Blog

When to Plant Watermelon in Huerfano County, CO

Huerfano County, Colorado Zone 5b April

April in the garden — Huerfano County, Colorado

We've pulled the most time-sensitive tasks for Huerfano County, Colorado this April and put them front and centre. Tackle them in order.

Avg. last frost May 12
Avg. first frost September 30
Soil temp (4") 23°F
Watering High
Pest pressure Low
Daylight 13 hrs
May prep starts now
  • Transplants going out: watermelon
  • Direct-sowing: watermelon

Instant PDF download. No spam, unsubscribe any time.

Watermelon is a sprawling vine crop that produces sweet, juicy fruits in hot weather. Varieties range from personal-sized icebox types to 50-pound giants.

Huerfano County, Colorado is in USDA Zone 5b. The average last spring frost is May 12 and the first fall frost is September 30, giving you a growing season of approximately 141 days.

At an elevation of 7,235 feet, Huerfano County receives approximately 15.2 inches of rainfall annually with predominantly loam soil. Summer highs average 83°F, so choose short-season varieties of Watermelon to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Watermelon successfully. Mulch heavily to conserve soil moisture.

Huerfano County, CO (Zone 5b) Short season
141 days
Last Spring Frost May 12
141 growing days
First Fall Frost September 30

Huerfano County Soil Profile

Soil Type

Loam

Soil pH

6.3-7.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (2 days to spare)
Start indoors: Apr 3 Transplant: May 22 🍅 Harvest: Jul 31 – Sep 18
Recommended (50%) ✓ Fits season (8 days to spare)
Start indoors: Apr 7 Transplant: May 26 🍅 Harvest: Aug 4 – Sep 22
Safe Start (90%) ✗ May not fit
Start indoors: May 10 Transplant: Jun 28 🍅 Harvest: Sep 6 – Oct 25

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 Huerfano County

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

Soil pH

Your soil pH (6.3–7.7) overlaps with Watermelon's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Watermelon.

Organic Matter

Organic matter is moderate (2.8%). Annual compost additions will help Watermelon.

How to Plant Watermelon

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Succession Planting Watermelon

2
successive plantings in your 141-day season

Sow every 8 weeks. Last sowing by Jun 22 to harvest before frost.

Plant Water Budget

Plant needs
1.5″/week
Rainfall provides
0.5″/week
You supply
1.8″/week
Watering frequency 2-3 times/week
Season total 2,255 gal / 100 sq ft
Drought risk

Water stress score is 8/10 — consider drought-tolerant varieties and mulching

Monthly Watering Guide for Watermelon

Watermelon needs approximately 1.5 inches of water per week (6.5" per month). Here's how your county's rainfall compares month by month.

Month Watermelon Needs Rainfall You Supplement Action
Jan 1" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.5" 0" ❄️ Dormant
May 6.5" 1.6" 4.9" 🚿 Regular watering
Jun 6.5" 1.1" 5.4" 🚿 Regular watering
Jul 6.5" 1.2" 5.3" 🚿 Regular watering
Aug 6.5" 1.8" 4.7" 🚿 Regular watering
Sep 6.5" 1.1" 5.4" 🚿 Regular watering
Oct 1.5" 0" ❄️ Dormant
Nov 1" 0" ❄️ Dormant
Dec 1" 0" ❄️ Dormant

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

Watermelon 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.

Watermelon needs ~1,041 GDD — county provides 1,727 GDD Excellent fit

Watermelon Planting Timeline — Huerfano County, CO

Watermelon Planting Calendar

Activity When Date Range
Start Indoors April 7 Apr 7 – Apr 21
Transplant Outdoors May 26 May 26 – Jun 9
Direct Sow May 19 May 19 – Jun 9
Harvest August 4 Aug 4 – Sep 22

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1.5"/week · 2-3 times/week

📅 Days to Maturity

70–100 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 5b

📆 Growing Season

141 days in Huerfano County

Growing Tips for Watermelon in Huerfano County

Direct sow Watermelon outdoors after May 12 in Huerfano County when soil has warmed and frost danger has passed.

Common pests for Watermelon in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

Huerfano County receives only 15" of rain annually. Watermelon needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 3-4 weeks early or direct sow after soil is warm. Plant on mounds with plenty of space. Check ripeness by looking for a yellow ground spot and dull thump when tapped.

Recommended Watermelon Varieties for Huerfano County

Compact, early melons for shorter seasons

Sugar Baby (75d) Blacktail Mountain (70d) Golden Midget (70d)

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Watermelon in Huerfano County, CO?

Huerfano County is in Zone 5b with an average last frost of May 12. Plan your Watermelon planting based on this frost date — see the calendar above for exact timing.

What planting zone is Huerfano County, CO?

Huerfano County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 12 and first fall frost is September 30.

🌱

Your Huerfano County Garden Planner — Free

A 24-page printable planner built for Huerfano 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.

Instant PDF download. No spam, unsubscribe any time.

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

Sources & credits

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