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When to Plant Sweet Potatoes in Gilpin County, CO

Gilpin County, Colorado Zone 5b May

Top priorities for Gilpin County, Colorado gardeners in May

May rewards gardeners who work with the weather, not against it. Here's how to stay in step this month in Gilpin County, Colorado.

Avg. last frost May 14
Avg. first frost September 26
Soil temp (4") 34°F
Watering High
Pest pressure Low
Daylight 14.2 hrs
  1. Plant out sweet potatoes

    Your last frost (May 14) has passed. These warm-season crops can handle outdoor soil now.

  2. Direct-sow sweet potatoes

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

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Sweet potatoes are a warm-season root crop that produces nutritious, sweet tubers in orange, white, and purple varieties. They need a long, hot growing season.

Gilpin County, Colorado is in USDA Zone 5b. The average last spring frost is May 14 and the first fall frost is September 26, giving you a growing season of approximately 135 days.

At an elevation of 6,444 feet, Gilpin County receives approximately 18.6 inches of rainfall annually with predominantly loam soil. Summer highs average 81°F, so choose short-season varieties of Sweet Potatoes to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Sweet Potatoes successfully. Mulch heavily to conserve soil moisture.

Gilpin County, CO (Zone 5b) Short season
135 days
Last Spring Frost May 14
135 growing days
First Fall Frost September 26

Gilpin County Soil Profile

Soil Type

Loam

Soil pH

6.8-8

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 8 Transplant: May 17 🍅 Harvest: Aug 16 – Oct 4
Recommended (50%) ✗ May not fit
Start indoors: Mar 19 Transplant: May 28 🍅 Harvest: Aug 27 – Oct 15
Safe Start (90%) ✗ May not fit
Start indoors: Apr 15 Transplant: Jun 24 🍅 Harvest: Sep 23 – Nov 11

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 Gilpin County

How your county's soil matches Sweet Potatoes's growing requirements.

Soil pH

Your soil pH (6.8–8.0) is more alkaline than Sweet Potatoes prefers (5.5–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Gilpin County is excellent for Sweet Potatoes — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.3%). Annual compost additions will help Sweet Potatoes.

How to Plant Sweet Potatoes

1"
Planting Depth
15"
Between Plants
24"
Between Rows

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 607 gal / 100 sq ft
Drought risk

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

Monthly Watering Guide for Sweet Potatoes

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

Month Sweet Potatoes Needs Rainfall You Supplement Action
Jan 1.4" 0" ❄️ Dormant
Feb 1" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 2.1" 0" ❄️ Dormant
May 4.3" 1.8" 2.5" 🚿 Regular watering
Jun 4.3" 1.4" 2.9" 🚿 Regular watering
Jul 4.3" 1.7" 2.6" 🚿 Regular watering
Aug 4.3" 2.1" 2.2" 🚿 Regular watering
Sep 4.3" 1.3" 3" 🚿 Regular watering
Oct 1.7" 0" ❄️ Dormant
Nov 1.4" 0" ❄️ Dormant
Dec 1.2" 0" ❄️ Dormant

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

Sweet Potatoes 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.

Sweet Potatoes needs ~1,129 GDD — county provides 1,451 GDD Good fit

Sweet Potatoes Planting Timeline — Gilpin County, CO

Sweet Potatoes Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors May 28 May 28 – Jun 11
Direct Sow May 21 May 21 – Jun 11
Harvest August 27 Aug 27 – Oct 15

Plant 1" deep · 15" apart · Rows 24" apart

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 5b

📆 Growing Season

135 days in Gilpin County

Growing Tips for Sweet Potatoes in Gilpin County

Direct sow Sweet Potatoes outdoors after May 14 in Gilpin County when soil has warmed and frost danger has passed.

Gilpin County receives only 19" of rain annually. Sweet Potatoes needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Plant slips (rooted sprouts) after soil is thoroughly warm. Build raised mounds for better root development. Cure harvested roots at 80-85F for 10 days to develop sweetness.

Companion Planting

Good Companions

Avoid Planting Near

  • Squash Summer

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Sweet Potatoes in Gilpin County, CO?

Gilpin County is in Zone 5b with an average last frost of May 14. Plan your Sweet Potatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gilpin County, CO?

Gilpin County, Colorado is in USDA Hardiness Zone 5b. The average last spring frost is May 14 and first fall frost is September 26.

🌱

Your Gilpin County Garden Planner — Free

A 24-page printable planner built for Gilpin 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 Gilpin County, CO. 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.