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Growing Azaleas in Arizona

azalea image by Igor Zhorov from

Azaleas (Rhododendron spp.) typically bloom flowers every spring in a variety of colors, such as pink, white, purple or red. Arizona consists of United States Department of Agriculture plant hardiness zones 5 to 10, which have average winter low temperatures from minus 20 degrees to plus 35 degrees Fahrenheit. This vast difference in climates makes choosing the right azalea essential if you want it to thrive. Fortunately, there are many azalea varieties and they differ in plant hardiness, usually ranging from zone 4 to 9, making most of Arizona a suitable climate to grow azaleas. Once a variety is chosen, most azaleas are planted in a similar manner.

Select a planting location that receives morning sun and afternoon shade. Do not plant near sunny sidewalks and driveways, or near west-facing walls because the heat emitted from these surfaces is more likely to cause the azaleas to dry out during the summer months, especially in the hotter zones of Arizona. In addition, do not plant under trees since trees and the azaleas will compete for the same water and nutrients. Avoid planting in areas where water tends to puddle, such as near a downspout.

Test the soil’s pH level and adjust the levels. Take a soil sample to your local county extension office to be tested or purchase pH soil testing strips at your local nursery. Ideally, the soil should have a pH level between 4.5 and 6.0. Based on the results, if necessary, adjust the pH level by adding sulfur to lower the acidic level or lime to raise it. Dosing will be based on your initial results, so follow the dosing instructions on the label.

Dig a hole that is the same depth, but two to three times as wide as the plant’s container. Plant multiple azaleas to accommodate their full mature width, which differs among varieties.

Mix in organic matter, such as compost or leaf mold, to the soil you just dug out until the new soil is composed of one-third to one-half organic matter. Then, fill the hole back in, packing it down lightly as you go.

Water the azalea before planting it and take it out of its container. Tapping on the sides with a hammer can sometimes help get it out. If the roots are circling the soil, take a knife and cut four even vertical slits that are 2 inches deep and then loosen the roots with your hands.

Plant your azalea in the center of the amended soil. Dig a hole deep enough so that the top of the root ball when planted is 1 inch above ground level. However, some Arizona soils have high amounts of clay particles. If your soil is normally high in clay, then dig a hole so that the top of the root ball is 2 to 4 inches above ground level when planted.

Back fill the amended soil to fill in around the root ball and pack it down lightly. Form a gradual slope from the top of the root ball to the outside perimeter of the original hole you dug out in step 3.

Water the azalea with 2 to 3 inches of water and then lay 4 inches of organic mulch, such as bark, wood chips, pine straw or shredded leaves. This will help maintain water and help the soil from baking, especially in the hotter Arizona zones. Mulch also keeps the soil warmer during the winter in the cooler zones. Mulch should be sloped like the soil to help with water drainage.

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