Last week in between the rain showers, I finally had the opportunity to tend to
my flower beds. While not the most enjoyable outdoor task, weeding is
necessary. Remember the saying, “one year of seeds equals seven years of weeds.” That is enough motivation to get me to pull weeds in this heat, humidity and
mud.
A weed is defined as “a plant out of place.” Weeds compete with desirable plants for light, nutrients, space and water.
Weeds also harbor insects (mosquitoes) and diseases. It is critical, especially
at this time of year, to control weeds in the garden.
There are many weeds that develop at this time of year. Some of the ones I had
the pleasure of pulling included smartweed, lambsquarter, foxtail and red root
pigweed. What gardeners dread and these weeds have in common are that they grow
rapidly, flower quickly and produce thousands of seeds.
Proper identification of a weed and understanding its growth cycle is necessary
to its control. It is helpful to know if the weed is an annual, biennial or
perennial. Annual weeds — which include crabgrass, smartweed, foxtail, buttonweed and lambsquarter — come back from seed each year. Biennial weeds live two years, producing seed
the second year. Burdock is one example of a biennial weed. Perennial weeds
come back year after year from the same root. Dandelions, quackgrass and
creeping Charlie are dreaded examples of perennial weeds.
Weed control options include mulching, ground covers, herbicides and the
not-so-fun hand pulling.
Mulch. Mulching is my favorite option for weed control. Mulches help to suppress seed
germination, conserve soil moisture and keep the soil temperature more even. In
vegetable gardens, mulch keeps the fruits off the ground. Most plants will
benefit from a two- to three-inch layer of mulch applied around the plant. To
avoid crown rot, keep mulch away from the base of a plant. Mulches control
weeds by preventing light, which is needed for germination, from reaching the
soil surface. Mulches can either be organic or inorganic. Organic mulches
include compost, shredded leaves, wood chips, dry grass clippings, newspaper
and pine needles. Inorganic mulches include fabric weed barrier, black plastic
and rock.
Ground covers. Bare patches of soil will invite weed seed germination especially in sunny
spots. Plant a ground cover to prevent weeds from taking over the bare soil
area. These can be plants such as hosta or vinca in a shady area, or a thyme or
low-growing sedum in full sun.
Hand removal. This method of weed removal includes hoeing, tilling, mowing and hand pulling
with a tool such as a garden knife. Cut off weeds just below the soil surface
with a sharp hoe. Remember, the roots of desirable plants are just below the
soil surface and can be easily damaged. The ideal method to use between
vegetable garden rows (provided you have left ample space between rows) is
shallow cultivation with a rotary tiller or manual-powered rotary cultivator.
One rule of thumb: weeds are easiest to remove when the soil is moist but not
muddy. Hand removal is easy if you start when the weeds are small and tackle
one small area at a time.
Herbicides. Pre-emergent herbicides keep the seed from emerging through the soil. A common
pre-emergent herbicide for the home garden is trifluralin, sold as Treflan or
Preen. Post-emergent herbicides control a weed after it has emerged from the
soil. Glyphosate, sold as Roundup or Kleenup, is a nonselective herbicide for
controlling perennial weeds. Nonselective means it will kill any plant. To
protect your desirable plants use a foam paintbrush to apply the glyphosate.
Herbicide usage is not recommended in vegetable gardens.
When using any chemical, it is important to read and follow all label
directions. And pay attention to the appropriate time to apply the chemical or
you have wasted your time and money.
For more information on weed identification and control of common weeds, visit
University of Illinois searchable Web sites at http://weedid.aces.uiuc.edu and
Weed Identification, http://weeds.cropsci.illinois.edu/ weedid.htm.
Contact Jennifer Fishburn at fishburn@illinois.edu.
This article appears in Jul 2-8, 2009.
