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Be Nice to Your Trees

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Article and photo by Plant NOVA Trees
On a recent day, driving out of the sun into a wooded community resulted in a temperature drop from 91 to 86 degrees. We all try to stay in the shade in hot weather, competing for the parking spaces under trees. What we may not realize is that tree-lined neighborhoods are cooler not just because of the shade but because the trees themselves act as air conditioners. The basic concept is that it takes energy to turn a liquid into a gas – we see that when boiling water. When a tree sucks up water through its roots and releases it as a gas through its leaves, a process known as transpiration, the energy that causes the water to evaporate is absorbed from the surroundings in the form of heat, and the result is a lower air temperature. This principle of physics also explains why sweating cools our bodies.
Newly planted trees are particularly vulnerable to high heat, so the most basic care needed from us is to provide enough water until they are well established. Seedlings establish quickly, but a landscaper-sized tree needs several years for its root to grow out of the planting hole into the surrounding soil. Our torrential summer storms can fool us into thinking we are getting enough rain, but many of them are brief and don’t even budge the rain gauge. A young tree with brown leaves is a very sad sight. At the same time, overwatering any plant can be worse than underwatering, by depriving the roots of oxygen, so we need to be careful to follow instructions in that regard and allow the soil to dry out between waterings.
Once a native tree gets established, though, little if any care may be required for the next twenty years or so. Our oaks and other native trees evolved here and are accustomed to the local soils and our variable temperatures and rainfall, although those 91 degree days are adding to the stress of living in an urban or suburban environment. Because older trees may start to develop issues, it is wise to have those that are near houses inspected every two years by an independent consulting arborist, meaning one who has no financial incentive to sell tree care services. They can recommend procedures that may prevent a tree from becoming hazardous. Even better, they may be able to provide reassurance, for instance, that a tree that is leaning a little may be quite stable, despite the dire warnings of a marketing rep from a tree company that is eager to keep its crew busy. Always use the services of arborists certified by the ISA (International Society of Arboriculture.)
When future residents are facing temperatures even higher than today’s, a five degree lower temperature may make a life or death difference. Consider what hundred degree weather does to the human body when a prolonged blackout shuts down everyone’s air conditioning. It pays to take good care of our trees. Find out how on the Plant NOVA Trees website.

Beat the summer heat with a native plant shade garden

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Photo by Plant NOVA Natives

They say shade gardens are the gardens of the future, since it will be too hot to spend much time in the sun. That’s pretty much the case already on most summer days. Although sunny butterfly gardens still provide hours of entertainment, a shady place to relax or play in your yard is a welcome addition. An added bonus is that gardening is a lot easier in the shade, because the weeds grow much more slowly.
 
There are plenty of native flowers available to provide color in a shade garden. You can see examples of them on the shade garden page of the Plant NOVA Natives website. Many of those species also make excellent ground covers. For example, Woodland Phlox and Golden Ragwort are evergreen and spread to make a mat, with blue and yellow flowers respectively in the spring. April and May are a particularly lively time in the shade, as spring ephemerals such as Virginia Bluebell and Spring Beauty pop up and bloom before the trees and shrubs leaf out, then disappear when the shade gets too heavy. They make perfect companion plants for the ferns and sedges that provide a cooling backdrop all summer long. Contrasting foliage textures create visual interest even without flowers.
 
Why choose native plants? A plant is native to our environment if it evolved within the local food web and has the intricate relationship with animals and other plants that this implies. Plants such as turf grass and many of the ornamentals that were brought here after the arrival of the Europeans are nearly useless (and sometimes actually harmful) from an ecosystem perspective. Choosing native plants allows us to fit into the ecosystem instead of displacing it.
 
Most native plants can be planted any time of year that the ground is not frozen or saturated. Spring is of course the most popular time for gardening (though fall is even better.) As consumer interest has grown, conventional garden centers have been providing an ever-increasing variety of native plants. In Northern Virginia, 22 garden centers have red stickers on their native plants, placed there by Plant NOVA Natives volunteers, so all you have to do is walk down the aisles and look for the stickers. In addition, several local garden centers sell only native plants, which gives you the best selection of all.
 
In some cases, the first step toward creating a shade garden will be to create the shade. A glaring hot lawn is uninviting and can be remedied by simply planting native trees.  Since most trees require full sun to grow, an empty lawn is the perfect location for a grove of trees that will beautify your property while reducing air conditioning costs. Underplanting the trees with shrubs will provide homes and food for the birds.