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When to Plant Jicama in Tillamook County, OR

Tillamook County, Oregon Zone 9a May

Top priorities for Tillamook County, Oregon gardeners in May

Your garden in Tillamook County, Oregon is working on a schedule, even when you're not. Here's where you should be this May.

Avg. last frost April 19
Avg. first frost October 29
Soil temp (4") 71°F
Watering High
Pest pressure High
Daylight 14.7 hrs
  1. Sow jicama in trays indoors

    Bottom-water once the first true leaves appear — it keeps stems dry and knocks back damping-off.

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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.

Tillamook County, Oregon is in USDA Zone 9a. The average last spring frost is April 19 and the first fall frost is October 29, giving you a growing season of approximately 193 days.

At an elevation of 332 feet, Tillamook County receives approximately 40.8 inches of rainfall annually with predominantly silt loam soil. Summer highs average 85°F, providing good warmth for Jicama during the growing season.

Tillamook County, OR (Zone 9a) Moderate season
193 days
Last Spring Frost April 19
193 growing days
First Fall Frost October 29

Tillamook County Soil Profile

Soil Type

Silt Loam

Soil pH

5.3-6.5

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 1 Transplant: Apr 19 🍅 Harvest: Aug 23 – Nov 1
Recommended (50%) ✗ May not fit
Start indoors: Mar 8 Transplant: Apr 26 🍅 Harvest: Aug 30 – Nov 8
Safe Start (90%) ✗ May not fit
Start indoors: Mar 27 Transplant: May 15 🍅 Harvest: Sep 18 – 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 Tillamook County

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

Soil pH

Your soil pH (5.3–6.5) is more acidic than Jicama prefers (6.0–7.5). Add garden lime to raise pH.

Soil Texture

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

Organic Matter

Organic matter is excellent (5.3%) — 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
0.9″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 193 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 5.4" 0" ❄️ Dormant
Feb 4.1" 0" ❄️ Dormant
Mar 4.1" 0" ❄️ Dormant
Apr 4.3" 3.4" 0.9" 💧 Light watering
May 4.3" 2.5" 1.8" 💧 Light watering
Jun 4.3" 1.8" 2.5" 🚿 Regular watering
Jul 4.3" 0.7" 3.6" 🚿 Regular watering
Aug 4.3" 0.8" 3.5" 🚿 Regular watering
Sep 4.3" 1.8" 2.5" 🚿 Regular watering
Oct 4.3" 3.7" 0.6" 💧 Light watering
Nov 6.4" 0" ❄️ Dormant
Dec 6.2" 0" ❄️ Dormant

Water needs are for active growing months only (Apr–Oct in Tillamook 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 2,653 GDD Good fit

Jicama Planting Timeline — Tillamook County, OR

Jicama Planting Calendar

Activity When Date Range
Start Indoors March 8 Mar 8 – Mar 22
Transplant Outdoors April 26 Apr 26 – May 10
Direct Sow April 19 Apr 19 – May 10
Harvest August 30 Aug 30 – Nov 8

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: too_acidic

🗺️ USDA Zone

Zone 9a

📆 Growing Season

193 days in Tillamook County

Growing Tips for Jicama in Tillamook County

Direct sow Jicama outdoors after April 19 in Tillamook County when soil has warmed and frost danger has passed.

Your 193.0-day growing season in Tillamook 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.

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 Tillamook County, OR?

Tillamook County is in Zone 9a with an average last frost of April 19. Plan your Jicama planting based on this frost date — see the calendar above for exact timing.

What planting zone is Tillamook County, OR?

Tillamook County, Oregon is in USDA Hardiness Zone 9a. The average last spring frost is April 19 and first fall frost is October 29.

🌱

Your Tillamook County Garden Planner — Free

A 24-page printable planner built for Tillamook County (Zone 9a). 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 Tillamook 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.