Karen Cambre, Sharpe, Kenneth W.
September is the start to changing out annual beds and sprucing up the landscape. We spend a lot of time thinking about our plant selections and how to make our outside living spaces more attractive.
In most yards your area is mostly covered in lawn grasses. It too requires a little maintenance. It is relatively easy to change out a few shrubs or beds but the lawn is another matter.
Plants, including grass, have a much easier time warding off pests, diseases and even competing with weeds if they are healthy and taking in the proper nutrients. September marks the start of the transitional period where grasses are reacting to shorter days and cooler nights. Warm season grasses will pull back their growth and start storing nutrients for the winter.
We will still have warm days and we want to take advantage of those warm days to feed the grasses for winter and still get good uptake of the nutrients. Many people will refer to this feeding as winterizing the lawn.
We are too late in the year to use fertilizers with nitrogen. Nitrogen will make grasses tender and vulnerable to cold damage. So, while we do want to winterize the lawn, I must caution you that some of the commercial fertilizers on the market that use the term “winterizer” are high in nitrogen and not suited for southern warm season grasses such as St. Augustine, centipede, carpet, Bermuda or zoysia.
The only nutrient needed for winterizing your lawn is potassium. The most readily available source of potassium is the fertilizer, Muriate of Potash, which has a fertilizer analysis of 0-0-60. You can apply muriate of potash at a rate of 2 pounds per 1000ft² of lawn area. Apply it to a dry lawn and then water it in.
It is noteworthy that in the granular fertilizer business we have a saying that “a pint is a pound the whole world round”. This means that a pint of granular fertilizer weighs approximately one pound, so you can safely assume that a quart weighs about two pounds.
If you choose to use a commercially prepared “winterizer” fertilizer, select one with no nitrogen. All fertilizer packages have three numbers on the bag which will represent the percentage of nitrogen,percentage of phosphorous (P2O5) and percentage of potassium (K2O) in that order. A fertilizer that has an analysis of 5-10-15 would have 5% nitrogen, 10% phosphorous (P2O5) and 15% potassium (K2O).
We can get very dry this time of year so pay attention to watering. The grass will continue to grow until night time temperatures start to dip toward the 50’s. You need to keep up with watering and cutting so the grass is healthy going into winter.
As the temperatures start to dip and day time temperatures stay below 80º F, brown patch will start to appear, especially in wet weather. Brown patch is a fungal disease that is common in our warm season grasses and can be very active in the fall and on into the winter especially in a mild winter when the grass is not dormant. If you see circular brown to orange spots in the lawn, apply a fungicide treatment to stop the spread. Make three applications 10 days apart with a fungicide containing propiconazole, thiophanate, triadimefon or myclobutanil.
A small investment of time and management now will go a long way toward you starting off next spring with a nice green healthy lawn that will accent your home and landscaping.