Weedwhacker, there is a senior service that some folks do not know about. Lower feels for some.
Audreygb55, welcome. Keep those ideas flowing. Ya might want to take a master gardener class first to broaden your knowledge. This time of year you will see unkept yards and gardens due to the cold and folks don't cleanup until spring when the weather gets nicer. As I have been told by some gardeners they leave it for the birds and critters during the winter months. Some gardeners will tell you that cleaning up isn't a good idea.
I can tell you from my experience when folks see our gardens........we are not the Norm. Then the next thing I hear is whom is your gardener so we can hire them! You will find some folks won't keep up your hard work also. Also check with the State requirements for running a business and their requirements. While going to school this might not be a job as it will require more of your time even with a small handful of clients. Some folks will be demanding of your time.
