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When to Plant Sweet Potatoes in San Patricio County, TX

San Patricio County, Texas Zone 9b May

Top priorities for San Patricio County, Texas gardeners in May

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

Avg. last frost February 12
Avg. first frost December 9
Soil temp (4") 73°F
Watering Low
Pest pressure High
Daylight 13.4 hrs
  1. Harvest sweet potatoes as they ripen

    Don't tug. Use scissors or pruners for clean cuts — torn stems invite disease.

A few tasks this May that'll pay off in June
  • First harvests: 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.

San Patricio County, Texas is in USDA Zone 9b. The average last spring frost is February 12 and the first fall frost is December 9, giving you a growing season of approximately 300 days.

At an elevation of 2,449 feet, San Patricio County receives approximately 54.7 inches of rainfall annually with predominantly loam soil. Summer highs average 100°F, so Sweet Potatoes may need afternoon shade and extra watering during peak heat. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Sweet Potatoes root diseases.

San Patricio County, TX (Zone 9b) Year-round
300 days
Last Spring Frost February 12
300 growing days
First Fall Frost December 9
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San Patricio County Soil Profile

Soil Type

Loam

Soil pH

6.8-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (168 days to spare)
Start indoors: Dec 9 Transplant: Jan 27 🍅 Harvest: Apr 28 – Jun 16
Recommended (50%) ✓ Fits season (153 days to spare)
Start indoors: Jan 1 Transplant: Feb 19 🍅 Harvest: May 21 – Jul 9
Safe Start (90%) ✓ Fits season (140 days to spare)
Start indoors: Jan 27 Transplant: Mar 17 🍅 Harvest: Jun 16 – Aug 4

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 San Patricio County

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

Soil pH

Your soil pH (6.8–7.2) is more alkaline than Sweet Potatoes prefers (5.5–6.5). Add sulfur or peat moss to lower pH.

Soil Texture

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

Organic Matter

Organic matter is low (1.9%). Add 2-3 inches of compost before planting Sweet Potatoes.

How to Plant Sweet Potatoes

1"
Planting Depth
15"
Between Plants
24"
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 634 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 1.5" 0" ❄️ Dormant
Feb 4.3" 1.7" 2.6" 🚿 Regular watering
Mar 4.3" 3.8" 0.5" 💧 Light watering
Apr 4.3" 6.4" 0" ✅ Rainfall sufficient
May 4.3" 8.5" 0" ✅ Rainfall sufficient
Jun 4.3" 8.1" 0" ✅ Rainfall sufficient
Jul 4.3" 7.5" 0" ✅ Rainfall sufficient
Aug 4.3" 5.6" 0" ✅ Rainfall sufficient
Sep 4.3" 5" 0" ✅ Rainfall sufficient
Oct 4.3" 3.1" 1.2" 💧 Light watering
Nov 4.3" 2" 2.3" 🚿 Regular watering
Dec 4.3" 1.4" 2.9" 🚿 Regular watering

Water needs are for active growing months only (Feb–Dec in San Patricio 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 ~2,625 GDD — county provides 7,525 GDD Excellent fit

Sweet Potatoes Planting Timeline — San Patricio County, TX

Sweet Potatoes Planting Calendar

Activity When Date Range
Start Indoors January 1 Jan 1 – Jan 15
Transplant Outdoors February 19 Feb 19 – Mar 5
Direct Sow February 12 Feb 12 – Mar 5
Harvest May 21 May 21 – Jul 9

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

Month-by-Month Timeline

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

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 5.5–6.5 · Your soil: too_alkaline

🗺️ USDA Zone

Zone 9b

📆 Growing Season

300 days in San Patricio County

Growing Tips for Sweet Potatoes in San Patricio County

Direct sow Sweet Potatoes outdoors after February 12 in San Patricio County when soil has warmed and frost danger has passed.

With summer highs reaching 100°F in San Patricio County, provide afternoon shade for Sweet Potatoes and water deeply in the morning.

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 San Patricio County, TX?

San Patricio County is in Zone 9b with an average last frost of February 12. Plan your Sweet Potatoes planting based on this frost date — see the calendar above for exact timing.

What planting zone is San Patricio County, TX?

San Patricio County, Texas is in USDA Hardiness Zone 9b. The average last spring frost is February 12 and first fall frost is December 9.

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Your San Patricio County Garden Planner — Free

A 24-page printable planner built for San Patricio 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.

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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 San Patricio 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.