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When to Plant Black Beans in Knox County, TX

Knox County, Texas Zone 8a May

Top priorities for Knox County, Texas gardeners in May

If you only do a handful of things in the garden this May, make it these. They're sequenced around your zone's frost timing.

Avg. last frost March 24
Avg. first frost November 12
Soil temp (4") 64°F
Watering Low
Pest pressure Moderate
Daylight 13.7 hrs
Coming up in June — start thinking about
  • First harvests: black beans

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Black beans are a warm-season legume producing small, dark, protein-rich beans that are a staple in Latin American and Caribbean cuisines.

Knox County, Texas is in USDA Zone 8a. The average last spring frost is March 24 and the first fall frost is November 12, giving you a growing season of approximately 233 days.

At an elevation of 1,847 feet, Knox County receives approximately 51.2 inches of rainfall annually with predominantly loam soil. Summer highs average 93°F, providing good warmth for Black Beans during the growing season. Ample rainfall means less supplemental watering, but ensure good drainage to prevent Black Beans root diseases.

Knox County, TX (Zone 8a) Long season
233 days
Last Spring Frost March 24
233 growing days
First Fall Frost November 12

Knox County Soil Profile

Soil Type

Loam

Soil pH

6.4-7.2

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (90 days to spare)
Transplant: Mar 17 🍅 Harvest: Jun 16 – Aug 4
Recommended (50%) ✓ Fits season (93 days to spare)
Transplant: Mar 24 🍅 Harvest: Jun 23 – Aug 11
Safe Start (90%) ✓ Fits season (86 days to spare)
Transplant: Apr 13 🍅 Harvest: Jul 13 – Aug 31

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 Knox County

How your county's soil matches Black Beans's growing requirements.

Soil pH

Your soil pH (6.4–7.2) is within Black Beans's preferred range (6.0–7.5).

Soil Texture

The loam soil in Knox County is excellent for Black Beans — good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

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

How to Plant Black Beans

1"
Planting Depth
15"
Between Plants
24"
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 160 gal / 100 sq ft

Monthly Watering Guide for Black Beans

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

Month Black Beans Needs Rainfall You Supplement Action
Jan 1.3" 0" ❄️ Dormant
Feb 2.1" 0" ❄️ Dormant
Mar 4.3" 3.2" 1.1" 💧 Light watering
Apr 4.3" 6.4" 0" ✅ Rainfall sufficient
May 4.3" 6.7" 0" ✅ Rainfall sufficient
Jun 4.3" 7.3" 0" ✅ Rainfall sufficient
Jul 4.3" 6.5" 0" ✅ Rainfall sufficient
Aug 4.3" 5.9" 0" ✅ Rainfall sufficient
Sep 4.3" 5.4" 0" ✅ Rainfall sufficient
Oct 4.3" 3.3" 1" 💧 Light watering
Nov 4.3" 1.8" 2.5" 🚿 Regular watering
Dec 1.3" 0" ❄️ Dormant

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

Black Beans 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.

Black Beans needs ~2,074 GDD — county provides 4,601 GDD Excellent fit

Black Beans Planting Timeline — Knox County, TX

Black Beans Planting Calendar

Activity When Date Range
Direct Sow March 31 Mar 31 – Apr 21
Harvest June 30 Jun 30 – Aug 18

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

Month-by-Month Timeline

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

Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Only during dry spells

📅 Days to Maturity

90–120 days

🧪 Soil pH

Needs 6–7.5 · Your soil: ideal

🗺️ USDA Zone

Zone 8a

📆 Growing Season

233 days in Knox County

Growing Tips for Black Beans in Knox County

Direct sow Black Beans outdoors after March 24 in Knox County when soil has warmed and frost danger has passed.

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

General growing tips

Direct sow after last frost. Provide support for climbing varieties. Allow pods to dry fully on the vine before harvesting. Thresh dried pods by hand or in a pillowcase.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Black Beans in Knox County, TX?

Knox County is in Zone 8a with an average last frost of March 24. Plan your Black Beans planting based on this frost date — see the calendar above for exact timing.

What planting zone is Knox County, TX?

Knox County, Texas is in USDA Hardiness Zone 8a. The average last spring frost is March 24 and first fall frost is November 12.

🌱

Your Knox County Garden Planner — Free

A 24-page printable planner built for Knox County (Zone 8a). 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 Knox 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.