The four most important qualities to assess in hiring someone to create your gardens or landscape for you are; Talent, Capability, Integrity, and Compatibility. A not very talented person you like, who is capable and of high integrity will do a great job creating for you a garden not worth having.
A talented person without capability will give you an inspired design that can't or shouldn't be built, a person who is talented, capable, and of good integrity that you don't get along with is a poor choice and a person without integrity will let you down in every way. You can also get Best Landscaping Services in Maryland by Local Landscaping Company.
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How can you know these things about someone? Your own instincts, to begin with. If you don't have a good feeling about someone, stop right there. Beyond that, always ask for references if you have any doubt and no matter whether you are dealing with a landscape architect or a gardener, ask to see a portfolio.
Keep in mind though, that everyone has to start somewhere so he may not have much to show. Anyone with any kind of education in the field should have design projects to show at least and these are worth seeing.
Let him explain his drawings, tell what he was trying to create, and see how you resonate. If he has built gardens or hardscape elements, ask to see photographs. This applies equally to the landscape architect as to the garden designer. His degree does not bestow nor even indicate talent and you have a right to know what kind of a designer he is.