Advice for the Home Gardener from the
Help Desk of the UC Master Gardener Program
of Contra Costa County
Subject: Best Tree for Fast Shade
Client's Request: I live in mid-County and am going to remove 9 dying Birch Trees due to beetles this fall. I need to plant a tree for shade in the afternoon and evening. I am debating between the Chinese Elm and the Raywood Ash. I am looking for a fast-growing shade tree so I would like a tree to be tall and have a large canopy. If you need to see a picture of my back yard please check Google Earth. Perhaps you have a better tree to suggest. I really do not want a very messy tree, if possible. Thank You,
Help Desk Response: Thank you for contacting the UC Master Gardener Program Help Desk concerning the replacement of your birch trees. You asked about Chinese Elm or Raywood Ash - both of these could likely fit your requirements for growth rate and shade, but they also have some considerations to consider as well.
The Raywood ash is a very attractive tree and sometimes does very well in our area, but in recent years many trees have been affected by dieback of branches. This is caused by a fungus which does not seem to kill the tree but can make it look quite unattractive.
http://ipm.ucanr.edu/PMG/GARDEN/PLANTS/DISEASES/ashdieback.html
The Chinese elm could also fit the bill, but can be somewhat messy from dry fruit litter.
https://selectree.calpoly.edu/tree-detail/ulmus-parvifolia
A few other suggestions you might consider, all of which have a reasonable growth rate include:
Common Hackberry (Celtis occidentalis)
https://selectree.calpoly.edu/tree-detail/celtis-occidentalis
One issue with this tree is that it is often attacked by an aphid which can cause messy drips from honeydew.
http://ipm.ucanr.edu/PMG/PESTNOTES/pn74111.html
Chinese Pistache (Pistacia chinensis)
http://sonomamg.ucanr.edu/Plant_of_the_Month/Chinese_Pistache/
Fruitless Mulberry (Morus alba)
https://ucanr.edu/sites/urbanhort/files/80182.pdf
This is the tree that is often pruned back to pollarded stubs that can look quite ugly to some in the winter. This is done to keep the tree small, but mulberries can also be pruned to retain good structure through normal growth.
I hope this helps in selecting your tree. For the long-term health of your new tree, it will be very important to select a good tree in the nursery, plant it properly and begin training the young tree for good structure. We do have some good information on these topics, so if you are interested please get back to us. You can also find this information on our UC website, http://cagardenweb.ucanr.edu/Landscape_Trees/
Help Desk of the UC Master Gardener Program of Contra Costa County (SMW)
Note: Contra Costa MG's Help Desk is available almost year-round to answer your gardening questions. Except for a few holidays (e.g., last 2 weeks December), we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 2380 Bisso Lane, Concord, CA 94520. We can also be reached via telephone: (925) 608-6683, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/. MGCC Blogs can be found at http://ccmg.ignore.edu/HortCoCo/ You can also subscribe to the Biog.