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When to Plant Onion in Elko County, NV

Elko County, Nevada Zone 5b May

May in Elko County, Nevada — your action list

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

Avg. last frost June 5
Avg. first frost September 15
Soil temp (4") 42°F
Watering Critical
Pest pressure Low
Daylight 14.3 hrs
  1. Scatter onion into prepared beds

    Rake a smooth bed, make a shallow furrow, drop seeds at the spacing on the packet, water gently, walk away.

Coming up in June — start thinking about
  • Transplants going out: 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.

Elko County, Nevada is in USDA Zone 5b. The average last spring frost is June 5 and the first fall frost is September 15, giving you a growing season of approximately 102 days.

At an elevation of 5,859 feet, Elko County receives approximately 15.1 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 92°F, providing good warmth for Onion during the growing season. Sandy soil warms quickly in spring — great for early planting — but Onion will need more frequent watering and organic matter to retain nutrients. With low rainfall, drip irrigation is essential for growing Onion successfully. Mulch heavily to conserve soil moisture.

Elko County, NV (Zone 5b) Short season
102 days
Last Spring Frost June 5
102 growing days
First Fall Frost September 15
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Elko County Soil Profile

Soil Type

Sandy Loam

Soil pH

7.2-8.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 21 Transplant: May 26 🍅 Harvest: Aug 25 – Oct 13
Recommended (50%) ✗ May not fit
Start indoors: May 1 Transplant: Jun 5 🍅 Harvest: Sep 4 – Oct 23
Safe Start (90%) ✗ May not fit
Start indoors: May 14 Transplant: Jun 18 🍅 Harvest: Sep 17 – Nov 5

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 Elko County

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

Soil pH

Your soil pH (7.2–8.5) is more alkaline than Onion prefers (6.0–7.0). Add sulfur or peat moss to lower pH.

Soil Texture

Sandy soil in Elko County warms quickly in spring but drains fast. Onion will need more frequent watering and regular compost additions to retain nutrients.

Drainage

Drainage is adequate for Onion.

Organic Matter

Organic matter is low (0.8%). Add 2-3 inches of compost before planting Onion.

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
0.8″/week
Watering frequency 2-3 times/week
Season total 739 gal / 100 sq ft
Drought risk

Water stress score is 10/10 — 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 1" 0" ❄️ Dormant
Feb 0.8" 0" ❄️ Dormant
Mar 0.9" 0" ❄️ Dormant
Apr 0.5" 0" ❄️ Dormant
May 0.3" 0" ❄️ Dormant
Jun 4.3" 0.4" 3.9" 🚿 Regular watering
Jul 4.3" 2.7" 1.6" 💧 Light watering
Aug 4.3" 3.1" 1.2" 💧 Light watering
Sep 4.3" 2" 2.3" 🚿 Regular watering
Oct 1.5" 0" ❄️ Dormant
Nov 0.7" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Elko 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 ~1,995 GDD — county provides 1,938 GDD Tight fit

Onion Planting Timeline — Elko County, NV

Onion Planting Calendar

Activity When Date Range
Start Indoors May 1 May 1 – May 15
Transplant Outdoors June 5 Jun 5 – Jun 19
Direct Sow May 22 May 22 – Jun 12
Harvest September 4 Sep 4 – Oct 23
Fall Sowing July 7 Jul 7 – Jul 21

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

102 days in Elko County

Growing Tips for Onion in Elko County

Direct sow Onion outdoors after June 05 in Elko County when soil has warmed and frost danger has passed.

Sandy soil in Elko County dries quickly — mulch Onion with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Your 102.0-day growing season in Elko County is tight for Onion (90.0-120.0 days to maturity). Start indoors and choose early-maturing varieties.

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

Elko County receives only 15" 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 Elko County, NV?

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

What planting zone is Elko County, NV?

Elko County, Nevada is in USDA Hardiness Zone 5b. The average last spring frost is June 5 and first fall frost is September 15.

🌱

Your Elko County Garden Planner — Free

A 24-page printable planner built for Elko 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 Elko County, NV. 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.