As spring arrives, the landscape comes to life, including the lawn.

By using the best management practices of proper mowing and applying fertilizer in the fall, the lawn is enhanced and the amount of fertilizer may be reduced to protect the environment.

Properly mowing the lawn helps to improve its quality. An important mowing practice is to sharpen the mower blade at the beginning of the season and then several times during the season, possibly four to six times per year. A sharp mower blade makes mowing easier, reduces wear on the mower, and results in a better looking and healthier lawn. A dull mower blade tears the leaf instead of making a clean, sharp cut. A torn leaf blade is more susceptible to invasion by a disease.

The recommended mowing height for tall fescue is 2 to 3 inches, and for Kentucky bluegrass the height is 2 to 2.5 inches. Mowing at the best height for the grass encourages a deeper root system, which will help protect your lawn against drought and weeds.

Following recommendations for mowing height and frequency will make your lawn care responsibilities easier and result in a more attractive yard.

If your mower has a fixed, all-year height, set it at 2.5 inches. However, if you can easily vary the height, set it at 1.5 to 2 inches for the first several times you mow.

The shorter mowing height will help remove a lot of the winter-burned, brown leaves. Exposing more dark green growth will transform your lawn into the most uniform, attractive one in the neighborhood. Move the height up to 2.5 inches after you mow the grass several times.

When summer arrives, protect your grass from summer heat and drought injury by raising the mower height to 3 or 3.5 inches. However, remember that extra high grass, especially tall fescue, tends to fall over and mat down during hot summer weather causing increased summer disease problems.

Another tip is to mow often so that only one-third of the grass blade is removed at any one time. During the spring, the lawn may need to be mowed more than once a week.

Mowing off more than 50 percent of the leaves at one time causes scalping, resulting in increased weed competition and in the death of some grass plants during the hot summer.

While mowing the lawn, what should be done with the grass clippings? The answer is, leave the clippings on the lawn. Leaving grass clippings on the lawn saves time, money, and energy, since you don’t have to stop and empty the bagger or buy trash bags.

Clippings also add free fertilizer to the lawn, possibly as much as 25 percent of the lawn’s annual nutrient needs. Remember, grass clippings are not accepted in the garbage.

Grass clippings do not increase thatch. Clippings contain 75 to 85 percent water and decompose quickly. Thatch is a tight, intermingled organic layer of dead and living shoots, stems, and roots that develops between the green leaves and soil surface.

A little thatch is good, since it helps moderate temperature extremes at the soil surface and provides a cushion effect on the surface.

Grass clippings will decompose quicker if the clippings are short. While a mulching mower or blade is not necessary, it does cut or shred the leaves into small fragments.

Collecting grass clippings may be necessary when the grass is tall and normal mowing tends to windrow the clippings, causing smothering of the grass underneath.

The collected clippings can be used as a mulch around ornamentals and between garden rows to a depth of 1 inch. Do not mulch with clippings from lawns that were treated with a herbicide to control weeds.

When thinking about fertilizing the lawn, nitrogen applied in mid-spring causes more problems than it solves. It results in excessive grass growth that may make it difficult for you to mow often enough to remove the recommended one-third to one-half of leaf material at each mowing.

It decreases spring root growth and summer drought tolerance as well as increases weed and disease problems.

The best time to apply nitrogen is in the fall. Fall fertilization helps the lawn develop a deep root system and become very dense to crowd out spring weeds.

For more information about best management practices for the lawn, contact the Daviess County Cooperative Extension Service at 270-685-8480.

Annette’s Tips

Since crabgrass begins to germinate when the soil temperature is between 57 and 64 degrees at the 1 inch soil level, the time is closer to apply a per-emergence herbicide. The UK Ag Weather website has a map with soil temperature from across the state to use as a resource at or Try to use a pre-emergence crabgrass preventer without nitrogen. Read and follow label directions. Only herbicides specific for crabgrass prevention can be used when seeding a new lawn without damaging the new seedlings. Do not apply the crabgrass preventer on snow or before a heavy rain because the herbicide may be washed away and carried off target.

Mid-March to mid-April is a good time to treat valuable ash trees in your landscape with a DBH of 20 inches to prevent damage by the emerald ash borer. The treatment involves a soil drench containing the active ingredient imidacloprid. This borer has not been found in Daviess County yet, but has been found in traps across the river near western Daviess County.

Annette Meyer Heisdorffer is the Daviess County extension agent for horticulture. Her column runs weekly on the Home & Garden page in Lifestyle. Email her at

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