UNITED STATES—Trees are generally the most significant living components within a home garden. Even treeless gardens benefit from nearby trees. Some old redwoods contain more wood than the homes that they shade. Some old oaks inhabited their gardens centuries before their gardens did. With few exceptions, nothing in a garden is as big or permanent as a tree.

Japanese maples, citrus trees and other small trees can be among the exceptions. They might be smaller than some of the shrubbery they share their gardens with. Papayas and other herbaceous trees can also be exceptions. Some live for only a few brief years. The definition of what a tree is can be vague. Variable interpretations complicate this matter.

A tree is a woody perennial plant with a single tall trunk and branches. However, banana  trees develop several unbranched herbaceous trunks. Palms and tree ferns are neither woody nor branched. Arboriform yuccas are no woodier than palms. Many trees develop many trunks. Banyans use roots as trunks. This definition does not even describe ‘tall.’

Selection of an appropriate tree involves many variables.

Ultimately, the characteristics of a tree are more important than its definition. Shade trees near homes should be deciduous to let warm sunshine through in winter. Evergreens are better for obscuring unwanted scenery throughout the year. Evergreens are messier than most deciduous vegetation though. Their shedding is not so limited to distinct seasons.

Fruit trees are some of the most misunderstood inhabitants of home gardens. Not many grow big enough to function as shade trees. Fruit is difficult to harvest from those that do. Almost all require intensive and specialized pruning and maintenance. Few get it. Most eventually succumb to neglect. Citrus and avocados are some of the least demanding.

Palms, whether or not they qualify as a type of tree, are also misunderstood. They lack branches, so they are not conducive to pruning away from utility cables. Their single terminal buds grow only upward. Removal is the only option for palms that encroach too closely to high voltage cables. Even the best palms need grooming from professional arborists. Most quickly grow beyond reach from the ground or even a ladder and are dangerous to climb.

Highlight: Colorado Blue Spruce

Most trees behave very differently in cultivation than in the wild. Colorado blue spruce, Picea pungens, is naturally a grand tree. It slowly but surely grows almost a hundred feet tall in the Rocky Mountains. Locally, if not competing with taller trees, it rarely gets as tall as 30 feet. Mild winter weather does not stimulate much more than necessary growth.

Furthermore, most home garden Colorado blue spruce are densely compact cultivars. Most are plumply conical. A few are quite rounded or globular. They function more as big shrubbery than trees. They are less conducive to major pruning than shrubbery though. Removal of low limbs for clearance compromises their strict but naturally elegant form.

Foliar color is as appealing as form and foliar texture. Obviously, Colorado blue spruce should be blue. Some are a bit more silvery or grayish. Trees that grow from seed tend to be greener and a bit less dense than cultivars. Such seedlings are sometimes available online. The stiff and prickly needles of Colorado blue spruce are only about an inch long.

Tony Tomeo can be contacted at tonytomeo.com.