Hollow tining is the practice of sinking a hollow steel tine into your grass surface and removing the plug of grass and soil. This will then be deposited temporarily on the surface. This is then removed and topdressing is spread and worked in.
The aim of this is to aerate your lawn, allowing air down to your grass roots. It also reduces any compaction your lawn has sustained.
You should be aiming to get down at least 3” and preferably 4” or 5” although you will require a machine to achieve those depths.
I prefer not to use a solid tines as it has the effect of squeezing and smearing the sides of the tined hole. It is better than nothing but not as good as removing the cores.
Some people recommend spreading the cores back out over the surface, however I strongly advise you to remove the cores to your compost heap for the following reasons.
The soil brought to the surface by this technique will contain dormant weed seeds from below the lawn layer. These will germinate on the surface of your lawn.
You should use this opportunity to perform “rootzone replacement” where we are looking to amend and improve your rootzone over time. Giving it a topdress with the correct, balanced free draining but fertile product to help improve the long term drainage, aeration and fertility of your lawn.