Landscapers need to know just as much about trees as arborists. There ain't no middle ground. One good free resource is Online Seminars for arborists. http://on-line-seminars.com That's 10 new, easy to read articles every 2 months. Skip the quiz, or take them for fun. I go for credit to get ISA CEUs Check it out. Isn't a landscaper in town that should know less about a tree than an arborist. And almost vice-versa.