Weekly Express-News Article

By Calvin R. Finch, PhD, SAWS Water Resources Director, and Horticulturist

Saturday, December 6, 2008

“Shrubs for the Landscape”

            The key to selecting the right shrub for your landscape is to select one with a final size that fits in the space that you have available for it.  That is final mature size, not size at the nursery.  All shrubs grow, and some grow quickly.  You usually want a shrub that will not grow to block the windows or the sidewalk.  It is also important that the shrub have the shade tolerance appropriate for the planting site.

 

            Hollies are the best overall shrubs in my opinion.  Most are evergreen, they are drought-tolerant once established, do not have pest or disease problems, and most can tolerate sun or shade. 

 

            Hollies are not instantly drought-tolerant.  It often takes two years for them to develop a good root system.  Until then, they must be watered at the base during drought periods.  The lawn sprinkler is usually not enough.

 

            Dwarf yaupon holly reaches about three feet tall on many San Antonio area sites, but up to five feet tall on better soils.  It is a disciplined slow growing shrub that makes a compact globe in sun or light shade.  It can be pruned, but usually does not need it.  Deer do not eat yaupon holly.  The leaves are blue-green and there are no thorns. 

 

            Dwarf Chinese holly is another good foundation plant.  It makes a flatter mound than dwarf yaupon and grows to about three feet tall and equally wide.  The leaves are shiny, Kelly green.  Dwarf yaupon holly does have a small sharp point on each leave.  The thorns are not savage enough to wound, but they are sharp enough to discourage youngsters from cutting through a planting.  The deer also pass up Dwarf Chinese holly in my neighborhood because of the prickly leaves.

 

            There are two versions of Burford holly that are worthy of consideration.  The standard Burford holly reaches eight feet tall and up to four feet in diameter.  The foliage is shiny and dark-green.  It makes an attractive dense upright shrub in sun or light shade.  Burford holly also has bright red berries in the winter that are very showy until they become cold softened and the birds eat them.

 

            The dwarf Burford holly only grows to about four feet tall.  It has smaller leaves than the standard version, but is just as tough and attractive.  Burford hollies have small sharp points on the leaves, but not enough to prevent the deer from eating at them in a drought.

 

            Pittosporum has lost favor as a landscape shrub.  In terms of the dwarf version, the negative feelings are deserved.  Dwarf pittosporum is attractive, but it is susceptible to a bacteria type disease that causes a dieback to most plants.  The standard pittosporum is a good choice, however, if you have the space for it.  I have one in my yard that is eight feet tall and 12 feet around.  The bloom every spring is attractive and fragrant.  Pittosporum tolerates sun or shade, and in my neighborhood, it is not eaten by the deer.  Like the hollies, pittosporum is evergreen and drought-tolerant.

 

            Nandinas are not everyone’s favorite shrub.  They have been identified as over utilized and even invasive in some areas.  Here is San Antonio the standard yaupon may reseed a few new plants or produce a few root sprouts, but invasive seems too strong a description for me. 

 

            The standard nandina, also called heavenly bamboo, reaches about seven feet tall.  It is upright and more open than a holly.  Although nandinas are evergreen, the standard nandina has great winter color if it is grown in the sun.  The berries are also very showy. Birds eventually eat nandina berries, but they are less sought after than holly berries.  Nandinas grown in the shade have less color and berries than sun grown specimen.  Nandinas are not a favorite deer food, but the leaves will be eaten during dry periods.     

 

            There is a size of nandina for every landscape need from groundcover up to the standard size.  Gulf Stream and similar selections have horizontal leaf arrangements that are very unusual.  Gulf Stream grows to three feet tall.

 

            Red tip photinias continue to be a favorite landscape shrub.  Unfortunately they usually only live four – seven years before the combination of chlorosis and an untreatable leaf spot makes them unattractive on most sites.

 

            I do not recommend that red tip photinias be used in our area, but if you simply must try them, they seem to do best on sites with deep well drained soils.  Photinias want to grow to 12 feet or taller.  The more you prune them and try to control size the quicker they decline.  Reduce stress on photinias by watering them once/month and by mulching three inches deep over the root system.  Photinias require full sun to prosper.

 

            Boxwoods tolerate both sun and shade and are not eaten by the deer.  They are the classic hedge plants that can be pruned to any shape that you desire.  In San Antonio, they do not perform as well as they do in moister, cooler, and more acidic situations.  On many local sites, they do not grow fast enough to tolerate shaping and they also suffer dieback.  The dieback seems to be related to many causes including cold and drought.