1. Starting with the first one, we know we all could use lawn signs more often.
2. Phone calls. Let's think creatively here. What if you talked to your customer base and asked them to put their feelers out and make some calls. Maybe say you wanted to do some community service work.
Are any of your customers a member of local groups that could ask around and see if there is a family who really came down on hard times who could use a yard cleanup to help them?
Maybe your customers would then make calls for you about this.
What about offering some sort of lawn care package they could raffle off in their local groups (fire dept, rotary, ladies clubs, etc etc) to raise money for their group?