I live in Lafayette, La. Did you find an orange tree?
If not contact Saxon, Becnel & Sons in Belle Chase, La. Sorry - I do not have their phone number. They are one of the largest, most reputable growers in our region (that includes east Texas). They are a major supplier to big box stores and local nurseries. If you call them you will find that they are very helpful. They will advise you on variety (your best bet is a satsuma.) They can recommend a variety best suited to Houston.
You can probably find their trees at Lowe's or HD. The size will generally be 3 to 5 gallon. Get the 5 gallon if you can find it.
When buying from big box stores inspect the plants carefully. The grower ships perfect plants but the big box nurseries do nothing other than water - periodically. Inspect the underside of the leaves. Look for traces of leaf miners. Inspect the surface of the leaves for black sooty mold. Inspect the joint of the leaves to the stem. No white fluffy stuff in the leaf joints. Pull the plant out of the pot. It should not be root bound.
When planting keep this in mind - a 50 cent plant needs a $5 hole. No deeper than the root ball but 3 to 5 times wider. Plant now. Do not amend the soil. Do not fertilize until February 2018. You plant will try to produce a few oranges this year. Your best bet is to snip off the infant fruit. Let the root system develop and get established. Next year let the fruit develop. You will probably get 1 - 2 dozen oranges in 18. After that you can expect an increasing amount of fruit each year.
Fertilize with 8-8-8 in February and May/June. First year - Fill a 16 oz. peanut butter jar with 8-8-8 granulated fertilizer. Punch holes in the lid. With you left shoulder next to the branches and the shaker jar in your right hand circle the tree sprinkling fertilizer. Water well.
Citrus trees do not need to be fussed over. You will get leaf miners from moths and sooty mold from white flies. Neither will impact you fruit. Do check the leaves for what looks like bird poop. It is a Dog Faced Caterpillar. Do not spray. Just pick them off and squish them.
Cold weather - Temperatures in the upper 20's and low 30's will not damage your tree unless the temperature remains below freezing for more than 3 or 4 hours. Most winters you have no worries. Then you have the 2 - 4 days of low 20's that we had this year. In Lafayette we had 2 days with lows in the mid to low 20's. The temperature was below freezing for 8 to 10 hours each day.
Unfortunately we were out of town. My 5 year old Satsuma - which produced at least a gross of oranges - was severely damaged. IDK if it will survive. Had I been home I would have sprayed it with water just as the temperature fell below freezing. Ice forms on the leaves and branches and keeps them from getting below 32 degrees. A trick that commercial citrus growers use.
There I go again. I have been away from the site for awhile but many members know that I can get on a roll and just give TMI.
Good Luck with your orange tree.