Landscaping, as it applies to the home gardener incorporates three major design concepts:
First and foremost though, it should be fun!! If we wanted to take the fun and enjoyment, as well as the personal satisfaction of DIY out of it, we would hire a professional.
Here is an excerpt from Wikipedia which helps at least get the concept down from a technical standpoint. Later we will approach the concept in a more practical sense as it applies to the home gardener :
What we want to accomplish as DIYer's is to learn a little about both the design and the architecture concepts and tie them together with our garden design. We, as home gardeners will focus more on the design elements, and later on, briefly touch on the architectural components.
There are a number of Design elements you can choose from for your DIY landscaping design projects. These elements are:

Water Garden
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Let's look at a few of the Architectural elements of landscaping:
Walls
Fencing
Hedges
Boundaries
Erosion Control