As we all know, one of the most stubborn yard and garden weeds is the dandelion. Are you tired of doing the same old weed control chores for dandelions and other weeds every year? Dandelion and other weed problems in the lawn can be greatly minimized by watering and mowing the grass to encourage its natural competitiveness. Because dandelions are so good at what they do, and there are so many seeds that blow in from outside your property, nothing you can do will totally and permanently eliminate dandelion problems. However, you can greatly reduce the number of dandelions and other weeds that are able to take root in your yard by helping your grass plants to develop deep, healthy root systems that can compete well with weeds. In nature, grasses are more competitive than most weeds, especially annual weeds and perennials with roots that do not grow as deeply as roots of healthy, deep-rooted grass. Good watering, mowing, and soil care practices can help a great deal.
Plant roots will grow where the water is; if you water turf every other day for one or two hours, the water will penetrate only to a shallow depth. Grass roots will remain in that area, producing shallow-rooted turf that can not compete well against weeds, diseases, insects, heat, and drouth. Germinating weed seeds will soon develop roots that will outcompete the grass roots and you have lost the battle. To help grass develop deep, strong roots, water deeply and infrequently, applying enough water that it soaks 6-8 inches deep. Some of our popular models of sprinklers can take up to 10 hours to get moisture this deep in the ground! In clay soils, watering might have to be broken into several back-to-back sessions. You will know it is time to water again when the top inch of soil has dried out. It can take about seven to ten days for the top inch of soil to dry out if water was allowed to soak 6-8 inches deep. To determine how long to leave your particular watering system turned on (even if it is just a hose-end sprinkler) to get water to soak this deep, turn the system on for one hour. Shut it off and wait two hours, to give moisture time to soak into the soil. Using a shovel or soil probe, dig to see how far the moisture has seeped. You then know how long you must leave the sprinkler in one place to apply one inch of water. For example, if the moisture has seeped two inches deep, you know to leave your system on for 3-4 hours to get moisture 6-8 inches deep.
Raising mowing heights to a higher setting also encourages grasses to develop a stronger, deeper root system that outcompetes weeds, insects, and diseases. It also increases the competitiveness of your lawn by shading out germinating weed seedlings, an important management technique for prolific seed-producers such as dandelion. Raise the cutting height as high as possible and still maintain a pleasant appearance. Adult dandelion plants that are currently established will not be crowded out, but many of the germinating seeds that lead to perpetual weed problems will be shaded and crowded out, reducing your weed control chores this summer and every summer that follows.
Weeds are very good at what they do for a living, and in spite of your best efforts, some will survive and establish in your lawn. For the dandelions that are already present or establish in the future, treat with an herbicide containing 2,4-D. Be certain you read all the label instructions and follow them carefully. Wear long pants, a long-sleeved shirt, goggles, unlined rubber gloves and boots when applying the herbicide. Spot applications can reduce the amount of herbicides needed for the job.
Spot applications of glyphosate herbicides, such as Roundup, can be a least-toxic method of weed management in yard and garden. Remember though, glyphosate will kill any plant with which it comes in contact, including grasses and trees. Careful application is the key to using this herbicide without damage to desirable plants. It can be applied with a small sponge, or a rubber glove with a cotton glove worn over the top of the rubber glove and dipped directly into the glyphosate solution. A couple of drops on a dandelion plant is enough to do the trick. The newer herbicidal soaps, which are simply highly refined soap, are another least-toxic option, but will require more than one application because unlike 2,4-D and glyphosate, soaps will not move down into the dandelion root. Glufosinate-ammonium (e.g. Finale) is another least-toxic herbicide, a synthetic form of a product derived from naturally-occurring bacteria.
If you choose to dig dandelions, be sure to dig up the taproot to a depth of at least four to five inches to prevent regrowth, which occurs from the crown area, the junction of the plant top and the root.
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