I would like to get to get some landscape design jobs, to do in the summer as a freelance designer from my home. Because it would be seasonal and only a few designs per season do I have to get a sole business license, pay quarterly taxes and do all of that? I have some business cards with my number, name and all of that and it would be just person to person referrals unless it took off then maybe more.

Whether you need a business license depends on local laws. However, if you have income from your freelancing, then you do need to report it. Use a Schedule C.