Arizona Ash (Fraxinus velutina) are quite common in Arizona and are well adapted to the sunny climate here. In fact, many other types of ash trees grow in Arizona as well. There are more than 65 species of ash trees. Wikipedia lists many ash trees based on the regions where they are found. Note that there are other woody plants that have “ash” in their name (such as mountain ash and prickly ash), but they are not of the genus Fraxinus, so they are not varieties of ash at all. Below is a list of some of the Arizona ash varieties, which is by no means exhaustive:

• green ash (Fraxinus pennsylvanica) – also called ‘swamp ash’ or ‘water ash’
• Raywood Ash (Fraxinus oxycarpa)
• Ash Shammel, (Fraxinus uhdei) – also called ‘tropical ash’
• Fantex Ash, (Fraxinus velutina) – also called ‘Rio Grande Ash’
• small leaf ash (Fraxinus greggii)
• Arizona Ash (Fraxinus velutinalisten)) – commonly known as ‘velvet ash’ or ‘modest ash’
• single leaf ash (anomalous fraxinus)
• good ash (Fraxinus gooddingii)
• Fragrant Ash (Fraxinus cuspidata)
• chihuahua ash (Fraxinus papilosa)

The Arizona ash has many positive characteristics, but along with them come some disadvantages. Horticulturist Calvin R. Finch, Ph.D., has called the Arizona ash a ‘garbage tree’ due to its lifespan of only 25 to 30 years, among other reasons.

Ash trees are deciduous, meaning they lose their leaves at the end of the growing season. Many types of trees are considered untidy, and the ash is no exception. Fortunately, most ash trees limit their leaf drop to a period of two weeks. Most ash trees also produce seedlings, either year-round or just once a year, but in large numbers depending on their genus and species. With an ash tree, you should learn to enjoy raking at least once in a while if you prefer a tidy garden.

Most ash species are fast-growing trees. While rapid growth makes for quick shade, it also comes with drawbacks. Fast-growing trees tend to develop shallow roots. Although the roots of ash trees often grow near the surface, they generally tolerate alkaline, rocky soils. However, as Watson and Gilman describe in their green ash fact sheet, these shallow roots can “become a nuisance.” as they pull up curbs, sidewalks, and make grass mowing difficult.” Finch is quick to point out another downside to the rapid growth typical of most ash trees: “Unless you prune it regularly, it can become a tangled mess with dieback. “frequent branching.” Plan to prune ash trees at least every few years to promote healthy branch structure and prevent their canopy from becoming too dense. Otherwise, there may be weak growth that is prone to snapping. It is a good idea to allow multiple trunks, as this will eventually lead to structural failure. It is best to establish a central trunk while the tree is still young. Before planting a new ash tree, make sure your garden is large enough. Ash trees are large trees.While most mature ash trees reach 40 to 50 feet tall, some can be over 80 feet tall and all tend to have a full canopy and round.

Arizona ash trees, like many other plants, are susceptible to various pests and diseases. These include cankers, fungus and various fungal infections, leaf scorch, rust diseases, and pests such as spider mites, webworms, carpenter worms, and borers. Ash trees are particularly vulnerable to Verticillium wilt, which is a soil-borne fungus. In some parts of the country (mainly the Midwest), the emerald ash borer has killed many tens of thousands of ash trees. Fortunately, Arizona ash tree varieties have not yet been affected by the destructive emerald ash borer (read more about this pest at http://www.emeraldashborer.info). Trees that withstand poor environmental conditions are more vulnerable to these problems, so it is important to keep the tree’s defenses up by properly watering and fertilizing.

In your effort to maintain your Arizona ash, I encourage you to research by species, because there is an amazing variety of unique qualities attributed to each. There is a series of several hundred fact sheets on tree and shrub species, written by Edward F. Gilman and Dennis G. Watson, both professors at the University of Florida. These are a good source of background information on the specific trees you may want to learn more about. They are provided in part by the Forest Service and the United States Department of Agriculture.

If kept well, ash trees are very lush and beautiful. On the other hand, ash trees that are not easily cared for become an eyesore and are much more likely to play host to various tree pests and diseases. While certain varieties of ash are fairly drought resistant, most require a lot of water. Flood irrigation will provide the best environment for an ash tree. If your garden is not irrigated, it is best to mimic flood irrigation with the garden hose by watering deeply once or twice a month. If you live in Arizona and have an ash tree in your yard that you’re hoping to keep healthy and looking great, prepare to cringe when you see your monthly water bill. You may also want to fertilize your ash trees regularly. Mulching around the tree is also beneficial for two reasons: not only will it enrich the soil as organic matter breaks down, but the mulch will also retain moisture from irrigation to keep the soil moist longer.

Although they are not especially easy to care for, it is well worth the effort to keep every ash tree in your garden healthy. In exchange for your service, they will provide you with lots of lovely shade. A healthy Arizona ash is sure to enhance the beauty of your garden.