What to do this week –By Mark Govan, Host “Florida Gardening”
This week I have decided to go over some specific turf problems many of you have been asking about. How to cure hardpan soils, when I need core aeration, and should I verti-cut or dethatch my lawn, seem to be questions I receive regularly. All of these problems can be easy to overcome if you have the right answers. Although these questions only come up every so often, I would like to put down on paper what you need to know to give you, the homeowner, a way to handle these landscape issues. I am sure that with the information you glean from this article, you will be able to make an informed decision on which path you need to follow to correct these problems when you find them in your landscape.
Hardpan or compacted soils are areas within your landscape where water seems to stand following a rain or irrigation cycle. Some of you may notice areas where you had grass growing but over time these areas have turned into a path rather than a lush lawn. In some instances, you may not even know you have a hardpan unless you try to plant a new tree or shrub in the landscape. If you dig a hole to plant a shrub or tree, and you notice a dark hard layer of soil anywhere from six to twelve inches below the top soil, then you may have hardpan. Depending on the depth you find this hardpan soil, there may be limited ways for you to correct this problem short of digging the entire area up and breaking up the compacted soil. Digging out the whole area could be more than you bargained for, but if you have hardpan, then this is the only way to relieve the problem. However, if your soil is merely compacted, then have a few options available to you.
In some cases, you may inadvertently compact soil through the normal use of a path or a runway your dog follows repeatedly. Even parking a vehicle on the lawn for a short time can cause compaction over time. Although hardpan soils and compacted soils are different, the complications which arise from these types of soils are basically the same. Once the soil is compacted, the distribution of water, oxygen, and the elements needed for proper turf or plant growth are restricted. This causes the eventual stunted growth or rotting of your plants root system and ultimate death of the plant or sod.
I have found that working with Mother Nature to convert these areas to a hard-scape may be easier than trying to amend the soil. You can do this by placing stepping stones in a path you normally follow or even laying down a border on either side of the path with some pressure-treated wood and filling in the center with a mulch of some kind. Hard- scaping these areas may be the least labor intensive way to live with these paths but sometimes, you have no choice but to correct the problem. If you need to correct these areas, then I have a couple of easy suggestions of how to manage them.
An old-fashioned way to correct compacted soils is to use an old pitchfork and drive the tines into the ground every three inches, down the entire path. You only need to penetrate the ground to a depth of eight inches. If the path you want to save is very long, then you will have to spend the time necessary to alleviate the problem. The holes you are pushing into the ground will allow air and nutrients to penetrate the hardpan and allow better water movement through the soil. This can help to save the existing plant material in the area you are working in.
Please remember that this is not a quick fix. Over time, the grass or groundcover you have will respond to the additional nutrition and oxygen given to their root systems. A light application of fertilizer will also help your plants respond. I know this method sounds labor intensive, but if you have a small area, then this is a good option for you. If you have a large area, then you will need to use a different method called core-aeration.
Core-Aeration works on the same principle of the pitchfork method I explained above but is more effective and requires less physical labor on your part. You can rent a core-aerator machine from the local rent-it shops, or you can hire a company that specializes in core-aeration to come to your home and provide this service for you. Core-aerators are power driven machines that consist of rows of tubes approximately three to six inches long and one-half to three-quarters of an inch wide. These tubes are power driven into the ground at a pre-determined depth, and they physically remove a small core of soil from the ground. After the machine has finished going over your yard, the cores are usually removed by raking them up and disposing of them.
The small holes left behind leave tiny pockets in the ground that air, water, and nutrients can be absorbed by your plants to help them recover. This treatment should only be performed every few years depending on the activity you or your pet have in the landscape and the level of compaction of your soil. I have seen vast improvements in the color and density of turf grass in a few short months following this service.
Another problem you should be aware of in turf grass is thatch buildup. For those of us who grew up in the north, the yearly task of de-thatching the lawn in the spring was a backbreaking task. I am sure you can remember pulling out the old thatching rake, with the heavy sharp cutters, and pulling it through the grass back and forth to remove the withered winter grass. Then you had to bag up the dead grass and throw it away. This process helped our northern lawns break dormancy and fill in better. Well, in Florida, we do not grow the type of grasses we had up north, and most of us deal with St. Augustine grass. Depending on varieties of St. Augustine you have planted and the way you fertilize your lawn, you may notice that you get that sinking feeling every time you decide to take a stroll over the lawn. This is called thatch buildup.
I have seen some lawns where the thatch has built up so much that in order to work on your sprinklers, you would have to reach down into a hole through the thatch just to find the sprinkler let alone repair the broken head. In fact, many times we find the sprinkler is fine. The problem is the head which used to pop up and water the lawn cannot make it out of the layers of thatch, which have built up. What Happened? Well, there are a couple of reasons this has occurred.
Homeowners, who feed their lawns regularly with high nitrogen fertilizers such as a 27-3-3, have done a disservice to their lawn. Nitrogen, represented by the 27 on the bag of fertilizer, increases the top growth of the lawn. On a St. Augustine lawn, nitrogen makes the lawn produce new runners on top of the soil surface. These runners pile up on one another and over a period of time create the thatch or sponginess you feel when you walk across the lawn. Another reason we get this thatch buildup is when we plant the wrong cultivar of St. Augustine, or we mix different cultivars of this grass on the same property.
Planting a shade-tolerant variety of St. Augustine grass in the full sun can cause a major thatch buildup. I cannot tell you how many times I have seen homeowners plant St. Augustine Seville, Delmar, Captiva or Bitter Blue in the full sun. These cultivars of St. Augustine grass should be planted in semi-shade. Cultivars of St. Augustine grass designated for full sun are Floratam, Floralawn, or Classic. When you plant a shade-tolerant cultivar of St. Augustine grass in the full sun you can get a massive thatch buildup. Many of the shade-tolerant varieties of St. Augustine are dwarf or semi-dwarf varieties meaning they do not grow as fast or tall as the sun-loving varieties. Unfortunately, when these shady varieties are grown in the full sun, they tend to pile up the thatch and are more susceptible to disease and insects.
Once you have a thatch buildup problem in your lawn, you have only a few choices to get rid of the problem. You can have your lawn verti-cut by a professional, you can change the cultivar of St. Augustine you are currently growing (very expensive), or you can change your habits of over fertilizing with nitrogen.
I cannot stress this point hard enough; verti-cutting should only be performed by a professional. When you select a company to perform this service for you make sure you call their references and talk to them before allowing this service to be done. Do not have your lawn verti-cut during the summer or when temperatures are over eighty five degrees. The best time of the year to have this service performed is in the winter months when the grass is dormant. Remember, verti-cutting is very hard on your lawn and if done improperly, you can lose your lawn. You will be amazed at the amount of thatch that is removed from your lawn. An average five thousand square foot lawn will have several truckloads of thatch removed. Once completed, your lawn will look similar to a lawn that has just been plugged. Normal recovery time for a dethatched lawn is several months.
I should make a note that those of you growing zoysia grass would probably benefit from the purchase and use of a de-thatching rake in the spring of each year. As more and more homeowner’s plant zoysia grass, the maintenance regiments we are used to with St. Augustine grass must change. I will have more information on maintaining zoysia grass in the future.
Well, I hope I have cleared up a few problems many of you have been thinking of and just did not know what type of question to ask. All the problems listed above can be time-consuming to rectify and labor-intensive. Try the easy ways I listed above and work with Mother Nature when possible. When you find you cannot do the work yourself, call in the professional but check their references. Good Luck working in the landscape and remember, this is supposed to be fun! Completing a little work each day can add up to a major accomplishment. Remember, without plants, we would not be here! Happy Gardening!