Cobb County Extension Service
Common Winter Weeds
By Melissa Guidice
Horticultural Program Assistant
Winter-Ahh! A season of little maintenance for the turf: few diseases, weeds and the grass doesn’t grow. Snap out of it! That was a dream!
Winter is when weeds that were not controlled in the fall show up-in a big way. Fall is when pre-emergent herbicides should be applied to control annual bluegrass and selected winter annual broadleaf weeds. The recommended dates for Cobb County are September 15 to October 15.
Late fall, November through February is when post-emergent herbicides should be applied to continue weed control.
Some of the winter weeds that arrive in lawns and beds are: annual bluegrass, carolina geranium, chickweed-common, chickweed-mouseear, clover-large hop, corn speedwell, hairy bittercress, henbit, purple cudweed, wild garlic and wild onion. Click on names below to see the weeds or click here to see a full color page of the weeds.
Annual Bluegrass This a small tufted to clumped annual.
The leaf blade is smooth on both surfaces,
with 2 distinct clear lines, 1 on each side of the
midrib. Leaf tip is keeled or boat-shaped. Light green to
whitish spikelets that lack cottony hairs & are arranged
on branches @1-2 per node & in dense open flower
clusters. Reproduction by seed
Carolina Geranium It is a diffusely branched, semi-erect annual. Stems are
greenish-pink to red & densely hairy. Leaves have long
petioles, are hairy & dissected into variously divided
segments, with blunt toothed margins. The flower is
pink to purplish with 5 petals. A 5-part fruit capsule
that forms a “stork’s bill” up to ˝” long. Reproduction
by seed
Chickweed-Common This a mat forming annual with numerous branched
stems. The leaves are opposing, smooth & the shape is
oval to broadly elliptical. Upper leaves are without
petiole & lower leaves have a sparsely hairy long petiole.
Stems have vertical lines of hair. White flowers are in
small cluster @ends of stems & have 5 deeply notched
petals. Reproduction by seed
Chickweed-Mouseear Annual that branches & forms mats. Opposing leaves,
that are densely hairy & the leaf shape is oval to
elliptical. Slender stems that are covered by dense hairs.
White flowers that are arranged in clusters @ stem ends.
The 5 Petals are slightly notched. Reproduction by seed
Clover –Large Hop Prostrate annual with hairy stems & alternating leaves.
There are 3 leaflets, that are serrated from mid-blade to
the tip. The numerous (20-30) bright yellow flowers
are loosely clustered on long stalks that are attached at
leaf axils. Reproduction by seed
Corn Speedwell This a low-growing, freely branched annual. The
lower leaves are round to oval, with toothed margins
& prominent veins. The upper leaves are of a linear
shape. The leaves & stems are finely haired. The light
blue flowers are nearly stalk less. Heart-shaped seed
capsules with a line of hairs on the outer edge.
Reproduction by seed
Hairy Bittercress This annual forms a rosette of dark green & dissected
leaves. The leaf segments are rounded to wedge-shape
with lower petioles hairy near base. White, densely
clustered flowers at the ends of stems have 4 petals.
Fruit is formed into a flattened capsule that is 10X
longer than broad. Reproduction by seed
Henbit This a sparsely hairy annual with 4-sided stems, that
are tender with a greenish to purplish color. This weed
is similar in appearance to purple deadnettle, but the
upper leaves lack petioles. Opposing leaves that are
broadly egg-shaped & with bluntly toothed margins &
prominent veins on the underside. Flowers are reddish-purple, with darker coloring in spots on the lower petal
& arranged in whorls. Reproduction by seed
Cudweed A & B This annual or biennial forms a basal rosette of leaves.
The stems are highly branched from the base of the
plant. The stems & underside of leaves also have
soft, velvet-like hairs. The upper leaves are a dull green
color. The rosette & lower stems leaves are spatula-
shaped, with blunt tips. Rosette upper leaves are
reduced in size. Tannish-white flowers form clusters at
upper leaf axils. The bracts surrounding the flower
clusters are pink or purple in color. Reproduction by
seed
Wild Garlic & Onion This is a perennial with slender & hollow cylindrical
leaves. The leaves occur on the flowering stem up to
half the height of the plant. Bulbs form underground
& bear offset bulblets that are flattened on one side &
enclosed by a membrane. Greenish-white flowers are
small & on short stems above aerial bulbils.
Reproduces by seed, aerial bulbils & underground
bulblets.