Native trees - General Principles
This page is a general overview of native tree planting and maintenance. For information about specific species,
see our page on Native Tree Choices.
For every landscaping need, there are Northern Virginia native trees that will fit the bill. If you only have time to do one thing to turn your yard into a wildlife sanctuary, let it be to plant a native tree.
The benefits of trees in general are obvious: in addition to improving property values and providing shade and year-round beauty, trees cool the environment, soak up greenhouse gases, and provide fruits and shelter for birds and other wildlife. But trees that are native to our area go far beyond that. Unlike those from other continents, a tree that is native to Virginia can support astonishing numbers of Virginia native insects. And insects—especially caterpillars—are what songbirds feed their babies. No native plants, no caterpillars; no caterpillars, no baby birds. And no butterflies either, of course!
A tree is the perfect way to honor or memorialize a person or event.
Details about growing conditions and wildlife value of individual species can be found in the Native Plants for Northern Virginia guide and app.
Eastern Redbud (Cercis canadensis)
Arlington's champion White Oak (Quercus alba)
Willow oak (Quercus phellos)
Choosing your tree – general considerations
For details and photos of individual species, see
A tree for every yard
A tree of any size will cool the air, sequester carbon and support wildlife. Small understory trees work in small yards or where there are overhead lines. Large canopy trees provide even more benefit if you have the space to plant them.
Spring blooms are the most prominent features of several understory trees.
Spectacular fall foliage can be reason enough to choose some trees.
Various bark textures provide winter interest.
Edible fruits are fun, though it may be a decade or more before the tree produces any. See the page on Edible Native Plants.
Trees have large, extensive root systems that reach beyond the canopy, so make sure you have room for them.
As with all plants, trees need to be given the right amount of sun and moisture to flourish, and some will tolerate salt or soil compaction better than others. Most require acid or neutral soil, but a few can tolerate alkaline. Check the pH of your soil - you can get an inexpensive pH meter at garden centers.
A deciduous shade tree on the west side of a building will significantly reduce air conditioning costs while allowing winter sun for warmth.
Plan around obstacles
In locations that might obstruct a view, choose a tree with one dominant leader so that the lower limbs can be removed if necessary as the tree grows.
Consider the overhead wires and clearance for cars and pedestrians.
Call Miss Utility first. And don’t plant a tree over your sewer pipes.
Avoid tree litter on walking surfaces
Trees with small leaves that shed over a long period are often preferred next to parking lots.
Acorns and other nuts may be problematic on sidewalks.
Choose the right size tree
Use small trees in small spaces. This may seem obvious, but you need to plan for the root spread and not just the height. Tree roots need 1 to 2 cubic feet of non-compacted soil volume for every square foot of expected crown area spread. This means that planting in a little square that is cut out of pavement is problematic except for the smallest trees. You'll need to choose in that situation between a small tree with a normal life expectancy of maybe 30 years, or a large tree that will also die after about 30 years after obtaining about the same height that an understory tree would have reached. As a strategy for greening some urban spaces, this may be the best you can do: you just plan to replace the trees periodically.
The shape is important as well. Some trees can be planted near walkways or streets, but others have branches that are too near the ground.
In a small space, you can also use large shrubs that have been arborized, meaning trained when young into a tree shape. Examples include Blackhaw Viburnum (Viburnum prunifolium) and Witch Hazel (Hamamelis virginiana), but any shrub that can tolerate light on its trunk could be trained this way. Some shrubs such as Staghorn Sumac (Ruhus typhina) and Common Elderberry (Sambucus canadensis) make nice small trees, but you would need to keep cutting back suckers.
Maximizing ecological benefits
The more plant species in an area, the more animal species will be supported and the less vulnerable the trees will be to diseases and pests.
The bigger the territory, the more species of insects, birds and other wildlife a natural area can support. You can expand the habitat value of nearby natural areas by planting the trees that grow there as a plant community. We are hoping to soon be able to provide you with plant lists to help you figure out the plant communities nearest you.
When plants reproduce sexually, meaning by producing flowers that get pollinated and go to seed, the offspring are unique individuals. Just as combinations of genetic traits result in differences between one human being and another, there are distinct differences between trees of the same species. Having a diversity of genetic traits provides resilience in the face of diseases, pests and changing climate. By contrast, cultivars are produced by cloning, which reduces biodiversity.
A tree that evolved in Florida or Oregon will not be as adapted to our region as another tree of the same species that evolved right here.
Plant a grove
The more trees, the better! Trees normally grow close to each other, with their roots interlocking, which provides stability. The best way to ensure that trees won't fall over is to plant them close together. Trees also communicate through an underground network, providing nutrients to each other and helping fend off attack from pests. If you have room, plant them in groves, spaced at 10 foot intervals. If that seems too close together, take a look at the woods - this is how they grow naturally, meshing their canopies and roots. Planting them all at once keeps them from shading each other out. This is also the best time to incorporate most shrubs into the grove.
Did you know?
94% of caterpillars that use trees as their food source complete their life cycle by falling to the ground and burrowing in the leaf litter over winter? If you remove that leaf litter, you are at least in part defeating one of the main reasons to plant native trees. How about planting a layered landscape instead?
Fringe tree (Chionanthus virginicus)
Oaks are the host plant to hundreds of caterpillars including the Red Spotted Purple butterfly. Caterpillars are the main food source for baby songbirds.
Because oaks hold onto their leaves in winter, many insects lay their eggs on them. When the larvae hatch in spring, Worm-eating Warblers and other songbirds descend on the leaves to feast.
Oak catkins attract wasps, caterpillars and aphids which in turn are a magnet for warblers.
Oak leaves of various species are the hosts for 150-200 species of leaf miners.
"Ask the Experts: Choosing and Planting Native Trees"
How to plant a tree
When to plant
Fall planting has many advantages, as the roots can to start to establish before the summer heat and droughts start. Spring planting is preferable for some slow-to-establish species, such as Baldcypress, American Hornbeam, Magnolia, Sweetgum, Tulip Tree, willows, and Willow Oak. Conifers prefer the warm soils of summer or early fall.
Choosing the specimens
Trees do not like to grow in pots. A seedling that is growing in your yard already and that is getting enough sun is the most likely to prosper. Otherwise, buy the youngest example you can find, as that tree within a few years will exceed in growth and health of a more expensive, larger tree planted at the same time.
Inspect the plant carefully. The top should be healthy with a good structure, and the trunk should be free of wounds (unwrap it to check), but the roots are the potential trouble-makers. Do not buy it if the roots are growing out the bottom holes. Probe the soil – there should be large roots coming out from the plant near the surface. Carefully remove it from the pot – garden centers should expect you to do this – and make sure the roots are white or tan and there are no large roots at the edge of the pot. If several trees in pots are sitting in a group, do not buy the ones on the edge that are receiving direct sunlight: sun heats up black plastic and kills roots.
Ask the garden center if the tree was produced by air pruning, a superior method which prevents the formation of encircling roots.
Prepare trees grown in containers by “squaring the ball:” cut off the surface roots from top to bottom on all sides. This works much better than splaying or scoring the surface.
Dig a hole that has twice the diameter as the roots. Make it just slightly deeper than the root ball, but mound up a little soil under where the root ball will go to form a little pedestal. Do not amend the soil! “Deglaze” the hole by roughing up the walls. Place the tree in the hole with the root crown exactly level with the surface. Fill the hole with water and let it drain. Replace half the soil, and water to settle the soil. Finish filling the hole and water again. Add a three foot in diameter ring of mulch, with 4 inches of green wood chips or 2 inches of wood - not bark - mulch. DO NOT pile mulch around the tree trunk – “mulch volcanoes” cause rot and can be home to mice and rats. Do not stake the tree unless absolutely necessary, and then only for one year at most.
For bare root seedlings, all you need to do is make the hole big enough to spread the roots.
The younger the tree, the easier the watering task.
Bare root seedlings: Add a gallon of water after planting. After that, no need to water unless we go over two weeks without rain.
1 inch diameter tree (measured 6 inches above the soil; typically an approximately 8 foot high tree): Give it one gallon daily for 4 weeks, then every other day for the rest of the growing season, then twice a week until established.
>1 inch diameter tree: One gallon per inch daily for 6 weeks then every other day until established.
(Watering is suspended once the leaves fall off, assuming normal rainfall.)
Water around the edge of the planting hole to encourage roots to reach for the water. Trees become established in 1 year for every 1 inch of tree caliper. In other words, a tree with a two inch trunk will take 2 years to establish! Saving on work is another good reason to buy smaller trees.
Deer will browse on most tree seedlings, which is why we see so few in the woods of Northern Virginia. You can protect them with a tree tube. Sink it an inch into the ground to also protect from voles. Tree tubes look opaque but let in enough light for photosynthesis.
Long term care - watch the roots
Avoid soil compaction
Compacted soil will seriously reduce tree growth.
Plant shrubs and groundcover under trees to dissuade pedestrians from walking over the roots (and to prevent accidents with lawnmowers and string trimmers).
Where compaction has already occurred – such as in a construction area now covered by lawn – many trees that naturally occur in swamps and along streams are often surprisingly good choices. The ability to grow in low-oxygen conditions makes them well adapted to dry, compacted soils.
Add a three foot in radius ring of mulch (do not let it touch the tree trunk.) Organic material gradually leads to soil loosening.
Don't disturb more than a third of the root zone, at the most. For a 10 inch diameter tree, don't disturb the soil closer than 20 feet from the trunk.
Don't drive machinery over tree roots.
Rule of thumb: don't cut roots that are wider than your thumb! This is especially true for Tulip trees, which do not compartmentalize well when the roots are cut, so fungal disease can spread right up through the tree.
Be very careful about gardening under trees, and if you are installing perennials, try to choose 2 inch plugs rather than quart pots.
Watch for shallow roots. Generally speaking, trees that are adapted to grow in bottomlands will have shallow roots. Examples include Red Maples and Sycamores, but there are many others - just look to see if the tree can be grown in wet conditions. (An exception is Hackberries, which grow in wet areas but have deep roots.) Interestingly, those wet-tolerant plants often grow quite well in dry, compacted soil, because it is not that their roots like water so much as that they can tolerate low oxygen conditions.
Never pile more soil on top of the ground over tree roots within the drip line. If you feel a need to mulch, use wood chip mulch, which will allow air to reach the ground, no more than 2-4 inches deep, and not near the base of the tree.
Victim of a mulch volcano
The Tree Benefit Calculator, developed by Casey Trees, allows anyone to make a simple estimation of the benefits individual street-side trees provide. With inputs of location, species and tree size, users will get an understanding of the environmental and economic value trees provide on an annual basis.