Some facts about lawn care and maintenance
By Pamm Cooper - Turf Program Coordinator, University of Connecticut
Featured Article - posted Wed., Sep. 25, 2013
Most lawns are over-fertilized. With the exception of Kentucky bluegrass and perennial ryegrasses, which need from 3 to 4 pounds of nitrogen a year to maintain an acceptable quality, the tall and fine fescues only need 1 to 2 pounds of nitrogen per year
If clippings are returned to the lawn and not bagged, a full pound of nitrogen can be recovered and used by the grass plants, eliminating at least one nitrogen application each year.
An established lawn of cool season grasses like perennial rye, Kentucky bluegrass, and fescues should not be fertilized in the summer. Growth slows down as the soil heats up and the grass is in survival mode until soil temperatures cool down again. If the grass goes dormant during this time, it will not grow, and so it will not need fertilizer until conditions favorable to growth return.
If grubs have been a problem in the past, they often will be a problem in the same area again. Most chemical controls for grubs are ineffective when applied in the spring. The grubs are larger and physiologically different than they were in the fall, and will pupate by the time most applications are trans-located within the grass plants. The better time to apply systemic grub insecticides is in late June. This will ensure that the insecticide will be in the plant roots when grubs are newly hatched and are very susceptible to it. There is a new insecticide now available to home owners with the active ingredient Chlorantraniprole, which is extremely safe for birds, mammals, bees and beneficial insects, and has no signal word on the label. All grub control products need to be watered down to the root zone, either to be ingested by feeding grubs directly, or to be taken up by the plant where the insecticide will remain for three to four months in the roots.
A great percentage of crabgrass can be prevented from invading a lawn when the lawn is dense, healthy and mowed to a 3-inch height. Crabgrass is an annual grass that must start from seed from last year’s plants. A higher cut, dense lawn often shades crabgrass seedlings out so that they never can get established. If crabgrass has come in, and has developed seed heads, that is the time to bag the clippings. That way, the seeds will not drop into any open areas when the grass is mowed and become a potential problem the next spring. There is a new herbicide available to homeowners this year called Tenacity™ that is safe to apply for weed control at the time grass seed is put down. It is both a pre-emergent and a post-emergent herbicide that controls more than 40 weeds (including crabgrass) without harming lawn grasses. As always, read the label before applying any herbicide.
If moss has become a problem, there are a few things to consider. If shade is an issue, try to thin some of the tree canopy to get more light to the grass. Four hours of direct sun are the minimum grasses need to do well in. If the soil is suspected to be too acid, get a soil test done before adding limestone. All mosses are not the result of acid soils, or even shade conditions. A soil test will confirm pH problems and nutrient problems which need to be corrected. If all that happens is the moss is removed, and nothing else is done, the moss will return. The moss is not the problem. It is the result of some conditions that need to be changed to favor grass growth over moss growth like soil compaction, poor drainage or a shallow layer of topsoil.
Sandy soils benefit from the use of organic fertilizers. These will not leach easily in light soils, and they tend to build the soil up to a degree as they break down. Fast-release fertilizers, such as ammonium nitrate, tend to leach through lighter soils and may even end up in groundwater. They also are used up quickly – some in as little as three to four weeks. The flush of growth that is produced quickly, is just as quickly gone. Organic fertilizers may be slower to get started, but they last a lot longer – some can last up to three or four months, and promote even, slow growth without the spurts of growth and the crashes common to the fast-release types of nitrogen.
If perennial weeds are a problem, fall is a good time to apply herbicides, especially to ground ivy. For this weed, wait until the first frost and apply a selective systemic herbicide such as Trimec™, and then apply it again next spring when it is flowering. Many troublesome perennial broadleaf weeds need repeat applications at the correct time of year before they can be eliminated.
Late summer/early fall is the ideal time to repair areas of the lawn that are thinned or dead. Make sure to rake up any dead grass and loosen the soil surface a little before seeding so the new grass seedlings will be able to root. A thin layer of mature compost, top soil, or seed mulch can be put over the seed to help keep the seed moist. Remember to keep the seed from drying out to ensure optimum germination. Over-seeding can also be done with a slice-seeder. This machine makes shallow grooves in the soil and drops seed directly into to groves so it has good soil contact and is actually planted. Run an over-seeder at a half- rate of seed in two directions if the lawn is very thinned out. The seed must still be watered and kept moist.
As a final note, all lawns do not have equally good growing conditions. Soils vary from sandy to sandy loams to clay loams and have different abilities to hold moisture and nutrients. Some grasses, such as Kentucky bluegrasses, prefer a fertile well-drained soil and will not do well in light soils, especially in dry conditions without supplemental irrigation. Shade and sun conditions can vary on the same property, limiting a quality turf from developing if the wrong grasses are used. Get a soil test if there is any question about possible soil problems or nutrient availability.
If you have questions about lawns or any other gardening query, call the UConn Home & Garden Education Center (toll-free) at 877-486-6271, visit www.ladybug.uconn.edu, or get in touch with your local Cooperative Extension Center.