If you have already done some gardening and you are very interested in that subject you should consider taking gardening courses.
It of course depends on the special course but all gardening courses should cover topics as plants and vegetables, greenhouses, shrubs, trees and lawns. These topics will be examined from the point of view of gardening experts. In those courses you can get the knowledge about how and why things in gardening work like they do.
Nowadays there are also possibilities to take these courses at home. You can search for information on the internet and order the materials at home. Special books and DVDs are mostly included in that package. In the last case you can plan yourself how much time to invest at home but even then the average time is one year during what you can get new materials.
Gardening courses can help you to improve smaller gardens in the suburbs or bigger ones in the countryside. New challenges can include rock gardens or greenhouse cultivation. Almost everything you want to.
These courses might cost a lot so consider them only if it is your dream to work more outside in the fresh air free from the atmosphere of your work place. These courses can also help you find a job in gardening if you find out that that is what you really want to do.