Lawn grasses are susceptible to all sorts of natural diseases, mold and fungal infections, and insect and pest interference. It is the responsibility of the lawn owner to protect lawn grasses from these ailments. But lawns are also susceptible to damage due to poor lawn care maintenance. Scalping, a type of over-aggressive lawn mowing, belongs to the latter category. By understanding the causes of scalping and what to do to save a scalped lawn, you can avoid the self-inflicted problems associated with lawn scalping.
Lawn scalping occurs when more than one-third of the canopy layer of the grass is removed during mowing. This close mowing exposes the stem tissue of the blades of grass. To compensate for the damage, the grass has to produce new shoots in order to collect sunlight. To produce the shoots, the grass has to dip into food reserves stored in its crows and roots, leaving the grass nutrient-deprived and destabilized.
Scalping can have potentially serious deleterious effects on your lawn grass. Scalped grass is thin and structurally weak, leaving it more prone to damage from invasive weeds. Scalping also causes numerous cosmetic issues for your grass; scalped areas turn brown and yellow. The damage caused by scalping varies somewhat depending on what species of grass you planted in your lawn. Cool season grasses like ryegrass, tall fescue and Kentucky bluegrass are more sensitive to scalping damage than are other varieties such as Bermuda grass.
If your lawn has suffered damage due to scalping, first assess the degree of damage that the lawn has suffered. Bermuda grass will often grow back healthily over time. Ryegrasses, fescues, bluegrass and other "bunch" grasses and cool-season grasses are capable of growing back on their own as well, but will often need to be resodded or reseeded if severely damaged. In either case, the most effective way of preventing future scalping damage is to only mow your grass to the height recommended for that specific grass species.
In Bermuda grass, the symptoms of scalping damage closely mirror those of a condition called iron chlorosis, particularly if the grass is not mowed frequently enough. To arrive at a conclusive diagnosis, feed your lawn an iron supplement, and adopt a mowing schedule and height that is recommended for your grass. If these do not return the grass to normal health, the grass may have been scalped.