ISA Rocky Mountain Chapter

Selection

If carefully selected and placed, trees can provide unmatched benefits to your property. Different tree species have different requirements for their planting location. A tree that is poorly matched with its planting location may become unattractive, obstructive, or even hazardous. To avoid this, evaluate your location first, and then find a tree that will flourish there. ISA Certified Arborists are well equipped to evaluate possible planting locations and recommend tree species.

Choosing a Planting Site

Future Growth

Start by thinking about what you want your yard to look like in 10 or 20 years. The key to analyzing a planting site is to envision it with a full-grown tree. Although the new tree you are considering planting probably will be only 5 or 10 feet tall, it may grow to 50 or 100 feet, depending on the species.

Consider other trees, buildings, or landscape features near the site.  Tree roots need space, too, and don't like to be confined by sidewalks, driveways, or house foundations. Watch out for overhead utility lines, pedestrian and vehicular traffic routes, buildings, signs, and street lights that the tree's canopy and roots may run into. It's best to choose a tree that will naturally have clearance instead of planting a large tree that will require constant pruning to maintain safety under overhead power lines and other obstructions. A good rule of thumb is to only plant trees that will be less than 30 feet tall at maturity and within 30 feet of overhead obstructions.

Soil

The health and vigor of your tree will greatly depend on the quantity and quality of the soil in the planting site. Trees need plenty of soil to grow strong and stable. Adequate volumes range from 400 to 1,000 cubic feet depending on the mature canopy spread. A good rule of thumb is to assume your tree will need 1.5 cubic feet of soil volume for each square foot of mature canopy, using a depth of 3 feet. Inadequate soil volume can restrict root growth and decrease tree stability.

Soil near houses tends to be highly compacted, which is less than ideal. For growth, tree roots must have loose or uncompacted soil with oxygen.

Most soils don't require amendments. However, if your soil is sandy, has a high clay content, or has been heavily disturbed by construction, soil amendments can create a better planting site for trees. Soil amendments like loamy topsoil, peat moss, and mulches can enhance the soil's moisture-holding capacity, nutrient availability, or structure. In particular, additions of organic matter will help clay soil. This soil is easily compacted, which obstructs the movement of water and air. Mixing in organic matter helps break up clay particles and improves water and air flow around the roots. An ISA Certified Arborist can help you identify your soil composition and recommend amendments.

Alternatively, you can choose a tree that will work with your soil. Some species thrive in extremely wet or dry soils. To ensure a healthy tree, you should find a species that is suited to your soil's pH.

Wind, Sun, Climate

If your property is subject to strong winds, you will need to select a species that is more resistant. Young trees may also need to be staked for the first year after planting.

Some trees tolerate shade while others prefer full sun. Consider how much sunlight your location receives throughout the year.

The climate of your property will dictate which trees will thrive, with rainfall being the foremost consideration. Ornamental and shade trees in dry areas will need to be  planted in an irrigated landscape or regularly hand-watered in order to survive.

Selecting a Tree

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Once you have analyzed your tree planting site, you can match it with an appropriate tree species.

When selecting a species, keep the purpose of your tree in mind. For example, if you're looking for a privacy screen, a maple is a poor choice because it doesn't hold its leaves year round. However, a cedar is ideal for this purpose. If the tree's primary purpose is shade, an oak, maple, or ash may be at the top of your list.

Although it may be tempting to choose a fast-growing tree in order to quickly reap the benefits of your tree, remember that fast-growing trees sacrifice structural capabilities in their quick ascent to form a canopy, which can lead to weak branches that can easily break and fall. Slower growing trees are generally stronger structurally.

If you are selecting multiple trees for your property, plan for diversity of tree species and varieties. This will prevent pests or diseases from spreading and add visual interest to your landscape.

Researching Trees

Depending on where you live, an arboretum or botanical garden may be nearby.  This is an excellent place to discover tree species, because everything is labelled and most trees will be in their mature form. Take a notebook with you and write down the names of species that appeal to you.

You can also connect with local experts. In addition to local ISA Certified Arborists, your city forester or county extension agent may recommend trees for your area.

Many books and websites can help you choose a species to match your planting site. We have listed several that we recommend on our Resources page.

Tree Types

Here are some types of trees you can consider when making your selection.

Shade

Shade trees are deciduous, meaning their leaves turn color and drop off in the fall. This makes them ideal energy savers, because they create shade in the summer and let in light during the winter. Shade trees are best planted at least 25 feet away from houses, buildings, or other obstacles.

Conifer

Conifer trees, also known as evergreens, have needles or needle-like leaves that usually stay green all year. Conifers are the best choice for windbreaks and privacy screens.

Ornamental

Ornamental trees are usually chosen for a particular characteristic, such as spring flowers, fall color, an attractive bark, or crown form. Small ornamental trees with a mature height of less than 25 feet work well under utility lines or in confined spaces.

Native

Native trees are those that grow naturally in your area. Depending on where you live, native trees should fit well in the home landscape, especially along streams or open areas. However, they might not be suitable for urban areas. If you live in a city with harsh growing conditions and poor soils, instead consider an ornamental or shade tree that tolerates urban environments. Avoid exotic species that may prove to be invasive later.

Selecting a Tree

After evaluating your planting site and deciding what tree species and types to look for, visit a nursery or garden center. There you will find trees with roots in three states: containerized, bare roots, or balled and burlapped (known as B&B). Each method of moving trees from the nursery field to your yard has its advantages and disadvantages.

  • Containerized trees are more easily protected and transported. For that reason they are favored by many nurseries. However, if the plant is left in the container too long, the growth pattern of roots will be warped by the confined space, damaging the tree's chance of survival. Generally, containerized roots work better for smaller tree species.
  • Bare root trees tend to be less expensive and are easier to handle (they're lighter without the soil), but you have to use extra care to keep the roots moist during transport.
  • B&B trees are planted out in the field, dug from the ground, and bound in burlap. This means that some of their roots are broken and left behind. However, the roots are allowed to grow more naturally. This is often the best choice for large species.

Don't just purchase the cheapest tree you can find - you may pay for it later. It may be an undesirable species, have poor form, or have some other problems. Any of these problems will greatly reduce the tree's chances for a long, attractive, healthy, and productive life in your home landscape. Inspect any tree you are considering purchasing for the following aspects:

  • Roots. Make sure your tree has an adequately sized root ball. A general rule of thumb is 10 inches of root for every inch of caliper - the diameter of the stem 6 to 12 inches above the base. If possible, check to ensure there are enough sound roots to support healthy growth. Broken or circling roots in a small root ball or small container is a bad sign.
  • Branches. Look for a sapling with well-spaced, firmly attached branches. Branches should be thinner than the caliper and spaced at least 8 to 12 inches apart for most species.
  • Wounds. Check the trunk for mechanical wounds or wounds from incorrect pruning. Any wounds this early in a tree's life will lead to issues down the road.

Transport

Once you've selected your tree, you'll need to transport it carefully to the planting location. Trees are often damaged or stressed during the trip home from the nursery.

Take special care to reduce injuries when loading and unloading your tree. Move the tree using only the root ball or container; using the tree trunk as a handle can break tree roots or even the trunk.

Protect trees from wind and heat damage during transport by wrapping the whole tree, including roots, with a tarp or landscape fabric. Cushion stems and branches, particularly if they rub against the vehicle. Tie the tree securely and avoid high-speed travel.

Plant your tree as soon as possible. If you must store it before planting, put it on the north side of a building away from direct sunlight and heat. Protect the roots or root ball with mulch or other protective measures, and keep the roots or root ball moist to prevent them from drying out. If you can't plant the tree within one to three days, make arrangements to leave it at the nursery until you have time to plant it.

When you buy a high-quality tree, plant it correctly, and treat it properly, you and your tree will benefit greatly in many ways for many years to come.

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