Master Gardener^sm Column for the Week of May 16, 2005
Charlie Spencer
Brunswick County Extension Master Gardener^sm Volunteer

To continue with the do’s and don’ts of lawn care… mowing is the topic for this article. Proper mowing practices can determine the success or failure of a lawn. Improper mowing can ruin a lawn in a hurry. Mowing correctly, however, can help you overcome many lawn problems. The two most important aspects of proper mowing are cutting height and frequency.

How high and how often you cut your grass is determined by the type of grass you have. A grass that naturally has a more horizontal growth habit can be mowed shorter than a naturally upright type. Grasses with narrow blades can generally be mowed shorter than grasses with wider blades. Bermudagrass, because of its numerous narrow leaf blades and low growth habit, can be mowed at a low height. On the other hand, bahiagrass should be mowed higher because of its upright growth habit – that is, if you grow bahia!

Each time your grass is mowed, it endures a physiological stress. This is especially true if too much leaf blade is removed. Lawngrasses make their own food through a process called photosynthesis. To absorb needed sunlight for this process, a good healthy leaf surface is required. Mowing below the recommended height decreases the total leaf area and the plant’s ability to produce enough food to meet its needs. One of the leading causes of dead areas in lawns is mowing too low.

Mowing also directly influences the depth of grass roots--the higher the mowing height, the deeper the roots. A deep root system is vital to a healthy lawn. The advantages of a deep root system are greater tolerances to drought, insects, disease, temperature stress, and traffic.

The recommended mowing height for centipedegrass is between 1 1/2 to 2 inches. St. Augustinegrass and bahiagrass should be mowed between 3-4 inches. However, the new semi-dwarf varieties of St. Augustinegrass can be mowed lower with a recommended height of approximately 2˝ inches.

During stressful conditions such as heat, drought, or extensive shade raise your mowing height to the upper limit of the recommended range or even slightly higher.

How often you cut your grass is determined by the growth rate of the grass. In other words, the decision to mow should be based on the amount of growth since the last cutting rather than the number of days that have elapsed.

Mow often enough so that no more than one-third of the blade height is removed per mowing. It is important to always leave as much leaf surface as possible for photosynthesis to provide food for regrowth. For example, if your St. Augustinegrass lawn is regularly mowed to a height of three inches, the grass should be cut when it reaches 4-4 1/2 inches.

One of the most damaging mowing practices is a sudden reduction in mowing height. If your lawn has been allowed to get too tall you should gradually lower its height with several mowings.

Should you bag or leave your clippings? On most lawns, it is not necessary to bag your grass clippings. Leaving the grass blades helps recycle nutrients to the soil. If your lawn is not overfertilized and is mowed frequently enough, the clippings will be beneficial. Contrary to popular belief, research has shown that clippings are usually quickly decomposed by soil microorganisms and do not contribute to thatch. Problems can occur if piles of clippings are left on the grass surface. If this happens, spread the clippings out by raking lightly or using a leaf blower to distribute them.

Tip of the Week: If you do not have a lawn maintenance calendar for your type of grass, call the Cooperative Extension Service for your free copy. Source: Theresa Friday, Extension agent with Florida’s Santa Rosa County

Send your gardening questions or comments to: Brunswick County Master Gardener Column, P.O. Box 109, Bolivia, NC 28422, or call (910) 253-2610. Enclose a self-addressed stamped envelope if requesting information or a reply. Answers may be printed in this column.

For further information or assistance, please e-mail:
Charlie Spencer, Brunswick County Extension Master Gardener^smVolunteer

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Date Created 5/13/2005