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Wisdom of the Trees - Part 2

By Jen Beauvais

Deciding on where to plant a tree is an important matter that considers many factors. Depending on your situation, be it planting a tree in a new construction site, or protecting a tree that is already growing, placing a tree in a completed yard, or surrounding your tree with new turf, there are many variables to consider. This article will help you recognize what kinds of measures can be taken to ensure that your tree is placed well and healthfully maintained in various situations.

Trees on the Line

Utility lines can present a challenge to a growing tree that has been incorrectly placed. Besides the lines that we can see on phone poles, utility lines conducting electricity, water, sewage, and natural gas are laid underground where tree roots can either interrupt them or be interrupted. As the root area of a tree is much larger than its crown, it is important that you learn where these utility lines lie before planting a tree.

When planting a tree, it may be a good idea to call your utility company to have service paused while planting. Never, ever assume that utility lines are buried deeper than you plan to dig.

Trees that grow into above-ground utility lines can be dangerous to climbers, animals, and the utility line itself. Consistent maintenance will be necessary to keep the trees branches and foliage from hitting the lines.

Three zones that help to determine the size of trees that are safe to plant commonly exist around a home. There are identified by the International Society of Arboriculture as the "low zone," the "medium zone," and, yes, the "tall zone."

The Tall Zone is the area around a house, most likely in the back yard, that has no phone lines and no underground utility lines. This area could also include streets with no overhead lines with planting areas wider than 8 feet that allow for spreading roots. Meadows, parks and other large areas are also adequate tall zones.

Trees planted here can grow to heights of 60 feet or more. Considerations in planting include how the tree will affect your neighbors view or plans for their own flower beds or trees. Trees should be planted at least 35 feet from a structure to allow for a large root spread.

The Medium Zone is where trees that grow no taller than 40 feet may be planted. This area is where decorative trees that frame a house are planted, possibly in harmony with underground phone lines. Shrubbery may be planted to complement the trees. Adequate soil spaces for planting include areas that are 4-8 feet wide, large planting squares that are 8x8 feet or greater, or other similar open areas.

The Low Zone is appropriate for trees that grow no taller than 20 feet high. This zone extends 15 feet to either side of above-ground utility lines. A low zone is also recommended when growing space is limited, planting areas are less than four-feet wide, planting squares are surrounded by concrete, or raised containers that limit root growth.

Planting trees as windbreaks or to shade your house in warmer weather can help cut down on energy costs.

Keep On the Grass

Growing trees and turf together can present certain challenges. Often, competition between the tree and grass can lead to thinning turf, or to lack of growth in young trees. Tree trunks suffer the wrath of mower and trimmer damage. However, the two can be successfully combined with a few considerations.


What kinds of plant will you be planting in your yard? Lawns and trees are like people: only some will get along. As grass is a sun-loving plant, it tends to not grow well in areas that get less than 50% sunlight, although shade-resistant varieties are being developed.

When the lawn is an important feature of the yard, choose a tree variety that is small with an open canopy that allows sunlight to reach the ground. A tree with a high canopy is also adequate. Choose a tree with roots that grow deeper in the soil so that the surface is available for grass. A point to remember is that surface rooting occurs when topsoil is shallow.

The Race for Nutrients

All plants require sunlight, water, rooting space, and nutrients, resulting in competition between neighboring organisms. Some plants, such as the Eucalyptus tree, will even release toxic chemicals to keep other plants away. Therefore, it's important to give plants space to grow.

Turf and grass both like the same growth area. Tree roots grow in the top two feet of soil with fine, water absorbing roots in the top 6 inches, and turf, well, how surfacey can you get? Grass roots will take up a greater percentage of soil volume than surrounding tree roots will out-compete new trees for water and nutrients. But where trees were first established, their roots tend to compete much better and even prevent the success of establishing new turf.

If you are transplanting a tree, you should remove the sod from around it and give the new transplant extra special attention. Plenty of water, plenty of nutrients, plenty of sunlight. Never do any tilling around trees.

Another alternative to having turf around trees is mulching, which totally eliminates the potential competition. Placing a 2 to 4 inch layer of bark, wood chips, or other organic material on the soil under the drip line of the canopy can help to retain soil moisture, increase soil fertility through decomposition, helps to reduce weeds to control grass, and protects the trunk from mowing and equipment injuries. Mulching also helps to improve soil structure with better aeration, temperature, and moisture conditions.

Keeping it Green

Maintenance methods for your turf can unintentionally affect your trees (and shrubs and flowers for that matter). And since your sod and trees are sharing the same top six inches of soil, treatment of one could damage the other. For example, fertilizer you apply to the sod could be absorbed by the tree and result in more growth than you want.

Herbicides that cause tree damage have warning labors stating this on their packaging. Most herbicides do not kill trees, but soil sterilants and other products do. When herbicides or weed killers are applied to turf, they can spread to trees on windy days, or evaporate and diffuse into the air on hot days. This can affect all the plants in the surrounding areas. Therefore, it is important to check the label before applying chemicals to your plants.

Turf near and under trees should be mowed at its top recommended height. Don't take off more than 1/3 of the grass blade height, and leave the clippings on the grass to supply nutrients.

Trees need one inch of rain or watering every seven to ten days. Shallow, frequent watering does not fulfill the needs of either the turf nor the trees. It can even harm both. In dryer climates where more watering is required to keep grass alive, the extra water can damage the dryland trees and encourage fatal fungi.

Lawn Loopholes

Aesthetics are often important to the owner of a home, and sometimes he or she may be wont to have a level lawn right underneath his/her trees. Adding fill dirt to the area surrounding mature trees can change the ratio of carbon dioxide to oxygen and allow the roots to die. Even just a few extra inches of fill dirt can also smother the roots that are in the top of the soil. To get that perfect lawn directly underneath a tree, it would be prudent to consult a tree specialist so. Preparing a seedbed for lawns often requires that the upper 4-6 inches of topsoil is disrupted. Since this is where the feeder roots lie, disturbing this soil can damage tree tops.

Have Your Tree, and Building, Too!

Construction can be absolutely devastating to trees. Even if the trees don't die right away, they could decline over the years and become apparent long after your construction is completed. If construction is impending, hiring an arborist is important. A professional will help you decide which trees can be saved and will communicated with the contractors in order to protect the trees during construction.

What happens to trees during construction? Equipment could damage a tree, harming branches, bark, and the trunk. An excess of damage could kill the tree.

Digging and trenching necessary for building a structure and installing utilities could result in the severing of tree roots. Remember that tree roots grow 1 to 3 times the height of the tree, and the amount of damage that a tree can suffer from the loss of roots partly depends on how close to the tree cuts are made. Cutting one major root can result in the loss of 5-20% of the root system.

When tree roots are cut, a tree's anchoring system is severed. This increases the chances of the tree falling or blowing over.

The heavy machinery and foot traffic afforded in construction can also lead to soil compaction. Tree roots like soil with 50% pore space, which fills up with water and air. Compacting soil inhibits root growth and penetration and lessens the amount of oxygen that is available to roots.

New construction could mean removing trees. However, the strength of trees in numbers should be considered before suddenly leaving a tree alone. Trees in a forest tend to grow straighter, longer and taller, having each other for protection. Removing neighbor trees leaves a tree open to the elements. Higher heights of trees could experience sun scald on the branches and trunk, and breakage from wind or ice loading in colder weather.

Advice From the Experts

When deciding which trees to remove off a construction site, consulting an arborist could help you to choose the stronger trees that will survive the ordeal. Sometimes, the older trees are worth keeping, and sometimes, the younger more vigorous trees will adapt better to the disruption of their surroundings. Arborists can help you to decide which trees are more sensitive or more immune to construction.

An arborist will also work with a construction crew to help make sure that your trees will survive. The arborist may help make simple changes to plans that would save the life of your trees. For example, tunneling utilities under a tree rather than across the roots causes less damage.

Erecting construction fences as far from the trunks of the trees you want to keep as possible can be the most important action you can take. A general guideline laid out by the International Society of Arborists recommends allowing one foot of space from the trunk for each inch of trunk diameter. This will help to protect the root systems that expand far beyond the drip lines of the trees.

Limiting access to the construction site (the best is one access route) can cut down on the amount of compaction to soil and damage to trees. Instruct contractors where to park, limit areas for burning, cement wash-out pits, and construction work zones. And make these areas away from the tree.

Working with Contractors

Get everything in writing. How you are protecting your trees, what can and cannot be done around the trees, and specified work zone--get it all in writing. And post reminder signs around the site. Write fines and penalties for violations into your specifications. Severity of the fines should be proportional to the potential damage to the trees, increases should be written in for multiple infractions.

Work as a team and communicate with your builders and sub-contractors. Breakdowns in communication, even one person, can lead to irreversible damage. Visiting the site once a day will show the construction team that you are serious about your plans. Taking photos of every stage of construction will help you should anything go wrong and you need to prove liability. And when irrigation installers and other contractors supply the finishing touches to your landscape, be sure to keep communication open with them.

Trees need several years to adjust to injuries and environmental changes from construction. The stressed-out trees will be more open to health issues, like disease and insects. Talk to professionals to get detailed information on how to take care of your trees, and have them evaluated for health and safety dangers.

Treating Construction Industries

Construction injuries often become evident when the tree has already started to decline. Therefore, it's imperative to implement simple treatments right away. Damages caused by construction include injuries to the trunk and crown, soil compaction, root severing, broken and split branches, smothered roots from added soil, and new exposure to the elements.

An arborist will inspect trees visually and using instruments. Pruning to reduce weight, removing unsafe limbs, installing braces or cables, and removing hazards are actions that an arborist will take. If the tree's stability presents hazard to the structure or people, then the best plan may be to remove the tree.

Treating from the Top

The crown of a tree may be injured after construction. Pruning split or torn branches, removal of dead, diseased or rubbing limbs, and possibly even removing lower limbs in order to raise the canopy to provide clearance can help a tree recover. Other maintenance, because of the vulnerability of the tree, should be held off for a few years. Some recommendations say that the canopy should be thinned. However, this can diminish the tree's ability to make food and add more stress. Never top the tree! This will starve the tree and cause weak regrowth.

Should bark be damaged on the trunk or major limbs, carefully remove it. Using a sharp knife, cut away jagged edges without cutting into living tissue.

Wound dressings are not recommended by most experts, for they do not reduce decay nor speed up healing. If dressings are needed for cosmetic reasons, apply only a thin layer of a non-toxic material.

The Long Cool Drink

Not enough water could harm a tree, and yet, so could too much water. If soil drainage is good, keep the trees watered well, especially in dry seasons. Drainage problems could lead to a tree's decline. The top twelve inches of soil around a tree should remain moist. A long, slow soak over the whole root area works well, but do not over water. Don't apply frequent, shallow waterings, either. Surface water should drain away from the tree.

Applying a 2 to 4 inch layer of organic much over the root system helps to maintain soil temperatures and moisture, and cuts down on weed and grass competition. Ideally, the whole root system would be covered with mulch, but apply it as far as your landscape will allow. Never add more than 4 inches of mulch, and do not pile it up against the trunk.

And a Breath of Fresh Air

Soil compaction can be combated by drilling holes and vertical mulching. Drilled holes are usually 2 to 4 inches around, and are bored three feet on center throughout the root area of the tree. Holes should be at least twelve inches deep, but they might have to be deeper if the grade of the soil was raised. Vertical mulching entails that the holes may be filled with peat most, wood chips, pea gravel, or other materials.

Radial aeration consists of narrow trenches cut with compressed air guns like the spokes of a wagon wheel out from the trunk. The trenches are dug 4 to 8 feet from the trunk so as not to cut any important roots, and should extend at least to the dripline. The trenches should be 8 to 12 inches deep, and deeper a new soil grade has been added.

Trenches can be backfilled with topsoil or compost. The roots will grow more robustly in the trenched area than in the soil in the area, helping the tree to adapt to new soil or compaction.

Oh, Poop.

Many professionals do not recommend fertilizing your trees within the first year of construction damage. Because of root damage, water and mineral uptake may be inhibited, and excessive soil salts and pull water from the roots and into the soil. Testing the soil to see if adequate nutrients are available will enable you to add the correct fertilization around your trees. However, extra nitrogen my encourage crown growth while stunting root growth. Until the root system has been able to adjust, leave the fertilizer in the shed.

Monitor your trees for signs of decline. These signs may include fewer, smaller leaves, premature autumn color, and dieback in the crown. A tree that dies because of root damage has a dead anchor and needs to be removed right away. Signs of internal decay include carpenter ants, soft wood, cavities, and mushroom-like structures that grow on the trunk, root crown, or major roots. Look for signs of diseases, as well. An arborist can supply a professional view if you think you see any major damage.

You can do much to ensure that your trees stay healthy. A watchful eye, good advice, and some careful planning can save a stressed tree. However, if a tree presents any danger to homes or people, it may be necessary to remove the tree, despite your great actions to save it.

More information on tree care is available at


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October 13, 2019, 6:54 pm PDT

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