By Todd Layt
Palmetto® buffalo grass will greatly increase its thatch over the years unless you manage it. But don’t worry too much, dethatching is a relatively simple task, often just mowing it short will do the job. With most Buffalo types (bar a few) you usually need to dethatch yearly but if you have a Palmetto® Buffalo lawn, dethatching only needs to be done every 2 years.
(Above) Mow your Buffalo lawn short so that you can just see dirt through the crisscrossing runners that have been scalped down. Make sure some runners are left above the soil. If the lawn is very thatched, follow the advice in this article and dethatch over two separate dethatching mows.
Over time, Palmetto® Buffalo grass runners (stolons) will grow over the top of each other, eventually smothering the runners and leaf underneath. The smothered runners and leaf eventually die off and the dead thatch underneath becomes problematic. Left for many years a thick layer develops which causes a number of problems.
In severe cases the runners on top of this thatch layer can have problems rooting into the ground below which makes the lawn weak and susceptible to drought, pests, and lawn disease. It also gives the lawn a tired look and reduces new growth which is the sign of a healthy lawn. To fix this you need new growth growing close to the soil level.
There are three main methods of achieving a nice low thatch Palmetto® Buffalo lawn.
The simplest and easiest method is to mow the lawn short once every two years but it will benefit from a yearly short mow. If you do it every spring, the scalping heights do not need to be quite as low. Simply drop the mower to a very low height and scalp the lawn. The notch setting depends on the mower brand. Make sure there are runners still left covering the ground.
What you are doing is basically a controlled heavy scalping of the lawn. Make sure you collect all the clippings. The easiest way to do this is mow once at a level just a little shorter than normal, using the catcher to collect the clippings. Then turn around and mow again straight away, this time dropping the mower down to a level where you actually see a small amount of dirt showing through the runners crossing the ground.
Make sure there are still lots of runners crisscrossing the ground though. Fertilise the lawn with slow release fertiliser after scalping and water well for the next 2 to 3 weeks. An even better method is to fertilise your lawn with slow release fertiliser 4 weeks prior to scalping. This will get the lawn actively growing and make it reshoot quicker after scalping. (This is optional).
If you do this every year you will find that you will not need to scalp it as heavily or mow as low as compared to doing it every second year, and the scalped look will only be there for 10 days or so. The best time to do this is Mid-September in Queensland and Northern NSW, and early October for Sydney and Perth, and Mid-October for Melbourne and Adelaide.
If you have a weedy lawn, it is recommended to use a pre-emergent on the lawn. The only one available to the general public is Oxa Pro. This has a combination of slow release and Oxadiazon. Apply this after scalping the lawn and water it in well.
What do I do if it is an older lawn and the thatch is really bad?
If you have not mown the lawn short for many years, and the thatch level is really high, you may need to lower the height of the lawn gradually over a month or so. In a very high thatch Buffalo lawn, the runners on top may not be reaching the soil below, and may actually be rooted into the thatch. The runners below that top level can actually be very weak, and the runners at the bottom of the lawn can even be dead.
In this case you need to remove the top layer, leaving the layer below (Middle Layer) to reshoot and root out into the soil. This should happen after about a month or two. Some of the bottom dead looking runners by then should have reshoot, and some of the mid layer ones you have rejuvenated will have grown down a little and will have rooted into the ground. So when the lawn looks healthy again, you can take it down another notch or two on the mower removing some of the middle layer of thatch, exposing the bottom layer.
Remember to always collect the clippings. If the fertiliser is running out re-apply another application of slow release after the second short mowing. Water well for a few weeks, and you will have a rejuvenated lawn.
Using a dethatching machine.
As Palmetto® Buffalo does not have underground runners (rhizomes) this method is not as critical for Buffalo as it would be for Couch or Kikuyu. A mower works almost as well, but dethatching machines are still suitable for Buffalo turf provided you do not dethatch to soil level. If you go too low and remove all the above ground runners you may lose your lawn.
So when using one of these machines, make sure you can still see some runners crisscrossing the ground. The same rules apply for the first method. Remove the dethatched grass and take it away. Fertilise as per the first method, and use a pre-emergent if you have a weedy lawn. If it is a very old Buffalo lawn that has very high thatch you may still need to dethatch twice, removing half the first time, and the rest the next time, so it may be easier to use your mower rather than hiring a specialised machine twice.
This is particularly good for very old Palmetto® Buffalo lawns with very high thatch. Provided the level of the lawn is not already too high, this is a great way to rejuvenate your Buffalo lawn no matter how heavily thatched. Buy Organic sandy loam top dressing mix from your local supplier. Simply spread the mix over the top of the lawn. The height depends on the thatch level, but a good rule of thumb is to spread the mix over the lawn with a shovel, then rake it out so some of the leaves are still showing.
This is very important. If no leaves are showing you may have gone too deep and can smother the lawn. If leaves are showing you will be fine. Prior to topdressing, an application of slow release fertiliser will really help the lawn. Having it below the top dressing mix really helps. It is recommended to top dress at least every 3 years provided the level of the lawn is not too high above paths or drainage points. Top Dressing is also great at fixing undulations and uneven parts of the lawn.
Combination of methods.
Using the mower method for two years in a row, then topdressing the lawn every third year is a great combo method. It gets organics into your lawn every third year which really helps the lawn quality. It also reduces the work required as it is easier to scalp the lawn two years in a row, then top dress every third year. After all most people with a lawn have a mower with a catcher.
When buying a mower for future dethatching.
Make sure it has a catcher, and it has some lower settings on the mower. Honda Mowers for example have really good lower mowing heights. Also sharpening the blades, or putting on new blades before scalping or dethatching will give you a cleaner cut.