Chicago Daily Herald, IL
10-14-07
Sneaky weeds survive winter and return with a vengeance
By Jan Riggenbach, Midwest gardening
To flower gardeners who grow heat-loving annuals such as marigolds and
impatiens, the term "winter annual" probably sounds like an oxymoron.
Those of us who routinely battle weeds such as chickweed, henbit and creeping
speedwell, though, know all too well about winter annuals. These small but
sneaky weeds sprout in autumn when we're not paying attention, and survive the
winter as small seedlings. In early spring, they bloom in profusion, then quickly
set and drop their seed.
Winter annuals are a problem not only in no-till farm fields but also in perennial
beds, lawns or any other area that isn't regularly cultivated. The plants bloom and
die by early summer, but they leave behind thousands of seeds to ensure the
weeds will reappear in even greater numbers the following fall.
The trick in controlling winter annuals is to pull them out of the garden in fall,
before they have a chance to bloom.
Although not a winter annual, another weed to control in autumn is ground ivy
(Glechoma hederacea), a common pest that looks a lot like henbit. Also known
as creeping Charlie, ground ivy is a hardy perennial that's difficult to kill. Like
henbit, it has tubular, lavender-blue flowers and rounded, scalloped leaves.
Unlike henbit, though, which has an easy-to-pull taproot, ground ivy has vining
stems that creep along the ground, making new roots in every spot where a stem
joint touches the ground.
Ground ivy is actually a pretty little ground cover plant, prospering in shady
areas. I know some people who, after giving up on growing grass in the shade,
just let ground ivy serve as the walking paths between woodland flower beds.
In gardens and lawns, though, ground ivy is not welcome. Anything that kills
ground ivy is so harsh that experts generally recommend pulling it out of gardens
by hand. You can resort to chemicals in the lawn, though, and autumn is the best
time to apply them. A chemical spray that contains 2,4 D will work, although two
applications are often necessary.
20 Mule Team Borax is another option. Be careful to follow the formula worked
out by researchers at Iowa State University, because too much can kill the
grass. Dissolve 10 ounces of 20 Mule Team Borax in 21⁄2 gallons of water. Use
that amount of solution to treat 1,000 square feet of lawn.
You can find much more information on controlling ground ivy at
www.ipm.iastate.edu/ipm/hortnews/.
Another way to wage war against ground ivy is by fertilizing your lawn with a
slow-release fertilizer this fall. Research at Purdue University shows that a wellfertilized lawn favors lawn grasses, not ground ivy.