Top Dressing a Lawn with a Trulute
The term is often confused with a fertiliser application as a 'dressing'. Top dressing is typically applied in the autumn after scarification and aeration and over seeding when around 8mm or 1/4 of an inch of material is applied and worked into the lawns' surface.
All top dressing material must be dry, preferably kiln dried for loams. Clay based loams should be friable and screened but not kiln dried. How many times have I tried to top dress a lawn with wet material? It is a nightmare to spread evenly. The lawn in the picture had been severely scarified and aerated and over seeded hence the colour, the lawn was not well!'
The lawn should be mown as low as possible and scarification and aeration carried out beforehand. You can easily make a real has of top dressing and make work hard for yourself. Pick a nice dry and ideally slightly windy day. Knock the dew of the grass or lawn beforehand to ensure the surface is as dry as possible.
Start by getting hold of a Trulute. A fabulous Groundsman's too, with a smooth and rough edge, it will quickly glide over the surface of the lawn and work the dressing into the surface. Concentrate on the edges first and try not to get any top dressing material in the borders, as it is a waste and you end up upsetting the gardener!
Get a wheel barrow, fill with desired top dressing material and around the edge of the lawn, a few feet in from the edge, carefully tip one third of the wheel barrow. With the Trulute, run it backwards, ensuring you get the loam onto the edges of the lawn as you work backwards. If the lawn's surface required the top dressing because the micro levels are just so bad, the lawn will take it. When you have run out of soil behind the Trulute, tip the next third exactly at the point where the last pile ran out and repeat. Do two sides of the lawn, up and down and across, by one or two passes off the Trulute. Then start on the main area of the lawn. Work out which way is the easiest way to run with the Trulute before you start. Tip the next third of the wheel barrow on the inner edge of the perimeter strip and work in very straight lines across the lawn until the top dressing material has run out. We tend to always use the rough side of the Trulute to move the dressing then the smooth side to run over the lawn at the end in lots of directions to work the dressing into the surface.
You could also use a plastic or flexible steel Drag Mat. When you tip the next third load of top dressing material, make sure that all the piles join slightly so when you run the line of dressing back across the lawn the lines of dressing as you work join up, but with no ridges from excessive material like the pictures shows. When you get to the other side of the lawn, complete the edge first like you started and fill the area in carefully so nowhere is missed. It’s a bit like painting by numbers. If you do not work in straight lines, it is a nightmare and you will make a hash of it. Spinning the top dressing off the edge of a shovel is also not ideal as it leaves 'arcs' of top dressing material and encourages ridges. You can also get mechanical top dressing machines that take around 0.3 tonnes and are powered both to the wheels and belt and brush which distribute the material over the turf surface.
We tend to use recycled compost which is screened from 0mm to 10mm. This is the by product of home owner green waste recycling schemes. The end product is some 50% soil and 100% organic too. It can actually be a bit warm as it holds its heat so make sure it is cold before you apply it to a lawn otherwise it can kill the grass as it is too hot. It is light and friable and the new grasses sown underneath can easily germinate through it. You do sometimes get a few really small twiggy bits that could be some 5mm long but the first mowing session normally gets rid of these.
Always start top dressing furthest away from the top dressing stack and remember to keep it dry. When the complete lawn has been top dressed, run over it with the smooth side of the Trulute and lightly glide the Trulute over the surface of the lawn making sure you have even coverage and thickness with no excessive amounts of material in any areas of the surface apart from where you can see a natural hollow has been filled. If the lawn does not need the top dressing material in a particular area, the lawn will not take it.
As a general rule of thumb, some London or City lawns will always need more top dressing material, typically up to two tonnes per only 100 sqm size. We aim for 1 Tonne per every 200 sqm of lawns unless they are really uneven.
Remember that you could hollow tine a lawn and remove a turf 'plug' into which a more desirable top dressing material should be introduced. You will need far more top dressing material on a lawn that has been hollow tines as it needs to go down the holes and then top dressed again until the holes are full to the top after some rain hopefully.
If you have existing grasses to content with following top dressing, mow the lawn on day ten then keep off it for a further two weeks at such time the new grasses will be germinating. Then take off up to 25% of the grass growth, no more.