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When to Plant Carrots in Niobrara County, WY

Niobrara County, Wyoming Zone 5a May

This month in Niobrara County, Wyoming

We've pulled the most time-sensitive tasks for Niobrara County, Wyoming this May and put them front and centre. Tackle them in order.

Avg. last frost May 15
Avg. first frost September 21
Soil temp (4") 40°F
Watering High
Pest pressure Low
Daylight 14.5 hrs
  1. Sow carrots where they'll grow

    These tolerate cool soil, so you're not gambling by sowing now.

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Carrots are a popular root vegetable available in orange, purple, white, and yellow varieties. They are rich in beta-carotene and have a sweet, earthy flavor.

Niobrara County, Wyoming is in USDA Zone 5a. The average last spring frost is May 15 and the first fall frost is September 21, giving you a growing season of approximately 129 days.

At an elevation of 5,262 feet, Niobrara County receives approximately 19.5 inches of rainfall annually with predominantly loam soil. Summer highs average 82°F, so choose short-season varieties of Carrots to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Carrots successfully. Mulch heavily to conserve soil moisture.

Niobrara County, WY (Zone 5a) Short season
129 days
Last Spring Frost May 15
129 growing days
First Fall Frost September 21
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Niobrara County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (28 days to spare)
Transplant: May 13 🍅 Harvest: Jul 15 – Aug 19
Recommended (50%) ✓ Fits season (31 days to spare)
Transplant: May 15 🍅 Harvest: Jul 17 – Aug 21
Safe Start (90%) ✓ Fits season (26 days to spare)
Transplant: Jun 4 🍅 Harvest: Aug 6 – Sep 10

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 Niobrara County

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

Soil pH

Your soil pH (6.2–7.9) is more alkaline than Carrots prefers (6.0–6.8). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is moderate (2.2%). Annual compost additions will help Carrots.

How to Plant Carrots

0.5"
Planting Depth
6"
Between Plants
12"
Between Rows

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

Succession Planting Carrots

2
successive plantings in your 129-day season

Sow every 6.9 weeks. Last sowing by Jul 03 to harvest before frost.

For a dedicated fall crop, sow by Jul 13.

Plant Water Budget

Plant needs
0.8″/week
Rainfall provides
0.6″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 227 gal / 100 sq ft
Drought risk

Water stress score is 6/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Carrots

Carrots needs approximately 0.8 inches of water per week (3.5" per month). Here's how your county's rainfall compares month by month.

Month Carrots Needs Rainfall You Supplement Action
Jan 1.2" 0" ❄️ Dormant
Feb 1.2" 0" ❄️ Dormant
Mar 1.8" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 3.5" 2.2" 1.3" 💧 Light watering
Jun 3.5" 1.3" 2.2" 🚿 Regular watering
Jul 3.5" 1.8" 1.7" 💧 Light watering
Aug 3.5" 2.1" 1.4" 💧 Light watering
Sep 3.5" 1.5" 2" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.5" 0" ❄️ Dormant
Dec 1.1" 0" ❄️ Dormant

Water needs are for active growing months only (May–Sep in Niobrara County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Carrots 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.

Carrots needs ~805 GDD — county provides 1,483 GDD Excellent fit

Carrots Planting Timeline — Niobrara County, WY

Carrots Planting Calendar

Activity When Date Range
Direct Sow May 1 May 1 – May 22
Harvest July 3 Jul 3 – Aug 7
Fall Sowing July 13 Jul 13 – Jul 27

Plant 0.5" deep · 6" apart · Rows 12" apart

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

0.8"/week · Only during dry spells

📅 Days to Maturity

60–80 days

🧪 Soil pH

Needs 6–6.8 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5a

📆 Growing Season

129 days in Niobrara County

Growing Tips for Carrots in Niobrara County

Direct sow Carrots outdoors after May 15 in Niobrara County when soil has warmed and frost danger has passed.

Common pests for Carrots in this region include carrot rust fly and parsleyworm. Use row covers early in the season and inspect plants weekly.

General growing tips

Sow seeds directly in loose, stone-free soil for straight roots. Keep soil moist until germination which can take 2-3 weeks. Thin seedlings to 2 inches apart.

Recommended Carrots Varieties for Niobrara County

Fast-maturing varieties for your season

Adelaide (50d) Mokum (54d) Nelson (56d)

Companion Planting

Good Companions

Avoid Planting Near

  • Dill
  • Parsnip

Check more plant combinations with our Companion Planting Checker →

🌾 Save Your Own Carrots Seeds
Life Cycle Biennial
Pollination Cross-Pollinated (insects)
How to Collect Replant roots for 2nd year flowers. Harvest umbels when brown.
Storage Store airtight; viable 3 years at 35°F, under 50% humidity.

Isolate 1/2 mile from Queen Anne's Lace (wild carrot). Biennial — requires two seasons.

Frequently Asked Questions

When should I plant Carrots in Niobrara County, WY?

Niobrara County is in Zone 5a with an average last frost of May 15. Plan your Carrots planting based on this frost date — see the calendar above for exact timing.

What planting zone is Niobrara County, WY?

Niobrara County, Wyoming is in USDA Hardiness Zone 5a. The average last spring frost is May 15 and first fall frost is September 21.

🌱

Your Niobrara County Garden Planner — Free

A 24-page printable planner built for Niobrara 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 Niobrara County, WY. 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.