Since it has been raining a lot now, I have been clipping my lawn down to the lowest height possible, so that I don’t have to mow so often. I am sure that it won’t dry up. But what can I do to thicken it up? I feed it a lot, but still there is too much bare dirt in the lawn area. And the weeds are getting worse. Will mowing it more often at the lowest setting help? I have Saint Augustine in the front and Bahia in the back yard.
The first thing you must do is to raise your mowing height for the entire lawn. While Bahia grass needs to be cut at 3 to 4″, Saint Augustine needs to be 3.5 to 4″. You are doing what we call scalping. It is the primary cause of turf injury, and damage can occur regardless of how much rain we get. Mowing it more often at this height can not possibly help either. The reduced amount of leaf blade area causes stress because the lawn can no longer produce much energy from the sunlight. In this weakened condition, the lawn now has an increased need for fertilizer, weed killers, pesticides, and fungicides. This can result in thin areas and even bare spots, and can suppress root growth. Weeds can now find more spaces to sprout. After getting the weeds out, and increasing your mowing height, you can go ahead and add sod to the bare areas.
But I don’t want to mow that often. I’ve heard that at least Bahia grass will be OK being mowed low.
Since Bahia grass has a tall upright habit, it needs to be at the recommended height as well. Even at a low height, your lawn may look pretty unkempt after a week or two. The height has little to do with how often the lawn appears to need mowing. It is more a factor of time, rather than height. If anything, the lower height increases the need for fertilizer, which actually makes the lawn grow faster. To make things worse, many weeds can out-compete lawns at such a low height. A taller lawn can keep light from the surface, which can help to suppress the weeds.
Saint Augustine, with its wide leaf blades, also has a need for higher mowing. Only the dwarf varieties can be cut a little lower.
Are there any other mowing tips? Yes, the mower blades need to stay sharp, in order to keep from tearing the leaf blades and inviting fungal diseases. Change mowing directions and patterns frequently to make sure the lawn is mowed evenly. Do not mow when the lawn is wet, or when it is in need of water. Clippings should be left on the lawn, but not in clumps. A mulching mower may help to prevent clumping. Raking can also disperse them if necessary. Be sure not to leave grass clippings in the road, where they will end up in storm drains. If they don’t clog up the drainage system first, they can create algal bloom and fish kills in drainage ponds, where they start to decay. The clippings have nutrients in them which will be put to better use on your lawn, where they can reduce the amount of fertilization needed. And finally, make sure that any automatic irrigation systems are not coming on right now.
The recommended length of time between mowing events is generally 7 to 14 days, at the proper height. No more than one third of the length should be taken off at a time. When you consider this, regularly taking a lawn down to one inch after being allowed to grow to 5″ is really not a good idea. And regularly keeping it at 1 or 2 inches could be even worse.
Reducing the amount of lawn you have could also be an option. Clumps of small trees and shrubs would certainly be something else to consider.
By: Sandy Switek, Master Gardener & Eva Pabon, Master Gardener Coordinator