Ask Mr. Smarty Plants

None of the above. Well, that is not absolutely true, however, as we do like compost worked into a hole, especially where there is clay soil, before a tree is planted in it.

However, all that other stuff sounds like you have been asking the same question of too many people, and taking each at his/her word. The whole point in planting a tree native not only to North America, but to the area in which it is to be grown, is that the tree's forbears will have adapted over millennia to growing in the soil, rainfall and climate they get, without reference to any outside additives.

In terms of faster growing, you need to realize that the speed with which any plant grows has much more to do with genetics than with any external influences. Fast-growing trees are not nearly as good an idea as you think they are. Most fast-growing trees will not live very long, and can be susceptible to insects and diseases more so than the ones growing at a more moderate pace.

So, we have three suggestions about planting the tree:

(1) Don't plant it until late Fall or Winter. No woody plant should be subjected to transplanting in the heat of Central Texas Summer, and don't purchase the tree until you are ready to plant it. 

(2) Be sure you are digging a big enough hole, so that a minimum of roots will have to be damaged in transplanting, and have the hole ready before you take the tree out of its nursery wrappings.

(3) Put some compost in the hole and mix it in with the native dirt. The tree will have to learn to put its roots out into the soil around it, but the compost will help with drainage (always a problem with clay soil) and also help the little rootlets access nutrients in the soil. 

We are going to suggest a few trees native to the area in and around Comal County. These will be moderate-growers and should do well for you. Follow each plant link to learn about projected size, light requirements and so forth. All of these include limestone-based or clay soils in their Growing Conditions section. We only listed one oak, Bur Oak, because while Comal County is definitely in the area for oak wilt, the Bur Oak is a white oak, much less susceptible to the fungus and rarely dies of oak wilt. 

Trees for Comal County, Texas:

Cercis canadensis var. texensis (Texas redbud)

Chilopsis linearis (desert willow)

Fraxinus texensis (Texas ash)

Quercus macrocarpa (bur oak)

Ulmus crassifolia (cedar elm)

Ungnadia speciosa (Mexican buckeye)

From our Native Plant Image Gallery:

Cercis canadensis var. texensis

Chilopsis linearis

Fraxinus texensis

Quercus macrocarpa

Ulmus crassifolia

Ungnadia speciosa