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Most lawns grown in Houston are St. Augustine grass. It is a course and not "soft to walk on barefoot" grass. It is much different than the grasses grown up north. St. Augustine loves our heat and humidity, spreads quickly and competes well with weeds. It tolerates shade better than all the other grasses we can grow here. It is a grass, though, that requires a lot of water, frequent mowing and can attract damaging insects and diseases.
Fertilization
The average homeowner fertilizes twice per year. These lawns will not be as thick and lush as yards that apply fertilizer 3-5 times . Grass grows very fast in the heat and requires a lot of nitrogen to stay dark green. This is not to say that a lawn that is fertilized twice a year can not be a healthy lawn. It can! It will just not be as thick and green. If your expectations are lush and deep green then you will have to apply fertilizer up to 5 times, 8 weeks apart, starting in March and finishing in November.
There are many great fertilizers to chose from. Your best bet is to find one made in Texas. They would be the best for Southern lawns. A slow release 3-1-2 ratio or a 4-1-2 ratio should be applied for the first 4 treatments. Use a Winterizer for the last treatment in November.
Do not use Weed and Feeds except in cases where most of your yard is full of broad-leaved weeds. Never use them in hot temperatures. Apply them from February thru mid April only and in November if needed. Read the directions carefully!
Organic lawn foods are becoming more popular and with good reason. They keep your soil healthier than synthetic fertilizers, reduce water needs, reduce disease pressure and are better for the environment. You can apply organic fertilizers any time of the year.
Watering
Watering should be simple but it is not necessarily understood by many homeowners. There are quite a few variables that have to be accounted for proper watering. Temperature, light conditions, soil type, humidity, wind and type of sprinkler head would all play a factor in how often and how much water to apply. You will hear that your grass needs 1-2 inches of water per week. That is not easy to keep track of every week!
How about watering thoroughly.... but as infrequently as possible. That is a simple concept. Here is how you do that.
Water thoroughly. 20 minutes for mist heads or 40 minutes for rotary heads per station. Count how many days it takes for your grass to show water stress (leaves fold). If that takes 4 days then set your sprinklers to water every three days. That way you know the soil is drying out before you water again. When the seasons change repeat the process and adjust accordingly.
In the winter turn your sprinkler system off automatic watering. Use the manual control to turn it on during dry times. Grass that is dormant does not require very much water. If, however, a hard freeze is forecast be sure to water thoroughly.
Try to water in the morning if possible. Watering grass in the evening promotes diseases like brown patch and gray leaf spot.
Light
St. Augustine grass always prefers full sun but can tolerate lower light conditions fairly well. If you have lost grass due to shade you will have to provide substantially more light or try one of the new varieties of St. Augustine that does better in low light conditions. At this time, Amerishade is the best variety for those heavily shaded areas.
Grass in shade requires less fertilizer than in full sun so be sure to make the applications at half the normal rate in those areas.
Mowing, Dethatching and Aeration
Many Houstonian's do not do their own mowing. They do not seem to have complete control over this aspect of their lawns care. Your yard is likely to be mowed at the same height, sharpness of blade and pattern as the customer before you. Hopefully your maintenance company is aware of the proper settings and techniques.
A sharp mower blade is very important. Mowing with a dull blade is actually stressful to the grass because it tears the blades instead of making a clean cut. Stressed grass is always more prone to problems.
St Augustine should not be mowed short. That promotes a shallow root system. Grass blades also protect the root system from the harsh Summer sun. In the Winter the grass blades act as an insulator to the root system. Suggested mowing height in those seasons is about 2 1/2 inches. In the Fall when the temperatures are mild you can lower it a bit to help with prevention of brown patch.
Mow in different routes across your grass so you do not wear wheel ruts from using the same pattern time after time.
In early Spring when your grass is coming out of dormancy you can mow your lawn low, bag the clippings and hand rake the lawn to remove most of the thatch that has accumulated during the last year. Dethatching St. Augustine grass with a power dethatcher is not advised. It does more harm than good.
Aeration has the ability to help decompose excess thatch and aid in reducing soil compaction. There are two kinds of aeration. Core and spiking. Core is the preferred method. Core takes a plug of existing soil out of the ground. There are manual core extractors but they would take a long time and be a lot of physical labor for an average size yard. Machines can be rented that would be a lot less work. If you have a sprinkler system be sure to mark your heads. After you have aerated, rake up the plugs.
Weed Control
When you want to prevent weeds you would use a pre-emergent weed control. This group of herbicides prevents weed seeds from sprouting. The most important time to use pre-emergents in your lawn is in the Fall and Winter even though they can be used at any time of the year.
When your St. Augustine goes dormant and turns brown for the winter any green weed sticks out like a sore thumb. Those winter weeds can be prevented with a couple of applications of pre-emergents used before the weeds germinate.
When you have an existing weed problem you want to use a post- emergent weed killer that will kill the weeds but not damage your grass. Most weed killers you find in stores kill broad-leaved weeds. Those are weeds that are not grass like. You would typically spray these herbicides in Spring for clover, dollar weed, dandelion, chickweed, dichondra etc. They tend to take about 2 weeks to for the weeds to die. Weed and Feeds are in this category.
During the warmer weather be very careful spraying weed killers in your lawn. They can do a great deal of damage if you use the wrong one or if you use them at too high a dilution rate or if you simply spray too much in a given area. Read the label directions carefully for all weed killers. The use of a spreader stickers really enhances the effectiveness of herbicides.
For nutgrass try the product SedgeHammer. It works really well.
For small patches of Virginia buttonweed try using AgraLawn Crabgrass Killer. The buttonweed will be dead the next day and not hurt your grass... even in the heat. For larger areas use Image. You can use this product in warm weather but it takes about 4 weeks to kill the buttonweed.
Bermuda grass will outgrow St. Augustine in heavy traffic or dry areas. If bermuda grass is becoming a problem and taking over areas of your St. Augustine you will have to either control foot traffic, aerate and water more.
Disease Control
Brown Patch is the most common disease in St. Augustine grass. It is a soil related fungus and is most destructive from September through December. The window of opportunity for brown patch in the Spring is usually very short, about 3 weeks. There are years, though, when it is even active in Summer because of very wet conditions. Brown patch tends to be circular and has a yellowish halo on the leading edge when the fungus is active. There will often be a small green spot in the middle of the damaged area. Brown patch will not destroy your lawn but it will thin your lawn and weeds can take over in those areas.
You will increase your chances for getting this fungus if you fertilize heavily and water too much. Be sure not to water in the evening, especially in the Fall.
Prevention is very expensive because fungicides tend to be the costliest chemicals per square foot of coverage. Fungicides typically would prevent fungus for only 3-4 weeks. With a 4 month window of opportunity in the Fall that would require at least 4 applications. For an average size lawn prevention is cost prohibitive for most homeowners.
Treating the spots as they appear is much more cost effective. When you see the spot start just treat that area and the area around it. The fungus will become inactive and stop growing. Reapply as necessary.
There is no need to treat inactive brown patch (no yellow halo).
Terraclor granules containing 10% pentacloronitrobenzene (PCNB) are the most effective and easiest to apply. For an organic control apply cornmeal and dried molasses in late July or early August as a preventative. If you want to control an existing brown patch problem organically you can use the product "Serenade".
Gray Leaf Spot disease tends to be a warm weather fungus. Grayish brown angular spots appear on the leaves. It can also cause the tip ends of the leaves to shrivel and the grass can thin. It occurs in periods of high humidity and high moisture. Over fertilization promotes this disease. Spray Immunox for control.
Take All Patch or Take All Root Rot. This is a very destructive disease that has been damaging lawns across Houston since the late 1990's. The disease resides in the thatch level of the grass. When the conditions are right the fungus attacks the root system usually during Fall and Winter. You do not see the symptoms during this stage. The disease is destroying the root system without you seeing any damage. When the warm weather comes the next year and the grass needs to bring moisture to the leaves, and it can't, it starts turning yellow and then proceeds to brown. Take All Patch sometimes gets confused with grubworm damage.
The best way to tell if it is Take All damage is to inspect the root system in the affected areas. If the roots appear white but very short or if they are black then you probably have take all root rot.
Experts have a lot more to learn about this disease. At this time there is no chemical cure. There are a few things we understand that limit the damage this disease can do. They are as follows.
1. Aerate and dethatch your lawn
2. Acidifying the soil to 5.5 pH
3. Mow less often and mow high.
4. Apply an organic compost material like peat moss, sheep manure or leaf mold compost.
5. Apply a chelated liquid iron at the first signs of yellowing.
6. Fertilize with organic lawn food. Do not fertilize with urea based fertilizers.
7. Apply a fungicide containing Mycolobutanil in the Fall.
Slime Molds : They look like dark oily spots in the morning on your lawn. Those same spots seem to turn grayish when they dry out later in the day. They are harmless to your grass. Hit them with a hard stream of water and they will go away.
Insect Control
Chinchbugs are the most destructive insect to St. Augustine grass. They are a warm weather problem. They can do damage from June through
October. They tend to attack in the drier areas of the lawn and often near concrete. If left untreated long enough they can kill an entire lawn.
The first sign of chinchbug damage is that the lawn looks somewhat yellow and dry. Even though you water it keeps getting worse. You can part the grass and spot them. Sometimes you have to look in several places. The adults are about 1/4 inch long, black with white wings. You may see an immature stage that looks brown with a white stripe on it's back.
When you confirm you have them you will need to treat. If they are found in the front yard then treat the whole front yard. You do not, necessarily, need to treat the backyard if you see no damage but you will still need to check regularly.
You can spray or use a granular application. There are many insecticides to chose from. Liquids kill them quicker but granular applications tend to be effective longer.
Grubs can destroy the root system of grass and kill sections of your lawn. Grub damage is not rare but somewhat unusual in Houston. Most yards have them in the soil. That does not necessarily mean that you need to apply insecticides. If you dig and find 8-10 per square foot then you need to treat. Several granular grub killers are available.
Sod webworms occasionally appear in the fall. They are small green worms that can eat the grass blades to the stems in a very short time. Female moths lay eggs in the grass. The initial damage looks like brown patch. The blades of grass will need to be inspected closely though. You can spot bite marks on the leaves. You can find those small worms but it is not easy. When the damage is severe there is a webbing along the ground. The lawn does not die. It just gets chewed down like a grazing animal was there. The same insecticides that kill chinch bugs work on sod webworms.
Leveling
If your lawn needs leveling there are some basic things to remember. Topsoil or sand are fine to use as long as there is not a lot of clay in them. Be sure that the grass is actively growing and don't smother the grass by putting more than 1-2 inches on at a time. You will be bringing in weed seeds with this new soil so be sure to apply a pre-emergent herbicide.
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