You would be very well connected when you get to know your local areas gardeners. These people can be an inexhaustible supply of new customers. The majority of gardeners don't invest in the equipment required for aeration as their service is more general care oriented rather than specialized like aerating. They do however welcome an opportunity to service their customers by recommending your service to their clients. Sometimes they may request that you perform the jobs and then bill them instead of the customer. This is a benefit to the both of you then as he can make a mark-up on the service as well.