Just to move away from the blow and go guys, I implemented a full service plan to all of my custom design/install clients after spending a year or so protecting their investment...and mine, at a minimal cost. Most of my clients have signed up on an annual contract with everything all-inclusive with a few select services that can be added on an as needed basis. We also offer licensed irrigation checks and chemical applications including pest, fertilization, and weed control which are included in the contract.
We maintain their lawn, trim, prune, treat fungus, pests, make irrigation repairs (billed hourly plus materials), apply mulch twice a year or as needed for a new plan. It works great, gives us "full run" on their property, and keeps my install, and their property, so much better than the neighbor. Clients range from 4,700 to 10,200 annually and are all residential in the Austin metro area.
Granted, I also have a personal interest in their property since I designed and built it, so the sell was easier than a contractor from off the street, but that is the reason I started my business...to make a GOOD name for local contractors.