Planting-site check

How the verdict is made

• Hardiness zone. Inside the zones the species is known to take is good. One zone colder or warmer is a struggle, and two or more is a fail.
• Sun and soil. Each answer is compared with the light and the soil moisture the species takes in cultivation. A tree or shrub tagged as tolerating shade, wet soil or drought fits that answer, here as in the finder and the shop. One step off, such as part shade for a full-sun tree, is a struggle: it lives but grows slowly or needs help. Two steps off is a fail.
• What the answers mean. Full sun is 6 or more hours of direct sun, part shade 3 to 6 hours or dappled light all day, and shade under 3 hours. Dry ground dries within a day, average ground drains in a day or two, and wet ground stays damp and puddles after rain.
• How far from power lines. Closer than 15 feet to distribution wires, a tree should mature at 20 feet or under. From 15 to 50 feet out, it should mature at 40 feet or under. From 50 feet out, any tree goes.
• How far from a house. A tree or shrub stands at least the distance its own page gives from a wall. Where the page gives none, or the species is one we do not grow, the check takes half the mature crown, and never less than 15 feet for a tree.
• Struggle, not fail. Wires and walls can make a tree or shrub struggle but never fail, since they mean pruning rather than death.

The wire zones are the International Society of Arboriculture's, from its brochure Avoiding Tree & Utility Conflicts (2021). "The low zone extends 15 feet (4.5 meters) on either side of distribution wires", and a tree there "should have a mature height of 20 feet (6 meters) or lower". "The medium zone extends between 15 and 50 feet (4.5 and 15 meters) from distribution lines", for a tree "with a potential mature height of 40 feet (12 meters) or lower". "The tall zone is at least 50 feet (15 meters) away from distribution lines." A spot exactly 15 feet out counts as the medium zone, as on the plant pages that say to plant a tree 15 feet from overhead wires. The wall rule is the University of Maryland Extension's, from Planting Trees in Our Changing Climate: "Plant small trees a minimum of 15’ away from the foundation", or half the mature canopy. The same page allows a taller tree under wires: "Choose trees that are 25’ tall or lower at maturity." The check follows the stricter ISA figure of 20 feet. Each species' zones, light and soil moisture are those shown on its own page. Native street trees covers the strip and the wires, and Small native trees and large shrubs for a small yard covers placing a tree near a house.

What this cannot see: soil pH, salt, wind, compaction, drainage below the surface, and the difference between a healthy young tree and a stressed one. A wet answer for a spot that only puddles in spring is too harsh, and a full-sun answer for a spot shaded by a house after two in the afternoon is too generous. When in doubt, run University of Maryland Extension's drainage test: dig a hole 12 inches deep and about 12 inches across, fill it with water, and the next day fill it again. All of the water should drain out within eight hours. More than 4 inches an hour means the ground is probably very sandy, and less than an inch an hour is too slow. For a spot that gets road salt or salt spray, start from the trees and shrubs labelled Salt tolerant.

The address carries the planting-site check's inputs, so a link opens it filled in, and Copy link on a result writes one: species (a plant's slug, the last part of its page's address, such as white-oak, or the id of a native we do not grow from its reference list), zone (a whole number from 2 to 10), sun (full, part or shade), moisture (dry, average or wet), distance (the feet from a house or wall, 0 to 200), line (the feet from overhead wires, 0 to 500), sort (featured, name, price-asc, price-desc, height, hardy or fast, for the better fits). For example, /tools/site-check/?species=white-oak&zone=6&sun=part&moisture=average&distance=40.