You should undertake top dressing to repair holes or uneven lawn just prior to the growing season, usually the beginning of Spring; not when the lawn plants are in their dormant phase or you run the risk of damaging or even killing the lawn entirely. Top dressing for nutrients can be applied at any time. Do not top dress on an annual basis regardless of popular belief as this will just accelerate the build-up of thatch. Avoid top dressing if rain is predicted as the wet weather will make the dressing difficult to deal with and make levelling troublesome.
Top Dressing for nutrients
This type of top dressing application places a thin layer of organic soil mixture over the area of your lawn and adds organic, natural nutrients and minerals. You would apply a top dressing for nutrients if your lawn is in need of a boost as it will encourage the production of new shoots and result in a thicker lawn with the added benefit of then hindering moss and weed infestations. Applying a top dressing will introduce materials to your soil that will improve drainage, allow the soil to exchange gases with the atmosphere more effectively while also promoting the development of the soil’s micro-flora and micro-fauna needed to break down thatch and grass clippings. Top dressing matter will feed the earthworms too, releasing nutrients into the soil. An added bonus is that top dressing allows the soil to retain moisture better during drier conditions as well as allowing excess moisture to drain away during heavy rainfall.
Bags of top dressing mixtures are readily available from turf farms, lawn care centres and nurseries and provide all the relevant handling and application information. Work out the size of your lawn before you buy; as a general guide a 2kg bag will be enough to top dress a square metre of lawn.
Mow your lawn the day before applying the top dressing and rake up and remove any debris to allow the nutrients to effectively penetrate into the soil. Firstly shovel the top dressing into even piles around the area of lawn and then rake the mixture into the lawn until it looks as if the lawn has been lightly dusted and the tops of the lawn plants are above the dressing. Rake in a figure eight motion so that the top dressing mixture is spread evenly. Hose the lawn thoroughly so that the dressing is barely visible.
Top Dressing to fix holes and uneven lawn
Once again mow the lawn the day prior to applying the top dressing; the longer the grass the more sandy loam or clean river sand required to cover the area and a deeper layer of soil will make it harder for the grass to grow through it. Speak to your local landscape supply company for a recommendation on the amount of loam or sand required for the specific area you need to address.
To even out the lawn
If the area of lawn requiring evening out is only slightly uneven then you can apply a top dressing up to 12mm at once. For areas that are deeper than 12mms apply one layer of 12mm first and then add another layer. Shovel the loam or sand onto the lawn in even piles and then level with a garden leveller. The top of the lawn plants should remain visible. Once applied and the lawn is even water in the top dressing.
For the repair of a hole deeper than 5cms use a shovel to raise the grass on top of the hole, place top dressing material underneath to elevate the level of the lawn. Then apply the top dressing to address any remaining unevenness as per the instructions above remembering that the tops of the lawn plants should remain visible and the top dressing needs to be watered in once evenly spread.
Fertilise; before or after?
The recommendation is to fertilise the lawn a week to two before applying a top dressing regardless of whether this is for nutrients or to repair holes or an uneven lawn. This boost to the lawn plant’s growth will assist the turf to push through the dressing more easily and quickly.
What you should do after top dressing is to water your lawn. Water just after the application and then maintain regular watering to give the lawn plants a boost after what is a stressful process for them.