Ask Mr. Smarty Plants

Before we select some plants, we want to warn you that most oaks are allelopathic, in that they emit substances to discourage competition from other plants beneath them. The first thing we need to do is to try and identify which oak tree species we are talking about. When we searched on "Spanish Oak" in our Native Plant Database, we got three separate species of oaks, all of which include the name "Spanish Oak" as one of their common names. These three are: Quercus buckleyi (Buckley oak), which the USDA Plant Profile indicates is native to the Austin area;  Quercus falcata (southern red oak), mostly native to East Texas, and Quercus texana (Texas red oak), which only grows in a few counties in Texas, again according to the USDA Plant Profile. All three, of course, are related in terms of being members of the Quercus genus, and all three are considered red oaks. No doubt the retailer who originally sold the tree called it a "Spanish Oak" because that sounded more romantic or perhaps was a better seller.

We will choose to deal with the Quercus buckleyi (Buckley oak), since it is native to the Austin area. We would just like to mention that the red oak is very susceptible to Oak Wilt, which has decimated many valuable trees in Central Texas, and urge you to read this page from the Texas Oak Wilt Partnership (of which the Lady Bird Johnson Wildflower Center is a member) on How to Identify and Manage Oak Wilt in Texas. This includes not pruning unless absolutely necessary from January to June when the nitulidid beetle, which spreads the fungus, is active and avoiding damage to bark and branches year-round. 

We are going to look at shrubs and possibly some ferns that are native to the Austin area and tolerate shade. Hopefully, these will prove able to survive in spite of the allelopathic abilities of the oak trees, but we make no guarantee. If you find that nothing will flourish there, perhaps you would be happier with a nice area of mulch for your sitting area. 

Shrubs for Shade in Austin:

Callicarpa americana (American beautyberry) - 3-5 ft. tall, deciduous, blooms white, pink May to July, purplish pink berries in Fall and Winter, low water use, part shade

Malvaviscus arboreus var. drummondii (wax mallow) - 3-6 ft., deciduous, blooms white, red May to November, medium water use, part shade or shade

Salvia regla (mountain sage) - 3-5 ft., deciduous, blooms red July to October, low water use, part shade or shade

Senna lindheimeriana (velvet leaf senna) - 3-6 ft., deciduous, blooms yellow August to October, low water use, sun or part shade

Ferns for Shade in Austin:

Adiantum capillus-veneris (common maidenhair) - 6" to 1 ft., evergreen, medium water use, part shade or shade

Athyrium filix-femina ssp. asplenioides (asplenium ladyfern) - 3 to 6 ft., deciduous, medium water use, part shade

Dryopteris ludoviciana (southern woodfern) - 4 ft., part shade or shade

Osmunda cinnamomea (cinnamon fern) - 1 to 3 ft., deciduous, sun, part shade or shade

From our Native Plant Image Gallery:

Callicarpa americana

Malvaviscus arboreus var. drummondii

Salvia regla

Senna lindheimeriana

Adiantum capillus-veneris

Athyrium filix-femina ssp. asplenioides

Dryopteris ludoviciana

Osmunda cinnamomea