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When to Plant Jicama in Adams County, WA

Adams County, Washington Zone 7a May

Your May planting checklist for Adams County, Washington

Here's what deserves your attention in Adams County, Washington this month. Everything below is tailored to Zone 7a and timed around your local frost dates.

Avg. last frost May 7
Avg. first frost October 3
Soil temp (4") 55°F
Watering Critical
Pest pressure Low
Daylight 14.9 hrs
  1. Transplant jicama outside

    Your last frost (May 7) has passed. These warm-season crops can handle outdoor soil now.

  2. Sow jicama where they'll grow

    Sow every 2 weeks for a continuous harvest. A single big planting means a single big glut.

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.

Adams County, Washington is in USDA Zone 7a. The average last spring frost is May 7 and the first fall frost is October 3, giving you a growing season of approximately 149 days.

At an elevation of 2,402 feet, Adams County receives approximately 17.1 inches of rainfall annually with predominantly silt loam soil. Summer highs average 91°F, providing good warmth for Jicama during the growing season. With low rainfall, drip irrigation is essential for growing Jicama successfully. Mulch heavily to conserve soil moisture.

Adams County, WA (Zone 7a) Short season
149 days
Last Spring Frost May 7
149 growing days
First Fall Frost October 3

Adams County Soil Profile

Soil Type

Silt Loam

Soil pH

5.7-6.4

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Mar 9 Transplant: May 11 🍅 Harvest: Sep 14 – Nov 23
Recommended (50%) ✗ May not fit
Start indoors: Mar 19 Transplant: May 21 🍅 Harvest: Sep 24 – Dec 3
Safe Start (90%) ✗ May not fit
Start indoors: Apr 3 Transplant: Jun 5 🍅 Harvest: Oct 9 – Dec 18

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 Adams County

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

Soil pH

Your soil pH (5.7–6.4) overlaps with Jicama's range (6.0–7.5), though not a perfect match.

Soil Texture

The silt loam soil in Adams 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
0.5″/week
You supply
0.6″/week
Watering frequency 1-2 times/week
Season total 824 gal / 100 sq ft
Drought risk

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

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 2.7" 0" ❄️ Dormant
Feb 1.7" 0" ❄️ Dormant
Mar 1.5" 0" ❄️ Dormant
Apr 1.4" 0" ❄️ Dormant
May 4.3" 0.8" 3.5" 🚿 Regular watering
Jun 4.3" 0.6" 3.7" 🚿 Regular watering
Jul 4.3" 0.3" 4" 🚿 Regular watering
Aug 4.3" 0.4" 3.9" 🚿 Regular watering
Sep 4.3" 0.6" 3.7" 🚿 Regular watering
Oct 4.3" 1.6" 2.7" 🚿 Regular watering
Nov 2.5" 0" ❄️ Dormant
Dec 3" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Adams 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 ~2,738 GDD — county provides 2,719 GDD Tight fit

Jicama Planting Timeline — Adams County, WA

Jicama Planting Calendar

Activity When Date Range
Start Indoors March 19 Mar 19 – Apr 2
Transplant Outdoors May 21 May 21 – Jun 4
Direct Sow May 14 May 14 – Jun 4
Harvest September 24 Sep 24 – Dec 3

Plant 0.5" deep · 6" apart · Rows 12" 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
September Harvest
October Harvest
November Harvest
December Harvest

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · 1-2 times/week

📅 Days to Maturity

120–180 days

🧪 Soil pH

Needs 6–7.5 · Your soil: acceptable

🗺️ USDA Zone

Zone 7a

📆 Growing Season

149 days in Adams County

Growing Tips for Jicama in Adams County

Direct sow Jicama outdoors after May 07 in Adams County when soil has warmed and frost danger has passed.

Your 149.0-day growing season in Adams 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.

Adams County receives only 17" 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 Adams County, WA?

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

What planting zone is Adams County, WA?

Adams County, Washington is in USDA Hardiness Zone 7a. The average last spring frost is May 7 and first fall frost is October 3.

🌱

Your Adams County Garden Planner — Free

A 24-page printable planner built for Adams County (Zone 7a). 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 Adams County, WA. 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.