Thatch is a tightly woven layer that lies beneath the visible grass blades which is found between the grasses’ above ground shoot that’s green and the below ground root system. Generally, thatch is comprised of stems, leaves and roots, some living, some dead and forms a natural part of the turf’s growing process. While the presence of some thatch is good for the lawn, too much of it can cause problems. Thatch contributes to lawn health as long as it does not get thicker than ½ to ¾ of an inch. Depending on the type of grass you have and the climate which you live in, it’s important to choose the right time of year to dethatch your lawn.
The lawn should have the best chance to recover as dethatching can be tough on the surface. It’s not advisable to dethatch the lawn if the region experiences a heat wave or is in the middle of a drought. There should be 45 days of good growing conditions for the lawn after dethatching so that the grass has ample time to recover without letting the weeds take over. Early fall or late spring is ideal for dethatching, but a lot depends on the grass and the type of weather conditions it needs to grow and flourish. There are several benefits for dethatching your lawn:
- Improves mower traffic and turf tolerance
- Insulates grass crowns from temperature swings in the soil
- Slows down water loss and mulches soil
- Decreases compaction and cushions soil
- When the thatch develops into thick layer, it forms a wedge between the soil and grass which diminishes lawn health and causes problems like:
- Blocks sunlight from reaching the lower glass blades
- Holds back moisture against the glass blades, which in turn causes the formation of diseases
- Creates an uneven lawn surface, which leads to improper mowing and scalping
- Forms an impermeable layer, which prevents fertilizer, water and insect/disease control from reaching the soil
- Forms a shallow rooted lawn caused by blockage of soil so that grass roots grow into a nutrient-lacking thatch
What causes Thatch formation?
Some situations can result in rapid formation of thatch even if it does form naturally. Overwatering the lawn, mowing too high, overfertilizing with too much nitrogen and using heavy clay soil for the surface can cause thatch formation. There are certain types of grasses that tend to form thick layers of thatch. Cool season grasses and creeping turf types can quickly form thatch when the turf has not been properly fertilized, the soil is too compacted or it has been spread by above and underground stems. Healthy practices to prevent thatch formation include leaving grass clippings on the lawn and using a mulching mower. This is because grass clippings can decompose readily and thatch arises from stems and roots from the top inches of the soil that die and do not fully decompose.
Does Your Lawn Need Dethatching?
To know if your lawn needs dethatching or not, you can undertake some of these tests included below:
Inspect the lawn – Examine your lawn closely and determine how thick the thatch is. If the soil isn’t visible between turf crowns, it is likely that you are looking at a thatch layer. Check to see if you can shove your finger through the visible thatch. If it’s impenetrable then that area has to be thinned down.
Feel the lawn – If the lawn is bouncy underfoot and spongy with a springy feel, then it must be having a thick thatch layer.
Measure the thatch – You can excavate a lawn sample to examine the thatch. By using a spade or trowel, remove a layer of grass and soil which is about 3 inches thick. Measure the thickness of the thatch layer that is lying directly on top of the soil. If the layer is ¾ or more in an inch, it is time to dethatch.