Zone 5a) Moderate season
160 days
Last Spring Frost April 30
160 growing days
First Fall Frost October 7
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Cedar County Soil Profile

Soil Type

Loam

Soil pH

6.5-7.3

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (23 days to spare)
Start indoors: Mar 19 Transplant: Apr 23 🍅 Harvest: Jul 23 – Sep 10
Recommended (50%) ✓ Fits season (20 days to spare)
Start indoors: Mar 26 Transplant: Apr 30 🍅 Harvest: Jul 30 – Sep 17
Safe Start (90%) ✓ Fits season (17 days to spare)
Start indoors: Apr 10 Transplant: May 15 🍅 Harvest: Aug 14 – Oct 2

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 Cedar County

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

Soil pH

Your soil pH (6.5–7.3) overlaps with Onion's range (6.0–7.0), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (4.3%) — Onion will thrive.

How to Plant Onion

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

Fall planting: Sow 10 weeks before your first frost date for a fall harvest.

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.6″/week
You supply
0.5″/week
Watering frequency 1-2 times/week
Season total 762 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — 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 0.5" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 4.3" 2.4" 1.9" 💧 Light watering
May 4.3" 2.7" 1.6" 💧 Light watering
Jun 4.3" 3.3" 1" 💧 Light watering
Jul 4.3" 2.9" 1.4" 💧 Light watering
Aug 4.3" 2.4" 1.9" 💧 Light watering
Sep 4.3" 1.8" 2.5" 🚿 Regular watering
Oct 4.3" 1.4" 2.9" 🚿 Regular watering
Nov 0.7" 0" ❄️ Dormant
Dec 0.6" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Cedar County). Supplement amounts are based on average rainfall — 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" — 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.

Onion needs ~1,208 GDD — county provides 1,840 GDD Excellent fit

Onion Planting Timeline — Cedar County, NE

Onion Planting Calendar

Activity When Date Range
Start Indoors March 26 Mar 26 – Apr 9
Transplant Outdoors April 30 Apr 30 – May 14
Direct Sow April 16 Apr 16 – May 7
Harvest July 30 Jul 30 – Sep 17
Fall Sowing July 29 Jul 29 – Aug 12

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: acceptable

🗺️ USDA Zone

Zone 5a

📆 Growing Season

160 days in Cedar County

Growing Tips for Onion in Cedar County

Direct sow Onion outdoors after April 30 in Cedar 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.

Cedar County receives only 21" of rain annually. Onion needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

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 Cedar County, NE?

Cedar County is in Zone 5a with an average last frost of April 30. Plan your Onion planting based on this frost date — see the calendar above for exact timing.

What planting zone is Cedar County, NE?

Cedar County, Nebraska is in USDA Hardiness Zone 5a. The average last spring frost is April 30 and first fall frost is October 7.

🌱

Your Cedar County Garden Planner — Free

A 24-page printable planner built for Cedar 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.

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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 Cedar County, NE. Local conditions may vary. Last updated: May 2026.

Sources & credits

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