For Release On Or After 10/19/12

There are many reasons why we shouldn’t let weeds grow in our landscapes. Weeds, particularly in flowerbeds, shrub plantings and ground covers, cause landscapes to look unattractive and neglected. Even if the lawn is nicely mowed and edged and everything else looks neat, weedy beds ruin the appearance of the landscape. Weeds in turfgrass diminish the even, uniform look we desire from our lawns.

Weeds can also be destructive when they compete with landscape plants for light, water and soil nutrients. Allow a weedy vine to grow over a shrub for several months and you will find that sections of the shrub have been shaded out and killed. And some weeds, if left unchecked, can out-compete turfgrass and damage the lawn, requiring repair work.

I frequently hear the comment, “It seems like this weed just suddenly became a major problem.” If we are honest with ourselves, however, we have to admit that weed problems do not happen overnight or in a matter of days or even a few weeks. Serious weed problems occur primarily when there is chronic neglect and when not enough effective effort is made to bring them under control.

When someone tells me, “I just can’t get rid of this weed,” I generally counter with, “Nothing can grow in your landscape unless you let it.” It’s mostly a matter of whether or not you are willing (or in some cases able) to put in the time, money and effort needed to do the job.

One clear truth is this – the more time and effort you put into managing a weed problem, the easier it gets. Over time, weed problems are greatly reduced in landscapes where weed control is done frequently and effectively.

Individuals who allow weeds to get way out of hand before doing anything have a much harder time. People tend to put in a big effort at that point to clear things out. But if you sit back and allow the weeds to return, everything you worked so hard to achieve will disappear; you will simply have spun your wheels and made little real progress.

Staying on top of something rather than letting it go until it becomes a major problem is not an earth-shaking revelation. Still, it’s the best advice you can get on weed control. The very best cure for weed problems is a liberal dose of regular attention.

That said, you also want to make sure that when you make an effort at weed control, you are doing the most efficient and effective things. We employ two basic techniques in controlling weeds – physical and chemical. Both techniques include preventative and corrective methods. And you will not get perfect control with any technique.

Mulches – leaves, pine straw, newspaper and other materials – and landscape fabrics are preventive physical methods used in beds. These are applied to weeded areas to keep weeds from growing back. Hand weeding and hoeing are corrective physical controls done to deal with actively growing weeds.

There are some misconceptions about how mulches work. Mulch is not a literal barrier that keeps weeds from growing. The purpose of mulch is to block light from reaching the soil surface.

Virtually all weed seeds need light to stimulate germination. When mulch blocks light from reaching the soil surface where the weed seeds are, they won’t sprout and grow. To accomplish this, the mulch needs to be thick enough – at least to a depth of 2 inches. Mulches will NOT prevent weeds from growing from bulbs or rhizomes.

Mulches applied to and maintained at the proper depth will help reduce problems with annual weeds that grow from seeds, such as chamber bitters (gripe weed), spurge, annual bluegrass and chickweed. Perennial weeds growing from rhizomes, such as Bermuda grass and torpedograss, or bulbs, such as nutsedge or oxalis, will grow through mulch.

Landscape fabric or weed-barrier fabric will do more to suppress these perennial weeds. Landscape fabric is unattractive in beds and is generally covered with an organic mulch, such as pine bark or pine straw, to improve appearance.

Once weeds are up and growing, hand weeding or hoeing does an excellent job of controlling weeds if you do it regularly – at least once a week. As long as you are not dealing with tough, perennial weeds, hand weeding combined with a 2-inch mulch will keep most beds attractive and not work you to death.

Annual weeds can usually simply be pulled out. This is generally easier after watering or a rain. Hoes cut off weeds at or just below the soil surface and generally work well on annual weeds. But perennial weeds will simply resprout from their below-ground parts, and that makes hoeing a poor control for them. Weeds with bulbs or rhizomes also must be dug up to remove the below-ground parts.

Herbicides are generally an important part of weed control in most landscape situations. If you decide to use herbicides or weed killers, you need to take your time and make sure you know the right herbicide to use in a situation and how to apply it properly. Contact your local LSU AgCenter parish office for information on weed control and herbicide recommendations.