By Wayne McLaurin
University of Georgia
Many bothersome weeds were introduced to North America as food sources. It's possible to add young tender dandelions, chickweed, pepper cress or shepherd's purse to salads.
Eating them, while interesting, doesn't provide a reliable way to control weeds. Munching on them does have psychological and ecological value. It reminds us that every plant we eat or use was developed from a wild plant.
No scientist has ever created a food plant in a lab. But many have worked to enhance the edible and useful characteristics of thousands of wild plants. We owe our lives to weeds.
Of course, that fact may not be very comforting when you're looking at an overgrown garden.
Two problems confront gardeners when controlling annual weeds. The seeds persist for a long time in soil, and they come up at irregular intervals. Both traits make them hard to control.
Annual weeds grow seeds in prodigious quantities. Then the wind, birds and animals and the plant's own ability to expel and propel the seeds distributes them everywhere. The scattered seeds will germinate and new plants grow from them whenever the soil is dug or disturbed.
Many gardeners have been frustrated by the flush of green across a newly-raked garden. Clean it off, turn the soil over, and within a week, hundreds of weed seeds will germinate.
Persistence and method together, though, will help control annual weeds.
Meet the enemy face-to-face
The main enemy is the seed production -- that's the annual weed's primary weapon. If you can keep it from producing seeds, by some method of weed birth control, you can reduce, if not eliminate, this continuing problem.
No, you'll never really eliminate weeds. But all weeds, no matter what their life cycles, are easier to control as small, immature plants.
The first key is mechanical scuffling of the soil to kill newly-emerged plants. To control weeds by some form of hoeing, you need to keep watch and hoe as often as needed to keep the emerging weeds down before they go to seed.
A weekly "weed walk" through the garden with a scuffling tool in hand can reduce time and effort later. The old saying, "One year's seeds, seven years' weeds," reflects the persistence of weed seeds.
Annual weeds -- all weeds -- tend to hide out under plants or disguise themselves as garden ornamentals. Lift plant edges and look closely for sneaky seedlings.
Besides hoeing, another way to control weeds is to smother them. This removes chances for the hidden seeds to get to light and germinate.
Using ground-cover plants in a garden is a good way to reduce weed problems. A well-established stand of low perennial plants will shade out weeds.
But ground covers must be weeded as they fill in, and it may take three years of persistent care before their branches offer substantial weed protection.
Covering the ground with 2 to 3 inches of any organic mulch, such as compost, leaves, aged sawdust or commercial compost, will help keep thousands of annual weed seedlings from coming up.
It's possible, too, to use one of the weed-prevention geotextiles made of a woven, synthetic fiber. These allow water and air to penetrate but won't allow light to the weeds.
Put mulch on top of these textiles for best appearance. They last for years if not torn by careless digging.
These textiles work more to the advantage of ornamental plants than solid black plastic does. Black plastic doesn't allow air or water to penetrate. This can damage the plant roots' health.