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Sunday - November 04, 2007

From: Lexington, TX
Region: Southwest
Topic: Wildflowers
Title: Soils for Central Texas wildflowers
Answered by: Barbara Medford

QUESTION:

Our family is moving to 40 acres near Lexington, TX with deep soil. Briefly talking to personnel at the Wildflower Center during Goblins in the Garden, I found that not all flowers in the Central Texas area will thrive/bloom in deep soil? Is it because of the caliche rocks? Or the depth of the soil? How can I find what plants will thrive in deep soil, as my girlfriend wants lots of flowers she grew up with to remind her of Austin. Thanks in advance ~~ David

ANSWER:

Not being familiar with Lexington, Texas, we did a little research and discovered it is only about 60 miles east of Austin, north of Giddings in Lee County. We will grant that is east of the Balcones Escarpment, which runs roughly up I-35W, and there is probably a lot less rock in the soil than there is in Austin and west into the Hill Country. However, depth of soil is not the only determinant of what plants will grow in a certain spot. There are also considerations about soil composition, sun exposure, moisture, drainage, climate, etc. Perhaps one outstanding point about the plants that grow in Travis County and the Hill Country is not that they only grow in that environment, but that they CAN grow in that environment. They have adapted to the shallow layer of soil over limestone, uncertain rain, and wide variations in temperature.

So, let's look at the conditions in the two different areas and then at considerations for growing some of the wildflowers so plentiful around Austin. In The Handbook of Texas Online, we find that there are three basic soil regions in Lee County, where Lexington is located. Lexington is in the extreme northern tip of Lee County, so we would assume that the soil there is of the type in northwest Lee County, which is light-colored, loamy or sandy soils over mottled or reddish clayey subsoils. The elevation in Lee County runs from 270 to 970 feet above sea level. Of course, there are many, many different types of soil in Texas, and you can go 50 feet and find two or more different soils, in strips or pockets. Going again to The Handbook of Texas Online, we find that Travis County has elevations from 400 to 1300 feet above sea level. It is divided by the Balcones Escarpment; the land west of the Escarpment is more arid than that to the east. The climate is considered sub-tropical and there is an average of 32 inches of yearly rainfall. The USDA Soil Map of Travis County cites approximately 10 different "groups" of soils. These groups have different proportions of soil components, but run fairly heavily to shallow, stony, loamy soils and very shallow, stony soils overlying limestone. Now you know why your shovel goes "clank" when you try to dig a hole in Austin.

Okay, now you probably know more about dirt than you ever wanted to. Let's look at some of the wildflowers that grow in the Austin area, and see what their favored soil environments are. First, we would suggest that you go to our How To Articles, where you will find excellent information on planting wildflowers and wildflower gardens. One of the things you will learn is that they are adapted to the rocky soils of this area with hard coats that can take the punishment of perhaps years of waiting for adequate moisture. But, with some preparation they'll be only too happy to grow in a richer, moister soil. After you've read the How To Article on bluebonnets, go to the Plant Database and type in "Lupinus texensis" in the Search Field. It will take you to a page with the basic information on locations where it is normally found, soils, etc. You can use this same search field, using the scientific or the common name, to look up whatever wildflowers you are particularly interested in, and shouldn't have any difficulty coming up with a good list of the "favorite" wildflowers from Austin.