Want to know what to use when top dressing your lawn? First it's important to determine what outcome you're trying to achieve.
Depending on whether you're top dressing to correct poor soil preparation, improve deteriorated soil quality or permeability, or to fill in holes and correct uneven areas in your lawn, the answers will be different.
And if your lawn is well fertilised, healthy and level, then it's possible you don't need to worry about top dressing at all.
Top dressing can bring new life to a lawn that's looking a little shabby, including helping to reduce the build up of dead grass clippings and stems, known as ‘thatch’. It also helps to allow for water and nutrient retention, improves drainage and increases disease and pest resistance.
When should I top dress my lawn?
Top dressing should only be completed during the growing season (this is when you need to mow your lawn weekly) and the earlier in the season the better. Don't attempt it when the lawn plants are in their dormant phase or you run the risk of damaging, or even killing the lawn entirely. Generally late spring to early summer is best.
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. Also, 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 to improve soil profile
When you're top dressing to improve the profile of your soil, you're aiming to promote a healthy root system that will protect the turf from weather conditions such as droughts and winter frost. Your lawn needs a firm base to allow for water retention and for water to move through the soil, so the turf roots system can develop and establish.
A good soil base for most turf varieties should include the following:
- Washed river sand - medium to course particles with some clay present to compact and form a firm base.
- Some heavier soil to help retain moisture - this can be mixed with the sand to create a free-flowing profile for water movement.
- A composted material mixed in - such as green waste, chicken or animal manure and some natural nutrients to help balance your pH levels.
If your lawn is looking a little lacklustre, compacted or lacking in nutrients, we recommend applying a sandy loam. This is suitable for most lawn situations. These top-dressing soils are similar to the soil or turf underlay that is spread prior to laying turf. These usually consist of a blend of 80% washed sand, combined with 20% black soil or organic material. If you have a sandy soil, it's a good idea to use a higher proportion of organic material.
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.
Be sure to 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 the top dressing mixture is spread evenly. Hose the lawn thoroughly so the dressing is barely visible.
Top Dressing to improve levels
If your top dressing goal is to achieve level improvement, we suggest using washed plasterers' sand. It doesn't compact quite as hard as bricks' sand. It's also easier to screed and level due to the lower clay and silt content and reduces the likelihood of the surface crusting over and repelling water.
If you're after a really flat lawn surface and intend to mow your turf variety quite short, then a straight sand is your best option. Just ensure you include the addition of fertilisers and nutrients that your lawn needs within your broader lawn maintenance schedule. Lawns that are cut shorter tend to require a little extra loving to help them perform at an optimum level.
Again, remember to 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.
Top dressing 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.
Top dressing to fix holes in the lawn
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.
How to top dress a lawn
Topdressing should be applied at no more than 5-10mm in thickness at a time. Rub the sand or sandy loam in evenly using a lawn level bar, and work the sand down into the turf thatch layer.
To prepare your turf for topdressing, apply a general-purpose fertiliser and a wetting agent, and water in well a couple of days prior. This will give your turf the growth required to break up and through the topdressing sand.
When to fertilise
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.
Be sure to water your lawn after top dressing. 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.
For more helpful lawn care tips click here.