Lawn Care Q&A
Master gardener Paul James addresses commonly asked questions concerning lawn care, including the control of Bermuda grass, the benefits of mycorrhizae and the debate about seed vs. sod.
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Master gardener Paul James answers questions concerning lawn care.
Q: How do I keep Bermuda grass out of my flower beds?
A: Bermuda grass is a tough turf that thrives in warm, sunny climates throughout much of the United States and spreads quickly to create an attractive lawn. Its ability to spread also makes it potentially invasive.
Bermuda grass spreads via runners above and below ground. The only way to prevent runners from getting into flower beds is to construct a mechanical border. Install stone, steel or plastic edging along the edge of the flower beds. Just make sure to install the edging three inches below ground or the runners will creep under it. They'll also run up and over the edging, so be prepared to run a string trimmer along the edging every week or so. If the runners do find their way into garden beds, pull them out, making sure to get all the little pieces of root, or use horticultural-grade vinegar as an herbicide to kill it outright.
Q: How do I control weeds without using any chemicals?
A: Assuming you're willing to tolerate some weeds in the lawn, it's not as hard as you might think. First, set your mower to the highest setting. Tall turf shades the soil and prevents sunlight from reaching weed seeds that are lying in wait to germinate. In fact, in a study at the University of Maryland, crabgrass and other weeds accounted for 53 percent of the overall lawn cover in test plots mowed to a height of 1-1/2 inches, but in plots mowed at a height of 2-1/2 inches, the weed population was a mere eight percent.
Proper fertilization can provide similar results because a healthy turf will ultimately choke out all but the most persistent weeds, and those you can eliminate by hand pulling. Fertilize with an organic product twice a year – once in the spring and again in the fall.
Mow before weeds flower and have a chance to set seed. Provide adequate moisture for the grass – not too much, not too little. Aerate the lawn at least once every two to three years so the soil doesn't get too compacted.
Q: What's the best way to repair tire ruts in the lawn?
A: Use a garden fork to loosen the soil in the damaged area. Then apply a composted product or topsoil to fill the area up to the grade level, tamping it slightly as you go and leveling it with a rake.
At this point, there are a couple of options. If the turf in question has a tendency to spread — as do Bermuda, buffalo, St. Augustine or centipede grass — then allow it to grow and fill in the area on its own. But if the surrounding turf doesn't spread like fescue, then you'll have to reseed. To do so, sprinkle the grass seed on the bare spot, tamp it lightly to achieve good soil-to-seed contact and water. Within about two weeks, you won't even know the ruts were ever there.
Q: I'm putting in a new lawn. Should I use seed or sod?
A: Although it may be a matter of personal preference, the answer comes down to one consideration — cost. How much do you have to invest in a new lawn? Seed is relatively cheap, and it's easy to sow. However, it does take at least a week or two to germinate, and depending on the type of turf you're planning on growing, timing is critical.
Cool-season grasses, such as fescue, rye and bluegrass, are best sown in early spring or fall because they don't germinate well during the hot summer months. On the flipside, warm-season grasses such as Bermuda, buffalo, St. Augustine, and centipede are best suited for sowing in early summer when temperatures are warm.
Sod is actually more forgiving. Regardless of the type of turf you're using, sod can be applied pretty much anytime between the last hard freeze in spring and a few weeks before the first hard freeze in fall. Sod also provides instant gratification, but it's also more expensive.
Q: I recently saw a grass seed that contains something called mycorrhizae. What is that and is it a good thing?
A: Mycorrhizae is a fungus, but it's a beneficial one. So yes, it's a good thing. This fungus exists naturally in soils, and it improves the ability of plant roots to take up nutrients in the soil. However, it rarely occurs in sufficient quantities to provide the maximum effect, which is why you can now buy mycorrhizae fungus and inoculate your entire garden. It's even being included in many natural fertilizer products.
The seed mentioned above is actually coated with three different strains of mycorrhizae, and they help create a sort of partnership between the soil and the grass roots. That partnership enhances the lawn's vigor, reduces its water requirement by as much as 30 percent and makes it more tolerant of environmental extremes.
Q: How do I get rid of the yellow spots in the lawn where my dog has peed?
A: Training your dog to go in a specific area will, at least, confine the yellow spots to one location in your yard. But that's easier said than done. Ultimately, the best way to prevent the yellow spots from forming is to water the area to dilute the urine. Water the area up to eight hours after the fact.
Q: What is top dressing for the lawn?
A: Top dressing is a mixture of composted organic matter that can be applied to the top of the lawn. Paul prefers to use a natural product that comes in 50-pound bags. The nutrient analysis of this top dressing is 7-2-2, meaning it contains 7 percent nitrogen and 2 percent each of phosphorous and potassium.
The 7-2-2 formulation of top dressing can also be applied using a broadcast spreader. Some products sold as top dressings are too coarse to go into a spreader, and therefore must be applied with a shovel, which can be a pain. When applied at least twice a year – once in the spring and again in the fall – top dressings provide both organic matter and nutrients. All it takes is 10 to 15 pounds per 1000 square feet. If you apply a top dressing twice a year and mow with a mulching mower, forget about using turf fertilizers. The nutrients in the top dressing and the grass clippings are all your turf needs to grow.