For most Nebraska lawn grasses – Kentucky bluegrass, perennial ryegrasses, and fine-leafed fescues – mow at a height of 3 - 3 1/2" inches, with the taller height recommended. This will usually be the highest or second highest setting on most mowers.
Tall mowing produces a deep root system that is important during periods of summer heat and drought. The larger leaf surface shades the soil and keeps it cooler. This shading effect makes lawn grasses more competitive with weeds that germinate from seed every year.
On the other hand, close mowing is detrimental to lawn grasses. It reduces the mass of roots beneath the grass plant and also the depth of the roots. Close mowing also produces less shading of the soil because there are fewer leaves on grass plants, resulting in higher soil temperatures and weaker lawn grass plants.
The general rule of thumb for mowing lawn grasses is to mow high, mow frequently, and allow the clippings to return to the lawn where they can decay and help recycle nutrients.
When to Mow:
Mowing frequency is based entirely on the growth rate of the grass. Try not to mow your lawn according to the calendar. But do mow often so that you remove no more than 30% of the leaf surface of the turf plants at one time. For example, if the mower is set at a 3-inch height, mow whenever grass reaches 4-4½ inches high.
Allowing grass to grow 6-7 inches high and then cutting it back to its normal mowing height of 3-31/2 inches results in plant shock which stops root growth. If root growth stops in the summer when temperatures are high and the soil is dry, grass will turn brown and become dormant almost immediately.
Mowing frequently benefits your lawn by producing short clippings. Short clippings quickly filter down to the soil surface when they decay and nutrients in the clippings are recycled.
Mow grass from spring to fall – as long as the grass continues to grow. There is no benefit to allowing grass to grow tall before the onset of winter. In fact, tall grass in the fall of the year is an open invitation for mouse invasion.
Grubs are simply the larval stage of the common June Beetle. Grubs feed on the roots of grasses, so lawns will show wilting and browning of irregular shaped areas. Certainly there could be many reasons for lawns browning, especially in late summer when most grub damage occurs. Always check the root zone of affected areas for the c-shaped grubs. Carefully pull back the sod in suspect areas, in particular the marginal areas where brown grass meets green grass, and look for the grubs. Usually a population of about 10 or more grubs per square foot will lead to browning of the lawn.
Annual broadleaf weeds, can be controlled with an application of preemergence herbicide in the spring. A second application at a reduced rate may be necessary for season-long control. Perennial broadleaf weeds can be controlled with an application of a broadleaf herbicide in the fall (late September to early November in Iowa).
In the fall, perennial broadleaf weeds are transporting carbohydrates from their foliage to their roots in preparation for winter. Broadleaf herbicides applied in fall will be absorbed by the broadleaf weed’s foliage and transported to the roots along with the carbohydrates, resulting in the destruction of
broadleaf weeds. The most effective broadleaf herbicide products contain a mixture of two or three herbicides as no single compound will control all broadleaf weeds.
A single application of a broadleaf herbicide effectively kills many broadleaf weeds. Difficult-to-control weeds, such as violets, ground ivy and even dandelions may require two or more applications.