Sissoo vs Ash for Landscapes

Q. We are considering planting Sissoo or Raywood Ash in our front patio which is covered with pavers. Are root problems a concern for Sissoo? I have concerns about dieback in Raywood ash because of diseases described in Northern California and Europe. Does our climate reduce the chances of disease problems? 

A. To me, the choice between Sissoo or Raywood ash is like picking between an apple and an orange; they don’t do the same job in the landscape. People choose Sissoo as a fast-growing personal shade tree while the Raywood ash is not fast-growing and is not much of a personal shade tree.

            Sissoo is much more likely to freeze during the winter here than Raywood ash. Because of their mature size, I don’t consider either one of them as good choices for a single-story residence in a desert climate.

            I observed a few Sissoo planted at homes in Las Vegas but most of what I know about this tree’s performance after planting is from homeowners in Arizona. The major complaints are its large size, limb breakage in strong winds, heaving of sidewalks and patios by its roots, general litter from leaves and fruit and root suckering throughout the landscape.

            Love it or hate it. There seems to be two opinions about this tree; people love it and others hate it. Not much in between. Homeowners who planted it in Las Vegas were surprised by its size and considered removing them after a few years.

            Raywood ash is not fast-growing like Sissoo but easily handles our winter temperatures without damage. But the trunk can be damaged by intense summer sunlight. It does not produce root suckers. Raywood ash is more “ornamental” with its beautiful fall color.

            Raywood ash is susceptible to a disorder, disease if you want to call it that, called Ash Decline. This disorder has been a problem in Las Vegas since the 1980s beginning with Modesto ash and later with Raywood ash. I generally don’t recommend planting ash trees susceptible to this disorder in the Las Vegas Valley.

            Both trees should not be planted in a desert landscape surrounded by rock. You’re asking for trouble if you do. Instead, plant them in lawns or surrounded by other plants that require moderate to high amounts of water.