Originally Posted by Banksy
If going back to college to get a degree is not a realistic option, where else can one learn more about horticutlure or at least some solid basics?
Look for training seminars through PLANET, if not associations more local to your area.
Here in GA there's the Urban Ag Council, GGIA, UGA Extension Events. Georgia Certified Landscape Professional, etc.
I don't know what's available in your area, but at minimum, I'm sure there's a state master gardener program.