Is top dressing grass important?
Updated: Apr 27, 2021
Who eats cake without icing ? Topdressing your grass is like icing on a cake.
It's not too thick but adds that sweetness in the form of nutrition, extra drainage and helps to maintain a healthy lawn.
Why top dress your lawn?
To maintain a stand-out lawn , include top dressing in your spring calendar.
Like icing on a cake, top dressing needs to have all the necessary ingredients to make the effort worthwhile.
Here are some tips for keeping your lawn healthy through a hot summer, promoting autumn root growth, and keeping the lawn in shape during winter.
Reasons to top dress:
The lawn looks pale or discoloured (during its active growing season) due to a lack of nutrients or good soil.
The soil is a bit heavy underneath, and the lawn is patchy (be aware that this may also be a fungal problem).
Lumps and bumps need to be leveled out that scuff the lawn when cutting.
Hollows, gaps and strips need to be fixed up where a new lawn was poorly laid.
Topdressing can improve lawn health when problems like lawn disease can be ruled out.
Benefits of top dressing.
Top dressing increases the health of your grass by providing extra nutrients and better drainage (especially if you have just aerated the lawn).
Spreading sandy loam soil between the ground and midway up the leaf blade can prevent thatching, and prevent undecomposed dead grass to cause problems.
Annual topdressing is recommended for lawn health.
Best time to top dress your lawn.
The best time to top dress is when a fortnightly mow is just not enough. This means you have reached the peak growing season for your lawn.
Healthy lawn growth will help the grass recover after top dressing.
The best time to top dress in warmer areas is spring but in cooler climates it may be late spring to early summer. This is due to late frosts slowing grass growth in September and October.
Top dressing in winter or cooler periods is a no-no, as the lawn is not actively growing to use the top dress soil you provided. In other words, do not top dress in cold periods as the lawn will struggle to cope.
Top dressing in really hot periods is also a no-no unless you are prepared to do follow up watering to help the lawn recover healthily.
Top dressing in the peak growing season will assist your lawn to recover strongly.
How to top dress your lawn (Step by Step).
1) Two to three weeks before you top dress, spread a quality fertiliser over it, and water it in. This way you will strengthen the lawn with the right nutrition leading up to top dressing (Some types of fertiliser [like organic forms] need more time to work than others).
2) The type of top dress soil you put on your lawn is important. Consider sourcing the correct sandy loam soil, or a sandy dressing that will be right for the lawn. You don't want a top dress that is too heavy in organic material, or too light on sandiness.
Remember, the sand particles are really useful for providing bigger pore spaces in the soil for water and oxygen to flow - so a sandier soil is better.
It also needs to be like grandma’s custard - no lumps. Ask your soil supplier to guide you with choice.
3) Calculate the area to be top dressed in square metres, and then multiply that number by 0.01 as you want 10 mm of topsoil to top dress.
Remember, top dressing is only the icing on the cake. Deep latherings of topsoil can make your lawn sick.
4) Cut your lawn evenly before the top dress ensuring you have the catcher on.
5) Wheelbarrow soil to make small piles evenly across the lawn. Smaller piles will help you to ensure the 10 mm cover needed when you rake the soil across the lawn.
6) Rake the soil piles in with a metal rake so you can turn it over on the straight side to level to the 10 mm depth. Be careful to have the grass blades popping up above the layer of top dressing soil.
7) Use a soil leveler (if you have one) to work the soil into the lawn. This is an excellent tool for any lawn enthusiast to have.
This is an excellent tool for any lawn enthusiast to have.
8) Once the soil is worked in, give the lawn a good watering to settle the soil further down into the lawn. You want to get the top dressing soil into the thatch layer.
Be prepared to do a good, follow up watering after top dressing to settle in the new soil.
Chris Hinton (Assoc Dip Hort, B. Arts B. Teach [Hons]) is a horticulturist with over 40 years experience and is the Co-Director of Ezi Mat subsurface irrigation. His resume includes roles in horticulture education, landscape construction management, landscape design, interior plantscaping, horticulture marketing and retail and wholesale production.