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When to Plant Jicama in Gilliam County, OR

Gilliam County, Oregon Zone 7b May

May to-do list for Gilliam County, Oregon

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

Avg. last frost April 25
Avg. first frost October 15
Soil temp (4") 63°F
Watering High
Pest pressure Low
Daylight 14.7 hrs
  1. Move jicama into the garden

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Direct-sow jicama

    Succession planting is the secret here. Put in a row now, another in 2 weeks, a third in 4.

Coming up in June — start thinking about
  • Starting indoors: jicama

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Jicama is a tropical legume grown for its crisp, sweet, starchy root. It requires a very long, warm growing season but produces a refreshing, water chestnut-like tuber.

Gilliam County, Oregon is in USDA Zone 7b. The average last spring frost is April 25 and the first fall frost is October 15, giving you a growing season of approximately 173 days.

At an elevation of 965 feet, Gilliam County receives approximately 22.4 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Jicama during the growing season.

Gilliam County, OR (Zone 7b) Moderate season
173 days
Last Spring Frost April 25
173 growing days
First Fall Frost October 15
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Gilliam County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.7

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Feb 25 Transplant: Apr 29 🍅 Harvest: Sep 2 – Nov 11
Recommended (50%) ✗ May not fit
Start indoors: Mar 7 Transplant: May 9 🍅 Harvest: Sep 12 – Nov 21
Safe Start (90%) ✗ May not fit
Start indoors: Mar 25 Transplant: May 27 🍅 Harvest: Sep 30 – Dec 9

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 Gilliam County

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

Soil pH

Your soil pH (5.3–6.7) overlaps with Jicama's range (6.0–7.5), though not a perfect match.

Soil Texture

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

Drainage

Drainage is adequate for Jicama.

Organic Matter

Organic matter is excellent (4.5%) — Jicama will thrive.

How to Plant Jicama

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.5″/week
You supply
0.8″/week
Watering frequency 2-3 times/week
Season total 1,164 gal / 100 sq ft

Monthly Watering Guide for Jicama

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

Month Jicama Needs Rainfall You Supplement Action
Jan 2.8" 0" ❄️ Dormant
Feb 2.8" 0" ❄️ Dormant
Mar 2.4" 0" ❄️ Dormant
Apr 4.3" 1.4" 2.9" 🚿 Regular watering
May 4.3" 1.4" 2.9" 🚿 Regular watering
Jun 4.3" 0.8" 3.5" 🚿 Regular watering
Jul 4.3" 0.3" 4" 🚿 Regular watering
Aug 4.3" 0.5" 3.8" 🚿 Regular watering
Sep 4.3" 0.9" 3.4" 🚿 Regular watering
Oct 4.3" 1.7" 2.6" 🚿 Regular watering
Nov 3.7" 0" ❄️ Dormant
Dec 3.8" 0" ❄️ Dormant

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

Jicama 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.

Jicama needs ~2,062 GDD — county provides 2,378 GDD Good fit

Jicama Planting Timeline — Gilliam County, OR

Jicama Planting Calendar

Activity When Date Range
Start Indoors March 7 Mar 7 – Mar 21
Transplant Outdoors May 9 May 9 – May 23
Direct Sow May 2 May 2 – May 23
Harvest September 12 Sep 12 – Nov 21

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 2-3 times/week

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 7b

📆 Growing Season

173 days in Gilliam County

Growing Tips for Jicama in Gilliam County

Direct sow Jicama outdoors after April 25 in Gilliam County when soil has warmed and frost danger has passed.

Your 173.0-day growing season in Gilliam County is tight for Jicama (120.0-180.0 days to maturity). Start indoors and choose early-maturing varieties.

Common pests for Jicama in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

Gilliam County receives only 22" of rain annually. Jicama needs consistent moisture — install drip irrigation or water deeply 2-3 times per week.

General growing tips

Start seeds indoors 8-10 weeks before last frost. Pinch off flowers to direct energy to root development. Harvest before first frost when roots are 3-6 inches across.

Companion Planting

Good Companions

Avoid Planting Near

  • Fennel

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Jicama in Gilliam County, OR?

Gilliam County is in Zone 7b with an average last frost of April 25. Plan your Jicama planting based on this frost date — see the calendar above for exact timing.

What planting zone is Gilliam County, OR?

Gilliam County, Oregon is in USDA Hardiness Zone 7b. The average last spring frost is April 25 and first fall frost is October 15.

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Your Gilliam County Garden Planner — Free

A 24-page printable planner built for Gilliam County (Zone 7b). 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 Gilliam 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.