As we will soon (hopefully) see the end of the extreme summer heat, it is time to think about planting. As a transplant from the North, a big struggle I had when I started growing in South Texas was how different gardening was do here. Up North you are a good gardener if you have tomatoes by the 4th of July, down here you are great if you still have tomatoes in June. But perhaps the more challenging issue was planting.
Most magazines and catalogs along with many books talk about spring planting. Spring in South Texas lasts about 2 weeks, hardly enough time for plants to get established and ready to deal with strong SE winds for days on end and the ever climbing temperatures. And many if not most of what we are planting in our yards are evergreen plants so they really do not have a dormant time.
So when is the best time to plant in South Texas? August and September. The plants are still in active growth mode, the temperatures are starting to cool a bit and there generally is not a wind issue. The plants can get established before the cooler winter temperatures and then face our spring into summer with an established root system that can take advantage of every drop of spring showers and not be blown over by our spring breeze. Later in the fall may not give the plants enough time to grow before the soil cools down. Cold fronts generally begin by November and then we have things like our snow last December.
Fall is also our best time of the year for rain and having plants ready to take advantage of those fall showers helps to get those roots down and the leaves out. Then in the "spring" your plants will be ready to give you a great show (-especially if you feed them properly).
So YES you can and should be planting in the heat to give your tropicals and subtropicals the best start. Be making your garden plans now and don't forget to think about where a shade tree might make next summer just a little bit more comfortable.