I'm impressed to see that 14 year old kids are wanting to work and even have business ideas of their own. Go for it mean, don't borrow money if you don't have to. You can do it, when I was a kid I mowed lawns in the summer with my home mower, worked out fine. This is not rocket science. You might want to look into getting legal though if you plan on doing this for a long time.
I'm sorry but some of these posts are pointlessly negative. The kids 14 years old for crying out loud.
What JCLawn_and_more said might work. Donno, but I wish the best of luck to you.
Read books on small business, marketing, accounting etc, reinvest. Your biggest problem will be transportation though lol. Are you in a rural area or in a neighborhood that has lots of potential customers? Even if you fail, learn from what you did wrong, use it in the future, plan your steps etc. Constructive criticism is very good, but at the end of the day your going to have to learn things on your own.
Goto this youtube channel: http://www.youtube.com/user/lawncaremillionaire
Watch as many of those videos as possible. Then come here and read all the cons as well. Balance it out, create a plan, set a goal thats realistically achievable. I'm 23, I have 2 jobs, both pay good, but I want to quit my less paying job because I figure mowing might bring more money for less time. I've been working on my biz plan for almost a month, I'm finishing up E-Myth revisited, and also working on Financial Accounting by Weygandt, just so I can have a clue as to what I'm getting myself into, as far as accounting, marketing, and management is concerned. GO FOR IT man, your young. Save your cash, don't get in debt. Theres no reason to, just take your time, and plan plan plan.