Pruning Trees and Shrubs in Tucson
Pruning is the removal of plant parts, including shoots, branches, fronds, and flowers to improve a plant’s health, control its growth, or influence its blooming cycle. Pruning should be a routine part of landscape maintenance practices. Proper plant selection and knowledge of plant varieties and their size at maturity will help eliminate the need for major pruning. If a tree needs to be pruned several times each year to control its size, it may be the wrong species for a particular location.
Plants are pruned for a number of reasons, so determine why you are pruning a plant before making that first cut. The main reasons for pruning include safety and the tree’s health and aesthetics. Pruning is also used to stimulate fruit production. When pruning for safety reasons, remove branches that could fall and cause property damage or interfere with lines of sight on streets or driveways. Remove branches growing near utility lines. However, always consult your local utility company or call a certified arborist for help. Never prune trees that are touching utility lines. For safety purposes, prune trees that obscure the entry to your home.
When plants are pruned for health, it might involve removal of diseased or insect infested parts. This is an effective way to limit the spread of decay, disease, and insects to portions of the plant or to neighboring plants. Branches may need to be removed that are crossing over other branches or crowding out the crown of the tree. If branches are broken due to storm damage, it is a good idea to prune them.
When pruning trees for aesthetics, the goal is to enhance character and shape or to stimulate flower production. Pruning should only be done when there is a good reason to prune. For example, the limbs of a tree might interfere with the roof or side of a house, or it might need to be shaped because the top or sides are growing too big for a planting space. Selective pruning thins a thick canopy and allows light to penetrate through the tree, and can give the tree a more balanced appearance.
Pruning and maintaining a solid plant structure should begin when trees are young. This helps produce strong branches and influences long-term health. A tree’s branch spacing and structural safety are controlled by selectively removing or shortening branches. Always encourage one central trunk to develop by removing or reducing the length of competing upright trunks or branches. When determining what branches should be removed, follow this guideline: If the cut is less than two inches in diameter, go ahead and prune. If the cut is between two and four inches, think twice before pruning. It the cut is greater than four inches, have a good reason to prune the tree. If in question, do not prune. Careful, selective pruning results in a beautiful, healthy tree that enhances your landscape for many years.
Pruning Large Established Trees
Contact a qualified tree care professional who has the right training, equipment, and knowledge to prune large, established trees in your landscape. Large-tree pruning requires climbing, heavy chainsaws, and even bucket lift trucks. Never compromise personal safety when pruning a tree.
The three most common types of tree pruning on established landscape trees are crown thinning, crown raising, and crown reduction. Below is a description of each.
Crown thinning: Crown thinning is the process of selectively removing branches on young trees throughout the crown or in the top of the tree to help develop a tree’s structure and shape. This procedure increases light penetration and air movement into the tree. No more than one-quarter of the living crown should be removed at any time. This technique involves removal of any branches that rub or cross another branch.
Crown raising: Crown raising is a pruning method that removes lower branches from the bottom of developing or mature trees. This may be done to provide clearance for pedestrians, vehicles, and buildings, or a line of sight. Always maintain live branches on at least two-thirds of the tree’s total height. Removal of too many lower branches hinders development of a strong stem.
Crown reduction: Crown reduction is a method used when a tree has grown too large for its permitted space. Removal of larger branches at the top of the tree is done to reduce its height. When pruned properly, this method is different from topping because it results in a more natural appearance and minimizes stress to the tree. Crown reduction is a method of last resort and the least desirable pruning practice. A better long-term solution would be to remove the tree and replace it with a smaller plant specimen.
Proper Pruning Methods
When pruning larger branches, three separate cuts may be necessary to avoid tearing the bark. Make the first cut on the underside of the branch, at the branch collar, which is a shoulder or bulge formed at the base of a branch by the annual production of overlapping layers of branch and stem tissue. On the upper surface, there is a branch bark ridge that runs along the stem of the tree. The ridge is formed by the stem and branch tissue as they grow against one another. A proper pruning cut does not damage either the branch bark ridge or the branch collar. Make pruning cuts just outside the branch collar. The branch collar contains trunk or parent branch tissues. The tree may be damaged if you cut into the collar. If the cut is too large, the tree may suffer permanent internal decay from an improper pruning cut. Make the second pruning cut just higher on the branch than the first cut. The third cut may be made by cutting down through the branch, severing it. Do not ever leave a stub.
You would be wise to begin pruning trees when they are young to correct structural problems, because waiting to prune a tree until it is mature will create the need for large cuts that can cause problems for the tree. Poor pruning practices can damage a tree, so learn where and how to make the cuts before pruning. Trees do not heal when cut improperly. Small cuts do less damage than large cuts. If you cannot avoid large cuts, follow the instructions in this chapter, and generally avoid wound dressings and pruning paint. They are not necessary, and research has proven wrong the old belief that they speed wound closures and protect against insects, diseases, and decay. If a dressing must be used for cosmetic purposes, use a thin coat of material that is not toxic to the plant.
Pruning of deciduous trees should be done during their period of dormancy when all of their foliage has dropped, usually between mid December and the middle of January, well before their spring buds begin to swell. Also, pruning in winter makes it easier to see crossing limbs, excessive crowding, and branches that might be in need of pruning.
Pruning Dead Branches
Pruning dead branches is similar to pruning live ones. The cut is usually easy because the branch collar and branch bark ridge are more easily observed in dead wood. Still, be careful to make the pruning cut just outside the branch collar. Large, dead branches should be supported with one hand or cut in the three-step method, just as live branches are pruned. If a limb is large and heavy, its weight should be reduced before attempting to prune. Use the three-cut method by making the first cut under the branch about twelve to eighteen inches from the limb’s point of attachment. Make the second cut from the top, a few inches farther out on the limb. This removes the heavy limb without tearing or ripping the bark from the tree. You will be left with a stub that can be pruned back to the branch collar.
Topping of Trees
Topping of trees is not recommended. It is a misguided practice that shortens a tree’s lifespan. After a deciduous tree is topped, its growth rate increases dramatically in an attempt to replace its missing leaves and foliage, which are a source of nutrients. Many long, skinny shoots called water sprouts or suckers form. Theses are weak and unsightly and they must be cut and re-cut every year. This creates a major maintenance problem in the yard. The tree needs to be repeatedly pruned and eventually removed when it dies or when the owner gives up this expensive, vicious pruning cycle. A properly pruned tree requires less maintenance than an unsightly topped tree.
The practice of topping is evident on many older mulberry and chinaberry trees growing in the Southwest desert. These trees have responded by growing back to a normal height, but they lack their original, beautiful silhouettes and structural integrity. Instead, they sport unsightly suckers and shoots making then susceptible to wind damage. This improper pruning has also caused injury, and has depleted these trees of stored food reserves. As a result, many end up diseased or dead.
If a large tree outgrows its space, it should be pruned using the crown reduction method, which allows for a natural appearance while correctly reducing the height of the tree, stimulating new growth throughout the tree and minimizing stress.
Pruning is an important practice for maintaining shrubs. Doing it successfully requires an understanding of the individual growth habit of each plant and when they flower. Shrubs come in many shapes and sizes. A properly pruned shrub is a work of art and beauty, because when trained into a particular shape or form, its natural characteristics, colorful flowers, or abundant berries are allowed to emerge in full.
When pruning, cuts should be hidden inside the plant where they are covered over by remaining leaves. The first step in pruning is to remove all dead and diseased or broken branches. Remove branches that might cross over other branches, or which look out of place. If the shrub is too large, remove some of the older branches first. When shrubs are sheared back routinely, lots of dense, new growth may be produced near the outer parts of the canopy. Light cannot reach the interior of the plant and it becomes top-heavy; little or no growth happens near the bottom. If you notice this pattern in your landscape plants, selectively cut the excess vegetation to a side branch or main trunk and let the plant grow back.
Control height by making cuts inside the shrub—always make pruning cuts so they remain hidden. This method reduces the height without sacrificing the shape of the plant. When older shrubs grow out of proportion to the landscape, they may need pruning in order to rejuvenate. Also make sure that you are pruning at the right time. Frost-tender vegetation should be pruned back to live wood in early March after the chance of a last frost has passed.
Select an appropriate pruning method for your plant species. Consider how pruning a particular plant might affect the landscape. How quickly can the plant recover from drastic pruning? Give extra care to heavily pruned shrubs. Fertilization, water, and possible pest control are critical factors when considering rejuvenation pruning techniques.
Common landscape plants such as crape myrtle, nandina, gardenia, salvia, camellia, floribunda roses, and other flowering shrubs should be pruned in late winter or early spring before growth begins. They produce flowers on the current season’s growth. Old, dead flowers should be taken off at this time, too. Tender plants like bougainvillea, lantana, bird of paradise, plumbago, yellow bells, dwarf oleander, ruella, and shrubs that freeze back every year need to be pruned back to live wood in late winter or early spring. Don’t prune back frozen vegetation too early after a freeze. The frozen vegetation acts as a coat to protect the live wood from further damage. It is wise waiting to cut back this growth, even if plants look unsightly. The last frost in the Southwest desert generally occurs in mid March, depending on where you live.
A word of caution: When pruning the desert spoon, do not take too much of the lower growth off. If these species are over-pruned they tend to look like a pineapple. The same techniques apply to the Sago palm and Mediterranean fan palm. Removing minor growth touching the ground, or just enough to cosmetically shape the plant, is adequate. It is better to prune a little than to over-prune. When pruning agave species it is a good practice to remove the bottom dead or dried-out leaves. Aloe ferrox and other tree aloes can show signs of frost damage in extremely cold winters. When frozen, the tips of the plants dry out and turn a crusty brown. Take hand clippers and prune off the dry, crusty ends of the plant. The cuts eventually callus over. Since aloes grow back from their core, the plant will eventually recover. Carefully prune back dead, diseased or frozen pieces of succulents and cactus when needed. It helps to wear protective gloves when pruning these plants to protect your arms and hands from serrated thorns. Also, use a small saw to remove dead growth. Plants like rosemary, pyracantha, and acacia develop dead wood in mature plants. Sometimes, the dead sections of these plants need to be drastically pruned in order to remove unsightly stumps and stimulate new growth.
Hedges are shrubs planted close together in a row to form a windbreak or high screen. They should be allowed to maintain their natural form and characteristics. Pruning of hedges is needed to keep them looking dense or to remove dead, diseased, or broken branches. Keep hedges pruned so that they are wider at the base than at the top. Hedges that grow all season long need to be periodically trimmed throughout the spring and summer. A hedge will be thicker and better looking when cutting small amounts more frequently.
Prune when newly planted hedges begin to show signs of new growth. Don’t wait until a hedge gets too high to start training. Light, frequent trimmings help the plant to grow gradually and eventually become an attractive, thick hedge that is evenly horizontal at the top. The best guideline for pruning hedges is to simply prune them whenever they look like they need it. To rejuvenate an old neglected hedge, cut back in the spring to a few feet above the ground. Then prune lightly as needed.
A tree stump is what remains of a living plant that has been cut down. It is often unsightly and hazardous, and encroaches on garden space. The stump should be removed. Of the few ways to do this, the easiest is to hire a certified arborist to remove the stump with a stump grinder.
A stump grinder is a power tool that removes the stump with a rotating, cutting disk that chips away at the wood. It comes in a variety of sizes with a high-speed disk with specially designed teeth that grind down the stump to about 12 inches below the ground level, as well as underground roots. What remains are small wood chips. Once the tree stump is removed you can install turf, landscape plants, or another tree.
It takes a stump many years to decay if left untouched. However, some products are available on the market that can be applied to a stump to speed decay. You will need to drill many holes into the stump and pour the liquid into the holes. After three to four months, the chemical begins to break down the wood fibers of the stump, leaving them porous and able to absorb kerosene. At this point, ignite the stump, keeping a watchful eye on containment. Allow the stump to burn to the ground.
Small stump grinding machines may be rented if the operator is properly trained. Eye protection is required along with other safety gear. If unsure, it is always best to hire a professional.
Pruning tools are available in a wide range of styles, prices, and brands. When purchasing tools, shop for the best quality and durability that you can afford. Always keep pruning tools sharp to produce a cleaner cut that helps the plant heal faster and places less stress on your hand and wrist. Also, clean tools after you use them. A pruning cut on a diseased branch can spread infection throughout your landscape.
Most pruning tasks are accomplished by using hand clippers, loppers, pole pruners, hedge shears pruning saws, and for larger cuts, chainsaws are needed. Hand pruners are the most important of all the pruning tools. They are versatile for small pruning jobs and for cutting twigs and branches up to three-quarters of an inch in diameter. They come in handy when pruning frozen growth on most groundcovers and smaller plants, or to remove dead palm fronds or leaves.
When pruning larger branches more than one to two inches, loppers are the best choice. They are like scissor-action hand pruners; except they have longer blades and a long handle that increase leverage. When using loppers, it is best to cut in one smooth stroke to avoid injuring the plant. Loppers need to be used with both hands. Good quality loppers can slice though branches of two inches or more, depending on the plant species and condition of the wood. Loppers are excellent when pruning smaller branches on trees, because their long handles not only increase your leverage but also help to get inside the tree. When pruning back dead sections of plants a lopper will cut deeply into the branch to quickly prune dead or frozen wood.
Pruning saws work best on pruning cuts larger than two inches in diameter. They have narrow blades for easier maneuvering and coarser teeth than common carpenter saws. There are many types of pruning saws available. Special tri-cut or razor-tooth pruning saws cut through larger branches with ease. Avoid folding saws—they have a special wing nut that can scar the trunk when a limb is cut, and if the saw suddenly folds while in use, it could injure you. A fixed blade saw is much safer. Blades can be straight or curved. A double-edged saw has fine teeth on one side and is coarse on the other side, but can be hard to use in densely branched plants. Bow saws are useful only when there is no obstruction above the area where you are cutting.
Pole pruners remove branches from trees that cannot be reached from the ground. Most pole pruners have a cutting blade and a saw. The cutting blade can be operated from the ground by using a long rope that is pulled downward. Sometimes, pole pruners have poles that fit together in sections to extend them for special jobs. When selecting one to buy, consider that the wooden pole pruners are heavy, while white aluminum poles are lighter and easier to use. And in general, avoid using pole pruners near power lines. Material cut overhead can fall on you, so always use caution and wear head and eye protection.
Use hedge shears to shear or clip hedges or other plants for a neat, trimmed appearance. Never try to cut large branches with hedge shears. Hedge shears can be manual, handheld, gaspowered, or electric. Manual shears have long, flat blades and short handles, one for each hand. Heavy duty gas-powered or electric shears are best for difficult jobs.
Chainsaws should be used when pruning large branches over two inches in diameter. They come in a variety of sizes, in both gas and electric models. Before beginning your job, make sure the chainsaw is sharp, and also check the chain tension and lubrication for proper function; this ensures long chain life and safer cutting. You should always wear leather work gloves, eyewear, steel-toed work boots, and close fitting clothing. Proper clothing and equipment can reduce injury, but always use chainsaws with extreme caution.
Before cutting, always look up into the tree. Overhead hazards can include dangerous wires, other trees, or dead and loose branches. When making pruning cuts, always stand to one side of a limb—never straddle it. Consider where the chain might go if it snaps. Never position yourself or other people in line with the chain. Keep the chain out of dirt, as debris will fly, the teeth of the chain may become dulled, and the chain life will be shortened considerably. When pruning, always keep the tree limb or a similar barrier between yourself and the saw blade. Larger limbs may require more than one cut to be removed safely. Before cutting any tree, check the diameter of the branch. If it is more than four inches or may require special cutting techniques, then it is a good idea to call a professional.
Keep all pruning tools in good shape. Sharpen and oil blades at the end of each use, or at least at the end of the pruning season. Sharpen only the outside surfaces of the blades so the insides surfaces remain flat and slide smoothly against one another. It is a good idea to have pruning saws and chainsaws sharpened by a professional. Treat wooden handles with linseed oil. Wipe off blades with a cloth and oil them with common household oil. Store all tools in a dry, safe location.
If any pruning job is too big or unsafe for you to handle, or trees are growing into electrical lines, please call in a landscape professional or certified arborist. These highly trained individuals are equipped and certified to handle all tree issues and problems. The International Society of Arboriculture (ISA) is an organization of people who have achieved a level of knowledge and competence in the art and science of proper tree care. Their acute knowledge and maintenance of trees is an investment that can enhance the longevity of a tree. To become a certified arborist, you need to pass a comprehensive examination developed by some of the nation’s leading experts on tree care. Arborists must continue their education to maintain these certifications. This keeps them well informed on the latest techniques in arboriculture.
Well-cared-for trees that are properly maintained and attractive add considerable value to your property. If trees are poorly maintained, they become a liability. Trees that need major pruning or removal can also be dangerous. An arborist helps determine the type of pruning that is needed to preserve the health, appearance, and safety of trees. In a severe storm that may cause a tree to uproot or limbs to fall, an arborist can assist in the safe removal of the tree without further risk to property. Additionally, an arborist recommends types of trees to install, helps with cabling or bracing of tree branches, and treats diseases and insects. When looking for an arborist, check with the International Society of Arboriculture; search the Internet or the phone directory.
Mistletoe Removal from Trees by Pruning Methods
Mistletoe is a flowering evergreen that grows as a parasite on a number of landscape plants in the Southwest desert. It has thick, green leaves that are oval in shape, and it grows up to two or more feet in diameter, producing small, sticky, whitish berries from October to Fried / Southwest Landscaping / 160 December. Evergreen clumps of this parasite are easily seen on deciduous trees in winter when all of the leaves have fallen.
Mistletoe plants are either female or male, respectively producing either berries or pollen. Both male and female plants must exist in close proximity for pollination and fruit development. Birds feed off of the berries, digest the pulp, and excrete the seeds, which can then stick to the branches of living trees. When the seed germinates, it grows into tree tissues. It may take up to two years for the plant to bloom and produce viable seed. Seeds may also fall from mistletoe in the upper parts of the trees creating new infestations on lower branches. The parasitic plant depends on its host plant for water and nutrients, eventually causing decline over a period of years. Severe infestations cause the host tree to lose limbs and eventually die. At different elevations in Arizona and other states, mistletoe infects many trees and shrub species, including palo verde, mesquite, cottonwood, ash, sycamore, ironwood and acacia.
The most effective way to control this parasite is to prune out infected branches as soon as they appear. Cut the mistletoe from the host tree before its roots become deeply embedded in the tree limbs. Infected branches should be pruned at least one foot below the point of plant attachment. Heavy infestations may require you to remove the entire tree. At a minimum, prune the mistletoe from infected trees every six months to keep this parasite in check.
Mesquites infested with mistletoe parasite