I have had several readers contact me to say that their lawn has looked great all winter but now it is turning yellow and declining. Some have fertilized, hoping to restore the lushness and green color.
The problem is that their lush, green winter lawn was from rescue grass, a winter weed grass. Annual blue grass or rye grass could also cause this symptom. All of the winter annual grasses are declining now because the weather has warmed up. As a last hurrah, the weeds are attempting to produce seed. Rescue grass seed heads look like oats.
It won’t matter what you do in terms of irrigation or fertilization, the winter weeds are at the end of their life. There is also no advantage to applying a contact herbicide. Contact herbicides work best on young weeds during the early part of their growth cycle.
Mark your calendar for next year on or about Sept. 1. Apply a pre-emergent herbicide, such as Amaze or XL, at that time. It will prevent annual weeds, such as thistle, dandelion, beggar’s lice, henbit, chickweed, rescue grass and annual blue grass from invading the lawn.
Of course, if the lush green winter lawn provided by the weeds looked good, you may want to let them return.
The warm weather ends the life cycle of the winter weeds and marks the time when the permanent lawn grasses begin their growth period. If you look closely in the lawn, you will probably find St. Augustine and Bermuda grass emerging.
To assist lawn growth, apply the spring fertilizer now. Use a slow-release lawn fertilizer, such as 19-5-9. The label on the bag will tell you how much to apply.
If you have an irrigation system, you do not need to be watering yet, but call in your irrigation contractor for an inspection to find and repair leaks and malfunctioning sprinkler heads. Consider converting any sprinkler zones that water flowers, vegetables, shrubs or trees to drip irrigation. Drip irrigation uses less water and is better for the plants because the water is applied at the roots, not over the foliage.
Mow St Augustine grass at 3.5 inches, Bermuda grass at 1.5 inches and Zoysia grass at 2 inches for best performance.
Visit the San Antonio Water System website and check out the rebates offered for conversions from sprinkler irrigation.
Dr. Calvin Finch is Director of Water Conservation and Technology at the Texas A&M University. You can ask him questions about about horticulture, water conservation and the environment by sending him an email Calvin.firstname.lastname@example.org.
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