Grassy Weeds - St Augustine Lawn - Johnsongrass
BES-TEX Weed ID Guide · Grassy Weeds
Johnsongrass
Sorghum halepense
Common Name
Johnsongrass
Latin Name
Sorghum halepense
Family
Poaceae
Life Cycle / Type
Perennial · Grassy weed
What Is It?
Johnsongrass is a tall, aggressive perennial grassy weed with wide leaf blades, a prominent white midrib, and a coarse upright growth habit. It spreads rapidly by thick underground rhizomes and seed and is commonly found in lawns, pastures, fence rows, and disturbed areas. This is a perennial weed. Pre-emergent herbicides do not control existing perennial weeds.
Soil Temperature & Germination
Johnsongrass growth increases as soils warm in late spring and summer.
Above 65°F
Active growth begins
Above 75°F
Rapid growth and spread
Decision Question
Is the Johnsongrass visible above the soil right now?
NO
It has not emerged.
Pre-emergent may reduce new seedlings but will not control established plants.
Pre-Emergent Herbicide BMPWhy This Weed Comes Back
Aggressive rhizome system
Missed early intervention
Thin or stressed turf
Learn the Basics
A healthy, thick lawn is the best defense against weeds.
