I am frequently asked, "What's the best shade tree I can plant?"
Unfortunately, there's really not one "silver bullet" answer.
There are roughly a dozen trees I believe fall into the category of the "best tree to plant." All but the live oak are deciduous, meaning they lose their leaves in the winter. While live oaks are also great trees to plant in Gulf Coast landscapes, they are notoriously slow growers.
The other twelve trees meet three very important requirements. They GROW FAST, provide AMPLE SHADE and are ACCLIMATED TO OUR SOILS. Note that in the list below, each tree is accompanied by its botanical name. It is important to confirm the botanical name when buying any of these trees, because often they can be generically labeled. For example, many times an Arizona ash is just labeled as an "ash." I would strongly recommend avoiding such trees.
Green Ash (Fraxinus Pennsylvanica)
Be careful here. The old saying "ash is trash" holds true for the Arizona ash, but the green ash is anything but. The Arizona ash is not recommended because of its short life span — roughly 20 years. Every green ash I've planted has been a stunning success. It can normally reach 50-60 feet at maturity and excels in all three of the provisions. In fact, I planted a one-foot sapling six years ago, and it's already 20 feet tall. Most green ashes at nurseries and garden centers will already be much taller. The down side to the green ash, is that it's usually the last of all trees to leaf out in the spring.
White Ash (Fraxinus Americana)
The white ash (often called the Texas ash) grows even faster than the green ash. It can reach 70-75 feet at maturity, and like the green ash, it's not susceptible to many diseases or insect pressures. However, because of its rapid growth rate, it can often shoot straight up and not provide the canopy we desire in a shade tree until it is many years old. On the plus side, the white ash/Texas ash also provides some stunning color in the fall if we get cooler temperatures. It may not, however, be readily available at local nurseries.
Shumard Red Oak (Quercus Shumardii)
The Shumard is one of the most popular landscape trees among professional landscapers in Texas. It can grow rapidly, possibly 50-60 feet at maturity, and will have a spread of possibly 40 feet at maturity. Its popularity is also driven by some wonderful autumn color. Quite possibly, the Shumard's biggest selling point could be its easy adaptability to our alkaline soils. On the down side, like the green ash, the Shumard can often be one of the last to re-leaf in the spring.
Nutall Oak (Quercus Nuttalli)
Similar to the Shumard in many ways, the Nutall has excellent fall color. For the botanically savvy, one sure way to tell the difference between the Shumard and the Nutall is the Nutall's over-sized acorns with their unique stripe. The Nutall (often labeled a swamp red oak) also likes the clay soils of the Gulf coast. On the down side, it can often be mislabeled and is not as readily available as the Shumard.
Overcup Oak (Quercus Lyrata)
This oak is not common at garden centers, but it is catching on in popularity among landscapers. I really like the overcup because of its upswept branches. That translates into the need for little, if any, pruning. It will not grow as tall as the previously mentioned oaks — normally, it matures at about 40 feet.
Mexican Oak (Quercus Polymorphas)
The Mexican oak used to be more readily available, but it has fallen out of popularity. It can reach 70-80 feet at maturity in Texas, but is known to reach 100 feet in Mexico. Hard freezes (single-digit temperatures) in the winter could kill a Mexican oak.
Mexican Sycamore (Plantanus Mexicanus)
First, it's all about raking leaves. Sycamores, in general, produce an enormous leaf-drop. But most other Sycamores just don't do as well along the Gulf Coast as the Mexican Sycamore. It can reach 100 feet tall very easily, and I've seen many just under 10 years old that are already 50-60 feet tall. The best selling point for this specimen would have to be the unique silver coloring on the under side of the leaves. For those who desire silver leaf maples (one of the worst trees we can plant here), the Mexican Sycamore makes a superior alternative - if you can put up with the falling leaves.
Cedar Elm (Ulmus Crassifolia)
This is a tough son-of-a-gun, and that makes it perfect for Texas. While the cedar elm is known to mature at 70 feet, this Texas native's span is often only 30-35 feet and not very dense. But it not only puts up with stresses like wet feet, drought and pollution, it is also considered a lot more structurally stable than many other elm trees.
Winged Elm/Corky Winged Elm (Ulmus Alata)
You can't miss this one, because of its unique bark. While it will grow fast, it matures at only 35-40 feet. The corky winged elm gets its name from the gnarled bark on its trunk and limbs. Like all elms it has early leaf-drop and a not-so-dense canopy.
White Oak (Quercus Alba)
The white oak, if planted properly, can be a huge tree. In many cases, they are 75-80 feet tall at maturity. It doesn't grow as fast as the other oaks mentioned, however — it can take 20-30 years to reach that awesome potential height. This is also a tree that needs to be planted all alone because it not only grows tall, its span can often reach 60-75 feet.
Bradford Pear (Pyrus Calleyranna)
While this tree won't get huge, a few of them planted together can make a great "barrier." The leaf growth is dense, but they will only reach 30 feet at maturity. The worst aspect of the Bradford pear is its susceptibility to fire blight. The disease usually won't kill a Bradford, but it can defoliate the tree at the worst time of the year — when you really need the shade. On the plus side, everyone loves the Bradford when its beautiful canopy blooms with striking white flowers early in the spring.
Drummond Red Maple (Acer Rubrum)
The most common maple is the silver leaf maple, which should not be planted here. The Drummond, however, can live in this climate, and it produces gorgeous autumn color if cool temperatures hit at just the right time of year. They can get fairly tall, with many reaching 60-70 feet at maturity. And, like most maples, they have big leaves you'll have to deal with in the fall. The Drummond can also be found locally as The Woodlands red maple.
Laurel Oak (Quercus Laurifolia)
Although technically a deciduous tree, in most parts of South Texas the laurel oak sheds its leaves for new ones (much like a live oak) in early spring, which is also why it is mistaken for a live oak. The plusses for a laurel oak are its adaptability to our soils, its quick-growth and its dense canopy, making it a perfect "shade tree." On the minus side, it produces lots of acorns, and its canopy is so dense that it will be difficult to grow grass under it in future years. If you're looking for a great food source for wildlife, however, that propensity for acorn production makes it a good choice. Newly planted laurel oaks occasionally have a problem with freeze damage, but once established they're likely to withstand normal Houston-area winters. And make sure you actually select a Quercus Laurifolia -- if the label doesn't have that Latin name, it likely isn't a true laurel oak.