American elms are the dominant tree species on the National Mall. (All photos from Casey Trees)

Leaves and acorns of the Chestnut oak (Quercus montana).

Confused about what tree to plant? Here’s help.

These lists have been compiled by ISA certified arborists who work directly with our urban forest every day. They know trees. But more important, they know trees that will be happy in your front yard, under overhead utility wires, next to your sidewalk, and in the darkest corner of your backyard. Take a look, then head to a nursery for the right tree for your place, and start planting.

Fall is the best time to plant most trees: The soil is still warm and welcoming to roots; the air is generally cooler and the sun lower, which help prevent drying and scorching; and your young tree can get a great start on life if you water it weekly—unless there’s at least 1 inch of rain that week— until the ground freezes. In the spring, start watering weekly during the entire growing season, barring buckets of rain. Here’s a great guide to planting and subsequent tree care.

Leaf blades with an asymmetrical base and double-serrate margins are characteristics of elms.

Flowers of American elm.

Fruit of American elm.

American elm buds.

Arlington Forestry’s List of Suitable Trees

Alexandria Forestry’s List of Suitable Trees

Falls Church List of Suitable Trees (and much more!)

Casey Trees List of Urban Hardy Trees for D.C. and Environs (Form, leaf, bark, flower, fruit illustrated in color for each species. RiverSmart and other tree programs are only available to properties in the District of Columbia.)

If  you’ve compared these lists, you’ll notice that there are some conflicts. Err on the side of caution, particularly when it comes to invasive tree species. Just don’t plant these invasive and obnoxious trees!

Invasive plant species are detrimental in many ways. According to Arlington Forestry, invasive plants “negatively impact ecosystem health, green infrastructure and canopy coverage. Due to their ability to out-compete native plants, invasive plants have displaced many native species that provide habitat and forage for wildlife. Additionally, invasive plants can disrupt normal forest succession by inhibiting regeneration of native tree species.”

Wonder what trees work in the Big Apple? The lists are long, and to help prevent the spread of tree pests and disease, some species are forbidden in various boroughs. The list of trees suitable for tiny tree boxes along city streets may be worth a look for the idle curious. Click on the Small Trees tab for those and marvel at the stamina of these species to eke out a life in less than three feet of earth. Do not try that at home: Give your new trees plenty of space to spread their roots, which extend from two to three times the width of the canopy (the leafy top) in the best growing conditions.