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Saturday - October 02, 2010

From: San Antonio, TX
Region: Southwest
Topic: Shade Tolerant, Grasses or Grass-like, Herbs/Forbs
Title: Plants for narrow planter boxes in San Antonio
Answered by: Barbara Medford


We have a narrow flower planter box in three sections above a french drain in front of our house. The box is about 2 feet high (filled with Gardenville soil) above a french drain covered with filter fabric. We have about 25 linear feet in length (by 8-12 inches wide) in dappled shade, 12 linear feet in length (by 22 inches wide) in shade and 13 linear feet in length(by 20 inches wide)in bright sunshine area. What native wildflowers and other native plants would you recommend for each of the three sections of the flower box planter? It would be okay if some of the plants were to hang over the front edge of the planter. Also, the shaded area (12 foot section) has a high rock wall behind it and could accommodate taller plants. The other two areas have windows a couple of feet above the flower box and would need shorter plants (less than two feet tall if possible). Thanks for your recommendations.


If you don't mind our using technical terms, this question is a doozy! Since we can't see the area in question, and are not prescient about what gardeners want in terms of color and so forth, we are going to teach you how to use our Native Plant Database to find exactly the right plants for YOU. We will walk you through one plant for one area that we would recommend, and then give you a couple of recommendations for each of your other areas. You can go to the links for each plant to learn the culture of that plant, how much moisture, sun or shade, and the expected size of that plant. Any plant we recommend will not only be native to North America but to the San Antonio area.

The first step is to analyze what are the different conditions, and what will be the growing requirements for each? If we understand you correctly, you have these situations:

1. 25 ft. x 1 ft. dappled shade or part shade (2 to 6 hours of sun a day); plants less than 2 ft. tall

2. 12 ft. x 22 in. in shade (less than 2 hours of sun a day) wall behind it, can take taller plants

3. 13 ft. x 20 in. in full sun (6 or more hours of sun a day) plants less than 2 ft. tall

So, where to start? Why, at the very beginning, of course, with Situation No. 1. Our first observation is that 12 in. is not very much room for roots, especially of woody plants. You will probably not be able to plant any shrubs in that space, and they would likely be too tall anyway. We would suggest either perennial herbaceous plants or some low decorative native grasses or grass-like plants that can stay that short.

Go to Recommended Species. Select Central Texas on the map. In the sidebar on the right side, select "herb" (herbaceous blooming plant) under General Appearance, "part shade" under Light Requirements, and "perennial" under duration, and then click on NARROW YOUR SEARCH. This gave us a list of 27 plants native to this area and fitting your specifications. We selected one, Coreopsis lanceolata (Lanceleaf coreopsis), after noting its expected height was 0 to 1 ft., it needed part shade, is evergreen and blooms yellow from April to June.

Next, you mentioned planting some wildflowers. Many wildflowers are annuals, and will disappear a good part of the year, but if you time your seeding (they should usually be seeded about NOW, in October), they can come up, bloom, set seed and reseed themselves, before some of your perennials get going in the Spring. So, we used the same selection, only using "annual" under Duration. This yielded 11 possibilities, and we chose Phlox drummondii (Annual phlox) as an example. It is an annual, grows in part shade, grows 6 to 12"  and blooms white, pink, red and purple from March to June.

Finally, for this space, we wanted to look at some native grasses or grass-like plants. We used the same methods, but checked on "Grasses and grass-like plants" under General Appearance., this gave us 9 plants from which to choose. We selected Nolina texana (Texas sacahuista) which is perennial, evergreen, 1-1/2 to 2 1/2 ft. tall, and blooms white or green from April to July.

By now, you should be able to take over and choose whatever you like, however you like it, from our Native Plant Database. As promised, we will list some suggestions for the other two planting areas.

Situation 2: 12' X 22", shade, can take taller plants:

Lobelia cardinalis (Cardinal flower) - perennial, blooms red May to October, 1-6 ft. tall

Rudbeckia hirta (Black-eyed susan) - annual, 1-3 ft. tall, blooms yellow June to October, can grow in sun, part shade or shade

Chasmanthium latifolium (Inland sea oats) - perennial grass, grows 2 to 4 ft. tall.

Situation 3: 13 ft. x 20 in., sun, less than 2 ft. tall:

Melampodium leucanthum (Blackfoot daisy) - perennial, 1-3 ft. tall, blooms white, yellow March to November, sun

Machaeranthera tanacetifolia (Tahoka daisy)  - annual, 1-3 ft. tall, blooms purple May to October.

From our Native Plant Image Gallery:

Coreopsis lanceolata

Phlox drummondii

Nolina texana

Lobelia cardinalis

Rudbeckia hirta

Chasmanthium latifolium

Melampodium leucanthum

Machaeranthera tanacetifolia





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