Fall is a good time to select a fall color tree anyway, you can look for one that is coloring well.

Nyssa sylvatica (Black Gum) is a hardwood tree and is best chosen in early fall, when one can choose the best color change potential out of the available Black Gums for purchase.

These trees mostly are grown from seed and vary greatly in their fall leaf color change potentials.

Also, even if you want a large tree, do not purchase a bare root one. this tree does not tranplant very well if dug out of the ground not too long before it is to be sold and planted. It is best to select your tree from a range of 7 - 15 gallon sized, potted Black Gum trees. Just be certain to check the rootflare to make certain that non of those roots are circling the trunk. Before purchasing, you may need to push some of the potting soil away around the base of the trunk, inorder to see the root flair well enough to determine if the root flair is growing properly and not showing a tendency to circle the rootball or trunk of the tree.

Also just prior to planting, make two crossing, through each other, slices at the bottom of the rootball; That is if you see a solid mass of tangled roots there. Then along the sides, if you see roots crowded and entangled along or circling throughout the side portions of the rootball, simply make 4 slices cut from the top to bottom along the sides of the rootball, keeping all 4 cuts evenly spaced around the rootball, but not in line with the bottom of the rootball slices.