Lawn top dressing

Why top dress the lawn

Lawn top dressing is an important operation that should be carried out at least once a year on the lawn. Top dressing is the process of applying a fine layer of high quality soil to the surface of the lawn. Materials commonly used for top dressing are loam, sand and peat, depending on the chemical and physical make up of your soil or root zone. The reasons for top dressing lawns include.

• Create a Level Surface: If you have a lawn with minor undulations and hollows, regular lawn top dressing will gradually true the lawn up by filling the hollows.

• Improve the drainage: Top dressing can be used to improve the drainage on a garden lawn especially after aeration has been carried out. E.g. If you have a heavy poor draining soil (clay), by aerating you create channels into the soil profile. Then by following up afterwards by top dressing, using a suitable sandy top dressing and working it down the holes you will improve the drainage. This is because sand drains better than clay due to the larger particle size that encourages quicker water movement.

• Improve drought resistance: This is similar to improving the drainage on a lawn but you would use a peat and loam based top dressing. Peat and loam have greater water retention properties than sand, therefore they would improve the drought resistance of your lawn.

• Thatch Breakdown: A good lawn top dressing program can help with the decomposition of thatch. By applying top dressing it helps dilute the thatch layer and encourages natural breakdown.

• Encourage a Thicker Lawn: Lawn top dressing encourages the grass to product new shoots resulting in a thicker, tight knit sward, therefore reducing the invasion of weeds and moss.

Materials that are used for lawn top dressing

As we have previously noted lawn top dressing is made from 3 different materials, these materials are:

• Sand: Choose a sand that is lime free (with a pH below 7), this is because excess lime can encourage weeds, disease and worms. It is also important that the sand contains a high degree of medium size particles, avoid sand which contains a high percentage of very fine particles.

• Peat: Go for a quality sphagnum or sedge peat. Peat is very useful on sandy free draining lawns that suffer during drought conditions, as peat has good water retention properties. However if you lawn has a high clay content then peat should be omitted from the lawn top dressing mixture.

• Loam: Choose a loam that does not have a large clay content. If possible visit you local garden centre or supplier and locate a good quality sandy loam.

When choosing these materials you will need to take into account what soil type your lawn has, as this mill make a difference in the ratios each material will be used.

E.g. A very heavy clay lawn with poor drainage would not require any peat, as this would only add to the drainage problems. Instead you would want to use a higher percentage of sand to help improve the drainage of the lawn.

On the other end of the scale, for a free draining sand loam you would want to apply less sand and add more peat and loam to the lawn top dressing. This would help improve the water retention of the soil, and would improve the drought resistance of the lawn.

Guide for lawn top dressing mixtures

It is important to note that the following mixtures are not set in stone, they are only an example of what you might want to use on your particular soil type.

• Sandy soil - 4 parts loam, 1 part peat, 1 part loam.
• Loamy soil - 2 parts loam, 1 part sand or 4 parts loam, 2 parts sand, 1 part peat (if water retention is an issue).
• Clay soil - 4 parts sand, 1 part loam.

When to apply a lawn top dressing

Lawn top dressing can be applied any time during the growing season. However the most suitable time is late summer as part of the autumn lawn care renovation program, when there is still some good grass growth left to help the lawn recover.

The autumn program starts with scarification and aeration (preferably hollow tining to get the full benefit of the top dressing). These two operations create a good seed bed prior the grass seed being sown.

Once these tasks have been complete the top dressing can be applied and rubbed into the lawn.

A similar program can also be adopted during the spring, especially if moss removal has left the lawn with very little grass cover.

How to apply a lawn top dressing

The following tips on applying a top dressing to the lawn will help the jobs go smoother with out any problems.

• If possible do this task when the grass is dry, a nice breezy day is ideal for top dressing the lawn, as it keep the grass dry and helps the top dressing dry quickly when it has been applied.
• Prior to applying the top dressing, mow the lawn. If possible mow it a little shorter than normal as this will help the top dressing go down the aeration holes, it will also make the rubbing in process somewhat easier.
• Once the lawn has been mown spread the seed over lawn, if you intend to overseed.
• The next step is to tip the top dressing mixture into equal sized heaps on the surface of the lawn.
• Using a shovel, the top dressing can be spread as evenly as possible over the lawn. A typical application rate would be between 1kg - 4kgs. Use the lower rate if the lawn has been spiked, if it has been hollow tined use the higher rate as the lawn will absorb more material, due to the larger aeration holes.
• Once the top dressing has been applied it will need to dry prior to rubbing down into the aeration holes and the grass. many tools or implements can be used for this job, including a wide sweeping brush, back edge of a rake, true lute of drag mat.