If Weeds Are Taking Over Lawn, You Need To Defend Your Turf

September 15, 1991

Should you consider lawn renovation this fall?

Done well, it may be a solution. Done poorly, it is a time-consuming task to achieve what you have now at no cost -- namely, a thin, weedy lawn.

Successful renovation can be achieved by the average weekend gardener. No mystery or magic is necessary, but sweat and hard work are required.

Turf renovation involves the elimination of competing weed species and the reseeding of a desirable turf grass cultivar. Depending on the lawn's condition, renovation may be necessary on the entire lawn or on only a small section of the turf.

Review the existing cultural and site conditions that may have caused the need for renovation. Poor drainage, excessive shade, poor fertility, disease, weeds, improper pH, compaction and high insect populations may need correction before you begin renovation. A newly-seeded turf may succumb tothese pre-existing problems.

The ideal time for lawn renovation is the fall, when grass seed has a longer establishment period and will be able to germinate in cooler, moister weather without much competition from weed seedlings.

Whether total renovation or spot renovation is contemplated, the basic steps are the same:

* The first step is to kill all the vegetation in the area to be renovated. Both perennial weeds and the existing turf grass should be targeted for removal.

Herbicides are the easiest method of destroying the existing vegetation. Apply a systemic contact herbicide. Allow the area to be treated to grow without mowing for a few weeks before renovation to provide more leaf surface for good herbicide contact. Be cautious not to spray or to allow the spray to drift onto any other desirable plant species.

Herbicide may be slow-acting and will take about two weeks to kill the turf area. Wait for the sprayed area to turn completely brown before proceeding with renovation. Mow the area to a height of 1/2 inch once the old lawn is completely brown.

* Thatch can be a problem if it is thicker than 1/2 inch. Dethatching with a rake is great for small areas. For larger areas, mechanical dethatchers are back-savers.

Gasoline-powered verticutters or dethatching machines may be rented at some hardware stores. In design, they are similarto a lawn mower with vertical blades, engineered to cut perpendicular through the turf layer. They should be adjusted to cut through the thatch layer and into the underlying soil to a depth of 1/4 to 1/2 inch. The verticutter will remove both the thatch layer and will tillthe soil to form a seed bed for new turf. Several passes will be necessary for complete thatch removal.

* You should remove all the thatch and clippings generated by these operations. However, do not remove the loose soil.

* Apply lime and fertilizer according to your soil test recommendations. University of Maryland soil test kits can be obtained from the county extension office or the Home and Garden Information Center (1-800-342-2507). If no soil test results are available, a general recommendation would be to use 50 pounds of lime and 30 to 40 pounds of 5-10-10 fertilizer per 1,000 square feet on heavier soil.

* To prepare the seedbed for seeding, rake the area level and select a turf grass cultivar. In general, the turn-type tall fescues are the best choices for home lawns in Maryland. Excellent reference guides for cultivar selection and seeding rates are available from your local county extension agent.

As a seeding suggestion, apply half the seed in one direction and apply the second half perpendicular to the original seeding direction.

Lightly rake the area afterseeding to work the seed into the soil. If you can rent a lawn roller, roll the area to compress the soil lightly and further ensure goodcontact between the seed and soil. Under dry conditions, mulching the area with weed-free straw at the rate of 75 to 100 pounds per 1,000square feet will reduce moisture loss and further insure success in lawn renovation.

* After planting, regular and frequent watering speeds seed germination. Tall fescue and Kentucky blue grass species germinate slowly compared to annual rye. Newly-germinated seed has a limited root zone and will need watering to wet the roots.

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