Low desert gardens in USDA zones 9b and 10a can count on one thing – during the summer it’s going to be hot. But beyond this fact of life in Phoenix, there is actually a lot of variability from year to year. How early the heat starts, how long it lasts, how much monsoon rain we get, and how many winter frosts are all factors that can affect the survival of landscape plants. As an east valley landscape designer I can share my thought process about how to design a yard that is resilient no matter how the year turns out.
In my experience, the summer sun will make the difference between plants that survive and plants that fail suddenly during their first summer after planting, or fail after a few years in the ground. Every once in a while we have an intense summer that overwhelms the plants that were just barely hanging on during normal summers.
Erring on the Side of Caution
My approach is to avoid risk taking when compiling my plant lists. When I present a client with a list of plants I think will work best for an area, I’m thinking about many aspects such as size, bloom season, and style. The most important thing to consider might be the sun exposure though, because this will make or break the design. For example, I’m not going to risk putting a citrus tree in a place with lots of afternoon sun. The tree may hang on for a few years but it will be damaged by the end of every summer and there may be a particularly difficult summer that finally kills it. I’m always going to plant the citrus with shade and protection for a happier tree.
On the flip side, there are many desert native plants that love the sun. For those plants, I avoid any areas that might be too shady for them. I see this a lot – a long wall is planted entirely with bougainvillea or another sun loving plant, but one half of the wall is more shady and the bougainvilleas planted in the shade barely every bloom and they stay a fraction of the size of the full sun shrubs. In this situation it’s better to use two different plant species that are a similar size and complementary to each other.
Avoiding risk also means protecting frost sensitive plants by either planting them under trees, planting them in courtyards, or planting them with a plan to cover them during the winter if it gets exceptionally cold. It doesn’t get cold very often but when it does, the frost may damage sensitive plants within a few days.
Knowing Your Yard
The best way to be prepared is to understand your yard’s microclimates. Do you have a large open space that gets sun from sunrise to sunset? Or maybe your western wall gets burning hot every afternoon and you want to reduce the temperature. Large trees create dark shady areas that are much more protected than exposed gravel, and courtyards provide a break from wind and frost. Your yard may freeze more often than the metropolitan area if you live in North Scottsdale or out in Fountain Hills.
It’s good to know which parts of the yard are sunny and hot during the afternoon because these areas will need to be planted with the toughest plants. While it’s still summer, I recommend walking your yard between noon and 3pm and making a note of how hot the different areas of your yard are. Your gardener or a nursery associate will be able to help you choose suitable plants if you can identify specific areas of the yard to be planted and how sunny each area is.
Right Plant for the Right Place
In sustainable landscaping, horticulturists swear by the motto “the right plant for the right place”. A plant receiving the right amount of sun and irrigation will be able to shrug off a bad summer. A frost sensitive shrub planted in a protected spot won’t freeze. Proper planning and installation will result in a resilient, thriving desert garden.
Paige Maloney | Arizona Landscape Designer 
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