daylily bed is overrun with Quackgrass. We have tried repeated
hand weeding of this white-rooted spreading grass, but it keeps coming
back. Do you have any suggestions for getting rid of Quack grass?
For those of you who have never had the pleasure of dealing with
quackgrass (Elytrigia repens),
it one of the most difficult weeds to manage. It spreads by tough,
pointed underground stems (rhizomes). Any little piece of rhizome
left behind will grow into a new plant. Quackgrass rhizomes often
grow right through the fleshy roots of plants such as daylilies. Fluazifop-P-butyl, which is sold under trade names such as Ortho's
Grass-B-Gon or PBI Gordon's Ornamec, is labeled to remove quackgrass
from daylily beds.
Herbicides for Grassy Weeds
A selective herbicide that kills grassy weeds
without damaging broadleaf plants, it is most effective in spring or
early summer when quackgrass is actively growing and not more than
6-10 inches tall. You may still get some control by applying it in
late August or early September.
At that time of year, plants are
moving the carbohydrates produced through photosynthesis down to
store in their roots so they have enough energy to push new growth
next spring. Late summer and early fall is the best time to kill
many troublesome perennial weeds.
Grassy weeds are challenging in ground
covers like these spreading junipers. This homeowner has
the "triple-whammy" -- fighting grass plus wild onions and
Other Options for
weeds in Daylilly Plantings
You also have the option of lifting all your daylilies in
mid-September. Inspect their roots for quackgrass rhizomes and
remove any that have grown through. Then you can pull or dig the
remaining quackgrass plants from the bed and replant your daylilies.
Instead of digging it out, you can spray the quackgrass left in the
bed with Roundup (glyphosate), a non-selective, systemic herbicide
that kills most plants. It takes two weeks for Roundup to thoroughly
kill weeds, roots and all, so you would have to wait to replant your
daylilies. If you disturb weeds that have been sprayed with Roundup
prematurely, it may not have a chance to kill the roots completely.
Whichever approach you take, do not be surprised if you see some
re-sprouts next spring. You can spot treat them with Grass-B-Gon or
pull them out by hand. The trick with hand weeding is to stay on top
of it. You can exhaust a weed's root reserves if it doesn't exhaust
Science of Weeds
Using Weed Killer
When African Violets stop blooming