So what exactly is a low maintenance landscape?
The answer: A landscape that requires substantially less sweat equity and expense to maintain as opposed to the traditional landscape typified by large areas of grass, foundational shrubbery, and additions of seasonal colour driving a maintenance regimen of constant mowing, trimming, weeding, mulching and lots of water.
The ancillary part of the question is once you have created a low maintenance landscape, are you happy with the way it looks?
A result that achieves both objectives must be implemented with a design that addresses two fundamental questions:
What are the relevant functional needs that will expand the use/enjoyment of the proposed landscape area (i.e. seating area, paths/access, etc.), and what is the desired aesthetic
setting (i.e. Woodland Garden, English Cottage, Texas Hill Country, etc.).
The design is a filtering process to help in the selection and placement of plant species based on answering those two questions. Additional on-site factors such as sun/shade exposure, soil type, drainage, topography, etc.. will further help to narrow appropriate plant choices.
Other important factors that are often overlooked in achieving a low maintenance landscape and lower maintenance costs are plant compatibility and proportionality.
To ensure plant compatibility, it is critical to make certain that you are matching plant species (i.e. Red Yucca, Santolina, Black foot daisy) that share the same site conditions (full-sun, good drainage and minimal watering) to deliver a viable result.
If plantings consist of species with different environmental needs (i.e. watering), then you have put these plantings on a collision course. As an example, mixed plantings of Indian Hawthornes (high water need) with Mexican Feather Grass (low water need), and the inevitable result will be the demise of the Feather Grass leaving gaps in the landscape requiring replanting of these beds-an additional cost that could have been avoided.
Proportionality is understanding the mature size/width of a specific plant and if those growth factors will create future problems based on its proposed placement within the landscape. If so, then you are back to trimming/pruning in order to maintain it-a landscape of shrubs shaped into balls and squares. On a final note, one must consider the potential invasiveness of a plant species, either by roots or seeding out, and whether that will quickly overtake other plantings and initiate the unwanted maintenance of edging, spraying and hand pulling to maintain it, or eventually remove it (think Mexican Petunia) as the only solution.