Lawnholes

We used to use a 'professional' lawn company to treat the lawns.  It wasn't cheap and still didn't do all we wanted.

Today we hired an aerator and covered twice the area, more thoroughly, for a third of the price.

We ummed and ahhed about spikes or holes, these being options for the aerator machine.  In the end we went with holes as it was recommended for the sort of heavy soil that we have although it does leave the plugs all over the place.