Native Plants

Q. Who is Mr. Smarty Plants?
A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.
Did you know you can access the Native Plant Information Network with your web-enabled smartphone?
Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

rate this answer

Saturday - March 10, 2012
From: San Antonio, TX
Region: Southwest
Topic: Soils, Trees
Title: Tree to plant on rocky soil in San Antonio
Answered by: Barbara Medford
QUESTION:
I want to plant a tree in a particular spot in the yard but after digging down 10 inches I hit solid rock. I filled the hole with water and it took hours for it to go down. It is one of the higher elevations in the yard and a few feet away there is deeper soil (although the deeper soil is not a location I can plant a tree). It is not a spot that would get a lot of water unless I water it. If I build up the soil a little bit and dig a very wide hole and add decomposed granite would I be able to plant a bigtooth maple or texas ash tree there? (I know they both need good drainage but do well on rocky soil) If no, is there a tree you would suggest? I hope I have described the situation clearly enough that you could give me advice. Thank you.ANSWER:
Trees all over Central Texas, especially on the Edwards Plateau, grow in exactly those conditions. Sometimes the seeds (in wild areas) hit an area, germinate and grow a few feet and then die, because their roots have hit solid rock, or they have received insufficient rainfall, or something ate the plant down to oblivion. That is why every plant creates so many seeds, to guarantee that at least some of them live. But you don't want to garden like that on your own property; you want to put it in the ground and then see it grow up to be a fine old tree.
One thing that makes this possible is that most tree roots are within about 12" from the soil surface, to permit the exchange of gases and better access to moisture. In terms of water, any newly-planted tree, as well as other plants, will need an adequate regular source of moisture for at least the first year of its life. On our website we have lists of plants that grow dependably in various ecoregions of Texas, based on average annual moisture and soil types. We believe that the list from the Edwards Plateau is the best one to look at for your purposes. This is not to say that a plant on the list would absolutely thrive in your area or a plant not on the list would suffer; neither is true. Your chances of success are simply increased when you choose plants that have proved themselves hardy in the same area. Similarly, an adjacent ecoregion, such as the South Texas Plains could yield some good results. Follow each plant link to learn more about prospective height, bloom color and time, as well as soil types. We have checked every plant we selected to make sure it is native in or near Bexar County.
So, to your specific question. First, read our Step-by-Step article on How to Plant a Tree. We would only add to those instructions by agreeing with your suggestion of a wider hole, and also to build it up by working compost and possibly some decomposed granite into the native soil. We will go through both lists, selecting on "Tree" on Habit or General Appearance. When you look at the lists, you might choose other characteristics, such as dry soil or part shade that apply in your situation. While Fraxinus texensis (Texas ash) appears on the Edwards Plateau list, Acer grandidentatum (Big-toothed maple) appears on neither. Acer negundo (Ash-leaf maple) appears on the South Texas Plains list.
Recommended Trees from the Edwards Plateau ecoregion list:
Chilopsis linearis (Desert willow)
Cotinus obovatus (American smoke tree)
Diospyros texana (Texas persimmon)
Prunus mexicana (Mexican plum)
Ungnadia speciosa (Mexican buckeye)
Recommended Trees from the South Texas Plains ecoregion list:
Cornus drummondii (Roughleaf dogwood)
Zanthoxylum hirsutum (Texas hercules' club)
From the Image Gallery
More Trees Questions
Fast-growing medium-sized tree for New Jersey
July 06, 2013 - I'm looking for trees to put on a slight slope that will do well in rocky clay soil. I 'm in N.J. zone 6. The spot is full sun and would like a fast grower 50 ft high maximum. I'm replacing white p...
view the full question and answer
Huisaches in pots from Houston TX
May 20, 2012 - I have special (and probably weird) affinity to huisaches (acacia farnesiana). As a child I used to admire the three that elegantly guarded our backyard looking almost like fingers reaching for the s...
view the full question and answer
Evergreen trees for a Southern California yard
July 08, 2011 - Hello
I live in Irvine, CA and I am looking for a tree for our front yard. We recently planted oaks but they did not survive the clay soil. Our landscaper wants to replace them with oaks or with ...
view the full question and answer
Does Mexican plum require more than one plant for successful pollination?
May 25, 2011 - Re: Mexican plums.. Do I need to plant more than 1 to ensure proper pollination? I have always been told that commercial plums need at least 2 to pollinate properly for consistent plum production. A...
view the full question and answer
July 27, 2015 - Hi, thanks for all your help in the past! I have a generous spot in my spacious back yard that is begging to be filled. The top soil is 4" sandy loam, below which is black clay.With frog strangler r...
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |