Overview: Targeting weeds
When my wife and I bought our house, the lawn was filled with weeds. Dandelions and
ground ivy mostly, with a few generous patches of clover and thistles. I poured some
weed killer into a dial-up sprayer, hooked the sprayer up to my outdoor spigot,
doused the entire lawn, and an hour later I was done. Within a couple of days, the weeds were wilting,
and they didn't grow back after I mowed them. Not bad for an hour's worth of weed treatment!
While I don't claim to have the best-looking lawn on the block (my neighbor is a lawn fanatic!), it
is weed free. In this story, we'll show you how to kill your weeds in an hour or less. Although there are
hundreds of kinds of weeds, they all fall into one of three categories—broadleaf, annual grassy weeds
or perennial grassy weeds—and specific types of herbicides target each weed group.
Whether you want to eliminate weeds before they start growing again (early in the year is the best
time to attack weeds) or kill weeds that are already overtaking your lawn, we'll show you how. Most
of the weed treatments you need are available at home centers, and the others at garden centers. — Brett Martin, editor.
Kill broadleaf weeds: Early season
A broadleaf weed is any undesirable lawn plant that isn't a grass. The plants have actual leaves on stems, and contrary
to the name, many have narrow rather than “broad” leaves. Dandelions, plantain, ground ivy (creeping charlie)
and ragweed are a few of the most common broadleaf weeds.
Before broadleaf weeds start growing in the spring, apply a
product called Hi-Yield Turf & Ornamental Weed & Grass
Stopper Containing Dimension, which is a preemergent herbicide.
It kills weeds before they sprout from seed and even
kills some weeds that have just started to grow. Spread the
product on the yard between your first and third mowings in
the spring. The company says a single application will last a
full 120-day season. This is as close to a one-size-fits-all
magic bullet as you'll find for eliminating annual weeds. No
other product on the market will target both broadleaf and
annual grassy weeds and stop them from growing. It's available
at lawn and garden centers (call first to make sure). A 35-lb. bag treats up to 15,000 sq. ft.
Park your broadcast spreader over a tarp or on the driveway
(grains may leak out, and a heavy dose of herbicide on
the yard can kill even healthy grass). Fill the spreader (Photo
1) and distribute the herbicide evenly over your lawn.
Kill broadleaf weeds: Late season
If a few broadleaves pop up in the yard (you can always count
on a few dandelions), spot-kill them with a post-emergence
herbicide such as Ortho's Weed-B-Gon MAX (a 32-oz. bottle of
concentrate covers 16,000 sq. ft.). Look on the label for
“broadleaf killer” then check to see which weeds it targets.
Some broadleaf herbicides also kill crabgrass. There's no
need to treat the entire lawn, just the weedy areas. Don't let
them spread and create a bigger problem.
Premixed herbicides are OK if you have a small lawn and
only a few weeds. Otherwise, buy concentrates to mix yourself—
they're a better value. Wait until the temperature is
between 60 and 85 degrees F. (The herbicide vaporizes too
soon in high temps, and weeds don't grow fast enough in low
temps to absorb the chemicals.) Mix the herbicide with water
(follow the directions) and pour it into a small pump sprayer. Keep the nozzle 6 to 12 in. from the weed and
spray until the leaves are slightly wet (Photo 2).
Kill broadleaf weeds: Too late
If your lawn has lots of weeds scattered over
large areas, don't waste time spot-spraying individual
weeds. Killing the weeds is as quick and easy as spraying the
weedy area with a hose.
Pour a concentrated postemergence herbicide (the same
kind you used for spot-spraying) into a dial sprayer and
set the dial on the lid to the manufacturer's recommended
mixture (such as 2 tablespoons per gallon of water). Attach
the sprayer to a garden hose, turn on the water, and apply an
even treatment to the weedy areas in the yard (Photo 3).
Apply the herbicide when the weeds are actively growing in
the late spring and early summer. You don't need to drench
the weeds. A light misting will kill most weeds (if it doesn't,
give them a second dose in a week). Spray only on a calm day.
Even a slight breeze can carry vapors that can kill plants (anything
that kills broadleaf weeds will also kill flowers or decorative
plants and could harm trees, so watch for overspray).
Tip: Only spray the weedy
areas of the yard—
not the entire lawn.
You'll introduce less
herbicide into the
Kill annual grassy weeds: Early season
Annual grassy weeds sprout from seed each year. The weed dies in the fall,
leaving behind seeds that germinate the following spring. Crabgrass is the most
notorious grassy weed, but there are others, like yellow foxtail and nutgrass.
Use a preemergent herbicide to kill annual grassy weed seeds
in the spring before they germinate. Crabgrass preventer is
the most common, but you might as well apply a herbicide
containing Dimension in the spring because it also kills
broadleaf weed seeds. Crabgrass often thrives along sidewalks
and driveways because the ground is warmer there, so be sure
to apply herbicide in those areas.
Kill annual grassy weeds: Late season
The best way to handle a few scattered annual grassy weeds is
to spot-kill them with a postemergence herbicide that's formulated
for grassy weeds, such as Ortho's Grass-B-Gon. Look for Grass Weed Killer or Crabgrass Killer
on the label (Crabgrass Killer kills other grassy weeds too).
Mix the concentrated herbicide with water (per manufacturer's
directions), then pour the mixture into a handheld
sprayer. Spray the individual patches of weeds (Photo
1). To ensure that
there's plenty of plant
material to absorb the
weed killer, don't mow the weeds just before applying the
herbicide or for three days after. If you don't kill annual
grassy weeds now, you can expect them to seed and produce
even more weeds next year.
Tip: Always read the
before applying to
make sure it will
kill the targeted
weeds and not
harm your lawn.
Kill annual grassy weeds: Too late
There's only one remedy for yards taken over by grassy
Weeds—spray the entire lawn with a postemergence herbicide
(like the ones used in the “Late” stage). Mix the concentrate
with water in a pump sprayer (Photo 2).
Spray the yard with the herbicide in the late spring or summer.
Apply just enough to get the weeds slightly wet. The
weeds should start to die within five to seven days. Spot-kill
any weeds that are still growing after seven days.
Kill perennial grassy weeds: Early and late season
Perennial grassy weeds come back every year, just like your lawn grass, and are the
toughest weeds to deal with. That's because the herbicides that kill these weeds will
also kill your grass. Perennial grassy weeds like Dallis grass and quack grass have
deep, expansive root systems that make it impossible to kill them by pulling them out.
Quack grass is easy to identify—three or four days after you've mowed your yard, quack
grass will be noticeably taller than the surrounding grass
To spot-kill the weeds, apply a nonselective herbicide, such as
Roundup. Nonselective herbicides
kill plants and weeds alike, so it has to be applied to the individual
weeds by hand. Wearing cloth gloves over plastic
gloves, wipe the herbicide directly onto the weed (Photo 1).
Don't worry about covering every single blade. As long as you
get most of them, the herbicide will absorb into the weed. It'll
take seven to ten days before the weed starts to die. If it's not
dead after two weeks, wipe on a second treatment.
The solution is the same later in the year. But the longer you
wait, the more work you'll have since these grasses continue to
spread all spring and summer. The herbicide is most effective
early in the season when grasses grow the fastest. As the weeds
take root and become sturdier, they may require more applications
to fully kill.
Back to Top
Kill perennial grassy weeds: Too late
Once there are too many weeds
to spot-treat by hand, it's time
for draconian measures. Kill
everything and start over.
Spray a nonselective herbicide
on the weedy area
(Photo 2). Wait two weeks. If
they're not dead, spray them again.
Once the weeds are dead, mow
them as short as possible. After
spraying the herbicide, wait 14 days
to plant new grass so the herbicide
won't kill it.
Photo 1: Wet the bare spot
Photo 3: Spread a faster growth mix
How to Restore Bare Spots
Killing large patches of
weedy areas is going to leave
bare spots in your yard that
will need to be replanted
with grass. The best times to
reseed are the spring or fall
when the temperature is 60
to 70 degrees F. To start,
water the bare spot until it's
wet to a depth of at least
3-1/2 in. Water at intervals
throughout the day (for
about 15 minutes every two
to three hours) rather than
continuously. With constant
soaking, the water just runs
off. Check the depth of the
water penetration by digging
into the ground and lifting up
the soil (Photo 1). You'll be
able to see or feel how deep
the water has seeped in.
Make a series of 3/8-in.-
deep recesses in the ground,
1 in. apart, with a square-head
shovel. Spread the grass
seed over the bare spot. Then
flip over a garden rake and
use the “knuckles” to cover
the seed with soil (Photo 2).
Lightly water the area in the
morning and evening until
the grass starts to grow in.
If you want the seed to
grow fast, plant Scotts
PatchMaster, which is grass seed
with fertilizer and mulch to
keep the seed from drying. After making the recesses
in the ground, spread PatchMaster seed over the bare
spot (Photo 3). Water twice daily.