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When to Plant Sweet Potatoes in Deschutes County, OR

Deschutes County, Oregon Zone 6b May

Top priorities for Deschutes County, Oregon gardeners in May

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

Avg. last frost June 15
Avg. first frost September 13
Soil temp (4") 62°F
Watering Moderate
Pest pressure Low
Daylight 14.5 hrs
June will be here before you know it — start on
  • Transplants going out: sweet potatoes
  • Direct-sowing: sweet potatoes

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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.

Deschutes County, Oregon is in USDA Zone 6b. The average last spring frost is June 15 and the first fall frost is September 13, giving you a growing season of approximately 90 days.

At an elevation of 221 feet, Deschutes County receives approximately 54.7 inches of rainfall annually with predominantly silt loam soil. Summer highs average 81°F, so choose short-season varieties of Sweet Potatoes to ensure they mature before fall. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sweet Potatoes root diseases.

Deschutes County, OR (Zone 6b) Very short season
90 days
Last Spring Frost June 15
90 growing days
First Fall Frost September 13
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Deschutes County Soil Profile

Soil Type

Silt Loam

Soil pH

5.4-6.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 8 Transplant: Jun 17 🍅 Harvest: Sep 16 – Nov 4
Recommended (50%) ✗ May not fit
Start indoors: Apr 20 Transplant: Jun 29 🍅 Harvest: Sep 28 – Nov 16
Safe Start (90%) ✗ May not fit
Start indoors: May 1 Transplant: Jul 10 🍅 Harvest: Oct 9 – Nov 27

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 Deschutes County

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

Soil pH

Your soil pH (5.4–6.2) overlaps with Sweet Potatoes's range (5.5–6.5), though not a perfect match.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.0%) — Sweet Potatoes will thrive.

How to Plant Sweet Potatoes

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
2.6″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

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 7.6" 0" ❄️ Dormant
Feb 6.2" 0" ❄️ Dormant
Mar 4.9" 0" ❄️ Dormant
Apr 3.8" 0" ❄️ Dormant
May 3" 0" ❄️ Dormant
Jun 4.3" 2.5" 1.8" 💧 Light watering
Jul 4.3" 1" 3.3" 🚿 Regular watering
Aug 4.3" 1" 3.3" 🚿 Regular watering
Sep 4.3" 2.2" 2.1" 💧 Light watering
Oct 4.9" 0" ❄️ Dormant
Nov 7.8" 0" ❄️ Dormant
Dec 9.9" 0" ❄️ Dormant

Water needs are for active growing months only (Jun–Sep in Deschutes 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 967 GDD May not mature

Sweet Potatoes Planting Timeline — Deschutes County, OR

Sweet Potatoes Planting Calendar

Activity When Date Range
Start Indoors April 20 Apr 20 – May 4
Transplant Outdoors June 29 Jun 29 – Jul 13
Direct Sow June 22 Jun 22 – Jul 13
Harvest September 28 Sep 28 – Nov 16

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 6b

📆 Growing Season

90 days in Deschutes County

Growing Tips for Sweet Potatoes in Deschutes County

Direct sow Sweet Potatoes outdoors after June 15 in Deschutes County when soil has warmed and frost danger has passed.

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

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 Deschutes County, OR?

Deschutes County is in Zone 6b with an average last frost of June 15. Plan your Sweet Potatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is Deschutes County, OR?

Deschutes County, Oregon is in USDA Hardiness Zone 6b. The average last spring frost is June 15 and first fall frost is September 13.

🌱

Your Deschutes County Garden Planner — Free

A 24-page printable planner built for Deschutes County (Zone 6b). 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 Deschutes County, OR. 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.