Honestly, the experience you would gain by working for a real landscaping company for the summer will be just as valuable as the actual cash you will earn.
Instead you're going to end up wasting an entire year struggling just to find the gas money to serve the handful of customers you will have and you'll be stuck in the same situation next year. No money to start a real business and no money to go to colllege.
Take advantage of your living situation. Get a job with a landscaping company and save your money. Most of the questions you've asked in this thread will be answered and you'll also gain the skills to start your business off with a good reputation. You might even find out that this isn't what you want to do.
Without capital and credit your business can't succeed. What are you going to do when your car breaks down? How many times can your parents afford to bail you out? What happens when your mower inevitably wont start? Who's going to fix it and how are you going to pay them?
I applaud your ambition, but what you're doing right now is more like creating a summer job, not starting a business. Let someone else take all the risk for now and you can just worry about working hard, learning about the business and meeting people in the industry who could be a huge asset when you are ready to startup. With your attitude you should have no problem finding a good job in the field.