My backyard abuts a main road. Several times in the last few years, cars drove into my fence causing major damage to it. I asked the town to if I could install a guard rail, or place boulders in front of my fence for protection, they of course disallowed it, however, they suggested that I plant a row of trees to act as a natural guard rail. I need something fast growing that will grow to have a single straight thick trunk like Maple, Oak, Sycamore, etc, etc., but can be planted closely. I would consider planting thuja Green Giants, or other conifer, but I believe that they would have several trunks. I don't care if they are deciduous or coniferous evergreens. I checked several nurseries for Hybrid Poplar, but none sell them. In fact one nurseryman told me what a disaster Poplars can be. The reason I want to plant the trees is to act as a "natural guard rail"

trees are dug up.. when leafless.. when they are dormant ... but i do not know the proper timing for SC .. its either late fall.. early winter.. or late winter.. lol.. that narrows it down.. also.. will you be there to keep them PROPERLY WATERED???? if not.. the timing is IMPERATIVE ... for best success ... with this tree .. you could probably have 3 foot bare root whips mailed to the location rather cheap.. and at the proper planting time ... rather than driving hundreds of miles.. digging them.. transporting them.. torturing them.. etc ... what a nightmare for something that can mysteriously appear at your front door ... see link as an e.g. good luck ken ps: do NOT buy poplars .. tulip poplar is not a poplar .. its actually: Liriodendron tulipifera though fast growing.. poplars ... are fast to disease ... and fast to dropping huge limbs.. and fast to die ... and.. fast in tree terms.. is a decade or two ... but why plant future cost or problems .... Here is a link that might be useful: not that i am rec'ing this seller .. just size to price example ...

Our neighbors in town had a row of Arizona cypress. I don't know how they do in the wind out here, but they shot up fast and made a nice wall of shade for their RV. You have room for just about anything you want, so you can be a lot pickier. I have seen some huge sycamores and eucalytus, but I don't know how fast they grow . . . do you want something native? Do you want it blooming?

Most fast-growing trees are also short-lived trees, and many trees that have a reputation for fast growth really only grow fast at first, then slow down. For example, I have watched a row of trees planted in front of a local corner store for perhaps 25 years. The trees included a Red oak, a Pin Oak, and a Norway Maple. At first the maple did indeed grow faster than the others, but about 15 years ago the oaks caught up and now both the Red Oak and the Pin Oak are considerably larger than the maple I guess my point is that fast growing trees aren't always much faster growing than trees considered to be slow growing trees. I would plant a tree that will grow to be a nice adult tree rather than focus only on fast-growing trees.Nevertheless, some trees that tend to be fast include Silver Maple (grows fast but tends to be brittle. A very large tree), Eastern Sycamore (very large and impressive as an adult) and Eastern COttonwood (fast growing, not very often used as a street tree, although the similar Western Cottonwood is a popular street tree in much of the western US).