Ask Mr. Smarty Plants

We are assuming that you are referring to Hibiscus coccineus (scarlet rosemallow), which is frequently sold in nurseries under the trade name Texas Star Hibiscus. The name is a little bit of a misnomer as the plant is not native to Texas, but to several southeastern states, including Louisiana. For more information on its general cultivation, see this Mississippi State University Office of Agricultural Communications article on Hibiscus coccineus, Texas Star Hibiscus.

However, that is all neither here nor there in regards to what is wrong with your plant. It would seem highly possible that it is suffering from transplant shock. The plant you purchased has probably been living under sheltered greenhouse conditions, mostly in shade, since it was first sprouted. It would be shock enough to suddenly enter the real world in your garden, but doing so in the middle of the summer would make anything wilt and turn yellow. Quick, get it out of the sun. It does need some sun every day, but get it in some shade for now. Then, trim off about 1/4 to 1/3 of the upper part of the plant (yes, including any flowers), but leave as many leaves as you can for plant nutrition. Don't fertilize, never fertilize any plant under stress. Water it, every day. Any plant in a pot outside in the summer, especially in the South, needs watering every day. The soil (and the pot) can heat up to temperatures that will simply cook the roots if you are not careful. Make sure the drainage in the pot is good, you don't want to drown it, either, but keep the soil moist. Give it some morning sun every day and in a few weeks, when it begins to perk up, you can give it a balanced fertilizer.

Oh, yes, and make sure all your neighbors know what plant you are growing, or you might get reported for growing marijuana!

Hibiscus coccineus

Hibiscus coccineus

Hibiscus coccineus

Hibiscus coccineus