Blog

When to Plant Yam in Zapata County, TX

Zapata County, Texas Zone 9b May

Your May game plan for Zapata County, Texas

We've pulled the most time-sensitive tasks for Zapata County, Texas this May and put them front and centre. Tackle them in order.

Avg. last frost February 3
Avg. first frost December 14
Soil temp (4") 67°F
Watering Low
Pest pressure High
Daylight 13.3 hrs

Instant PDF download. No spam, unsubscribe any time.

True yams are tropical tubers distinct from sweet potatoes, producing large starchy roots that can weigh several pounds. They are a staple food in tropical regions worldwide.

Zapata County, Texas is in USDA Zone 9b. The average last spring frost is February 3 and the first fall frost is December 14, giving you a growing season of approximately 314 days.

At an elevation of 3,340 feet, Zapata County receives approximately 60.6 inches of rainfall annually with predominantly loam soil. Summer highs average 103°F, so Yam may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Yam root diseases.

Zapata County, TX (Zone 9b) Year-round
314 days
Last Spring Frost February 3
314 growing days
First Fall Frost December 14
Share this guide:

Zapata County Soil Profile

Soil Type

Loam

Soil pH

6.2-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (15 days to spare)
Start indoors: Dec 6 Transplant: Jan 24 🍅 Harvest: Jul 25 – Nov 21
Recommended (50%) ✓ Fits season (6 days to spare)
Start indoors: Dec 23 Transplant: Feb 10 🍅 Harvest: Aug 11 – Dec 8
Safe Start (90%) ✓ Fits season (357 days to spare)
Start indoors: Jan 16 Transplant: Mar 6 🍅 Harvest: Sep 4 – Jan 1

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 Zapata County

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

Soil pH

Your soil pH (6.2–7.6) is more alkaline than Yam prefers (5.5–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

The loam soil in Zapata County is excellent for Yam — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Yam.

How to Plant Yam

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

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
0.8″/week
You supply
0.2″/week
Watering frequency Only during dry spells
Season total 538 gal / 100 sq ft

Monthly Watering Guide for Yam

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

Month Yam Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 4.3" 2.3" 2" 💧 Light watering
Mar 4.3" 4.1" 0.2" 💧 Light watering
Apr 4.3" 6.3" 0" ✅ Rainfall sufficient
May 4.3" 7.6" 0" ✅ Rainfall sufficient
Jun 4.3" 10.1" 0" ✅ Rainfall sufficient
Jul 4.3" 8.6" 0" ✅ Rainfall sufficient
Aug 4.3" 7.4" 0" ✅ Rainfall sufficient
Sep 4.3" 6.1" 0" ✅ Rainfall sufficient
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 4.3" 2" 2.3" 🚿 Regular watering
Dec 4.3" 1.3" 3" 🚿 Regular watering

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

Yam 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.

Yam needs ~6,949 GDD — county provides 8,583 GDD Good fit

Yam Planting Timeline — Zapata County, TX

Yam Planting Calendar

Activity When Date Range
Start Indoors December 23 Dec 23 – Jan 6
Transplant Outdoors February 10 Feb 10 – Feb 24
Direct Sow February 3 Feb 3 – Feb 24
Harvest August 11 Aug 11 – Dec 8

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

180–330 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

314 days in Zapata County

Growing Tips for Yam in Zapata County

Direct sow Yam outdoors after February 03 in Zapata County when soil has warmed and frost danger has passed.

With summer highs reaching 103°F in Zapata County, provide afternoon shade for Yam and water deeply in the morning.

Your 315.0-day growing season in Zapata County is tight for Yam (180.0-330.0 days to maturity). Start indoors and choose early-maturing varieties.

General growing tips

Plant tuber pieces in mounds of loose, rich soil. Provide sturdy trellising for climbing vines. Yams require a long, warm growing season of 8-11 months. Harvest when vines die back.

Companion Planting

Good Companions

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Yam in Zapata County, TX?

Zapata County is in Zone 9b with an average last frost of February 3. Plan your Yam planting based on this frost date — see the calendar above for exact timing.

What planting zone is Zapata County, TX?

Zapata County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 3 and first fall frost is December 14.

🌱

Your Zapata County Garden Planner — Free

A 24-page printable planner built for Zapata County (Zone 9b). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

Instant PDF download. No spam, unsubscribe any time.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Zapata County, TX. 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.