Planting trees
in Southern Arizona

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Trees are perhaps the most important plant selection you make in your landscape. Your choice will define how all other plants will be placed since it will determine where there will or will not be shade. Many poor choices are made due to a lack of understanding of the nature of the species selected, or a lack of foresight regarding what the plant will be like when it grows. We will help you make the right decision.


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Know your hardiness zone

It is important to learn the extremities of weather you can expect at your home. You may already be aware of the general weather at your home, but you may not have had a reason to pay particular attention to the low temperature, which usually occurs when you are just getting out of bed (unless you are a late riser). A general idea of how low your temperature is can be found online. But you can also invest in a high-low thermometer which will keep track. There are convenient digital thermometers that can monitor more than one location in your landscape (in dry climates, the cold air can sink into the low spots of your landscape and experiences a vastly different temperature than the higher parts). There are also cheaper, analog versions of such devices that are just as accurate and somewhat easier on the wallet. Once you determine your highs and lows, this can help you make informed decisions about what species you choose. If you are in the low desert, you may lean away from a bigtooth maple (Acer grandidentatum) since it is a species native to mountain canyons. If you live in the Sonoita grassland, growing a palo blanco (Mariosousa willardiana) is probably not the best choice as it is frost tender. Find out how much cold or heat a plant can take—we are working to profile as many native plants as possible on our website, but if you can’t find this information, contact us and we will help you.

Click here to find out your general hardiness zone.

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Know where you want sun and shade

Even in the lowest desert landscapes, you may not want to shade your entire yard. If you have a vegetable garden, casting too much shade on it will cause your tomatoes to fruit less than they could (or not at all). You may want to grow a butterfly garden—many of the best choices for butterflies require full sun. You may also want to utilize the shade of your tree on your house to help decrease your summer cooling bills.

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It is helpful to know that the sun tends to the south, especially in the winter. In the wintertime, the sun can be almost directly overhead. But the north side of any object (tree, house, etc) will be the shadiest side. The southern sides of objects will be the hottest and sunniest. You may have a wall on the south end of your property—the north side of it (your side) will be shady, especially in the winter. On the north end of your property, the south-facing wall will be like an oven in the summer, and still warm in the winter.

After considering how the sun moves over your landscape, then you may know where you want shade. You may want to shade a south-facing wall. You may want to block out the neighbor’s view into your private area. You may want to shade your home in the summer, but not in the winter. Whatever your needs are, you can then make educated decisions about what trees you plant. You could select a deciduous tree just to the south of your house so it shades it in the summer but lets the sun in during wintertime. You may choose a wide-canopied tree to block your neighbor’s view. You might want a series of short trees on that south wall to keep them from radiating heat back into your yard.

Know the nature of the tree you are selecting and apply it toward the needs of the landscape:

  • is it evergreen or deciduous?

  • how tall and wide does it get?

  • does it cast deep shade, or does it make for a bright, mottled sunlight.

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Consider the human needs of the landscape

You may want to consider the other needs of a landscape. Do you have a pool? You may not want to pick a tree that sheds a lot. Are there water pipes close to the planting spot? You may choose a tree that isn’t giant (and remember that the roots of a mature tree or shrub extend 1.5 to 4 times the width of the canopy). Are you here in the fall through the spring but leave in the summer? You wouldn’t want to choose a tree that flowers only in the summertime when you are gone. Do you have a lot of noise coming from your street? You can use trees and large shrubs to block the noise.

One important thing to consider—power and other utility lines. Often people plant trees below lines, not considering that when the plant gets large, the utility company may come along and top your beautiful tree. Make sure you place your trees such that when they reach their mature dimensions, they aren’t interfering with utility lines. It’s a heartbreaking thing to see a beautiful tree topped because it was planted in the wrong place. Similar tragedies occur when a tree or shrub is blocking a traffic sign.

In general, find out what the human needs are in the landscape, and when choosing your tree, make sure you aren’t creating conflicts and that the nature of the tree is serving you.

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Consider the wild things

We always ask that you consider the wild creatures when planning your landscape. As humans occupy more and more space in the world, and we have left less for the wild. Many of you want to do something to help but feel hopeless against the enormity of human destruction on the planet. But your backyard is literally the one place you can make a difference. We have become intimately aware of this, not only as people who run a plant nursery, but at our own home: when we first moved into our Menlo Park home in Tucson, the landscape was bare and we only had pigeons and house sparrows visiting the yard. Just a year later and we no longer had pigeons (they don’t like competition), and instead had a vast array of bird species visiting daily. To date we have observed over 50 species of birds. We also had hardly a butterfly in the yard before we planted out our landscape; now we have countless varieties, year round. The same is true for native bees, and a host of other fascinating native insects. Our yard is an eden for wildlife, and for us, since the things that wild creatures love are pretty much the same as what we enjoy: shade, flowers, and a variety of textures across the landscape.