I bought two commercial mowers at first and racked up around $7,000 in debt. I only had about 10 customers at the time too. My best advice I give to all companies, do not go into debt unless you can pay off that debt within a years time. If you don't, it will just hurt you in the long run by limiting your purchasing and budgetting procedures.
Try to purchase every in cash or in credit if you can pay it off in a year. Sure, truck purchases are the exceptions though. If you need certain items now and then, such as aerations, walk behind leaf blowers, dethatchers, etc. I would suggest to rent them. You actually will save money in the long run.
My best advice though for you right now is one of two things; grow big and fast now to pay off your equipment, or sell off itesm that you do not use and use that money towards your debt.