University of Maryland Extension

Lawn Weed ID and Management

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Before attempting to manage lawn weeds, identify them first by using the images below or submit your question and digital photos to Ask an Expert.

Why Do Weeds Appear in Lawns?

Improper mowing practices, frequent, shallow watering, not fertilizing correctly, compacted soil, poor soil conditions, and bare spots. These factors contribute to the decline of the grass allowing weeds to move in.

Resources        

 Broadleaf Winter Annual Weeds

Seeds germinate from late summer through fall. Weeds overwinter and continue to grow in early spring. Treat with a broadleaf postemergent herbicide applied when the weeds are actively growing in the spring. The exception is chickweed which can be prevented with a preemergent applied in early September before it germinates. However, you would then not be able to sow grass seed.

flowering chickweed
Chickweed
dead nettle with purple flowers
Deadnettle
hairy bittercress with tiny white flowers
Hairy bittercress

henbit and flowers
Henbit

knawel foliage
Knawel

flowering shepherd's purse
Shepherd's purse 
(photo U. Mass Amherst) 

speedwell with purple flowers
Speedwell (Veronica)

Broadleaf Summer Annual Weeds

Seeds begin to germinate as soils begin to warm up in early spring and continue to germinate throughout the growing season. Annual weeds complete their entire life cycle in a single growing season. However, some of these weeds can also be perennials or biennials. Treat with a broadleaf postemergent herbicide applied when the weed is actively growing.

black medic and yellow flowers
Black medic

carpet weed
Carpetweed
low growing lespedeza
Common lespedeza
knotweed foliage
Knotweed

mallow foliage
Mallow

prostrate spurge foliage
Prostrate spurge (photo 
Jack Harper Penn. State)

purslane weed
Purslane

 

Broadleaf Perennial Weeds 

Perennials are persistent from year to year. They reproduce by seed and also by vegetative means. This is the largest group of weeds. They range from weeds that are easy to eliminate, to some of the most difficult to control. Treat with a broadleaf postemergent herbicide applied when the weed is actively growing.  For difficult to manage weeds, like creeping Charlie and Indian strawberry, a spring and fall application of an herbicide is recommended. A fall herbicide application can be effective because at that time of year, what is applied to the leaves will be translocated to the root system.   

curly dock foliage
Broadleaf & curly dock

broad leaf plantain
Broadleaf plantain
 

 bulbous buttercup roots
Buttercup (bulbous)

cinquefoil foliage
Common cinquefoil 

 common dandelion
Dandelion

ground ivy with purple flowers
Ground ivy (Creeping
Charlie)

Indian strawberry and berries
Indian mock strawberry

chickweed foliage
Mouse-ear chickweed

oxalis foliage
Oxalis (woodsorrel)

sheep or red sorrel foliage
Sheep or red sorrel

common white clover
White clover

wild garlic or onion
Wild garlic and wild onion
flowering wild violet
Wild violet
yarrow foliage
Yarrow

Grassy Winter Annual Weeds

Seeds germinate in late summer to early September. Prevent with a preemergent herbicide applied in early September before the seeds germinate.

annual blue grass
Annual bluegrass

Grassy Summer Annual Weeds

Seed germination begins in early to mid-spring, when soil temperatures have risen to 55° - 60° F. for about a week. In Central Maryland; this is typically mid-March through mid-April. Seeds continue to germinate in the summer, and plants are killed by the first frost. Prevent with a preemergent herbicide applied prior to seed germination. Click for information on using corn gluten as a preemergent herbicide. 

young crabgrass
Crabgrass

low growing goosegrass
Goosegrass

patch of Japanese stiltgrass
Japanese stiltgrass **
Invasive

Grassy Perennial Weeds/Sedges

Are some of the most difficult weeds to control in a lawn. There are very few selective herbicides labeled to manage these types of weeds.

bermuda or wire grass
Bermudagrass or wiregrass

clump of dallisgrass
Dallisgrass
nimblewill patch
Nimblewill
orchardgrass patch
Orchardgrass
quackgrass and root system
Quackgrass

 light green roughstalk bluegrass
(photo Perdue Un. Turf. Program)
Roughstalk bluegrass (Poa
trivialis) 


 

Sedges

Kyllinga and seedheads
Kyllinga

clump of yellow nutsedge
Yellow Nutsedge

Moss 

Is actually an
attractive groundcover
in areas where grass
does not grow well or planted as a
lawn alternative

green moss

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