Tree maintenance is the conscious decision by property owners to schedule for the care of the trees in their yards. Homeowners have been busy getting their yards ready for the summer by planting gardens, getting their lawnmower tuned-up, and completing various yard projects. By June, any tree issues will become apparent. They begin to think, when am I ever going to get out of this yard? Give us a call. Let us worry about your trees so you can get on with your summer.
Popular Plunge Damage
Denver experienced a polar plunge last October. We also had a hard freeze in March, which damaged many trees and shrubs across the city. In the fall, warm weather delays a tree’s hardening process to prepare for winter. In the spring, the trees start to leaf out, then get clobbered by a hard frost. In either case, non-hardened trees get flash-frozen damaging their tissues and buds. Over the last 12 months, Maple, Elm, Ash, and Pine trees got whiplashed by these hard freezes in Denver.
Some trees show freeze damage immediately, while others will not show any injury until the spring. Most trees repair themselves, so homeowners should wait until new growth appears before they make any tree pruning decisions. For salvageable trees, the arborist prunes out the deadwood to its secondary branches and reshapes the tree. It’s sad, but any tree that looks dormant or half-dead in mid-June most likely requires tree removal. Sometimes it takes an arborist to check if a tree is viable.
Freeze damage has the following characteristics:
- Evergreens – Early freezes kill the new needle growth on Pine and Spruce trees. These needles turn brown. Most trees recover as new needles emerge in the spring. By June, if the majority of the tree remains brown, it is lost and needs tree removal.
- Deciduous – Frozen trees sometimes keep their leaves over the winter. They drop off during the next growing season. Elms and Maples got walloped by Denver’s polar plunges in October, while Ash trees got stunned by the hard frost in March.
- Newly Planted Trees – Unfortunately, many newly planted trees die after a polar freeze. So this summer, dig up the dead sapling and plant some flowers in its place. Click here to sign up for Denver Digs Trees’ free tree give away next spring.
Pruning Techniques for Frost Damaged Trees
This mature Ash tree above has significant frost damage. About half the tree is dead, but most laymen would say the tree is salvageable. Still, David Boswell, General Manager, and Certified ISA Arborist, said, “This tree probably needs removal because of the amount of canopy loss. The epicormic growth on the tree shows the tree is in decline.”
According to the International Society of Arboriculture (ISA), pruning is the most common tree maintenance procedure. It is best done with an understanding of tree biology because removing a branch is forever. Tree pruning removes dead branches, improves form, and reduces the risk of falling limbs. Tree trimming also encourages healthy growth by opening up the crown to more light and air. Sometimes it takes an arborist with a bucket truck to figure out how to prune a frost-damaged tree to get it back to a healthy, safe, and attractive condition. Below are some tree trimming options:
- Cleaning – is the removal of dead or weakly attached branches from the crown of a tree.
- Thinning – opens the foliage of a tree, reduces weight on heavy limbs, and helps retain the tree’s natural shape.
- Reduction – reduces the size of a tree by pruning back the deadwood to secondary branches that are large enough to assume the terminal roles. Reduction pruning helps maintain the form and structural integrity of the tree.
Pruning Young Trees
Training of young trees is a great way to encourage healthy growth and a desirable structure. Trees with good form require less corrective pruning as they mature. Pruning starts by establishing a single dominant leader growing upward with secondary branches cut so they cannot outgrow the leader.
Summer Feeding and Watering of Trees
A healthy tree usually has a sound root system that anchors the tree to the ground, transports water and minerals from the soil to the rest of the tree, and stores food reserves during the winter. A tree root system consists of large perennial roots and short-lived feeder roots. The perennial roots grow in the top 6 to 24 inches of soil around the tree but sometimes go deeper if conditions permit. Feeder roots average about 1/16 inch in diameter and account for most of the surface area of the root system. These roots grow near the soil surface, where they absorb water, minerals, and oxygen. Tree root systems extend outward past the diameter of the tree’s crown.
It is important to remember that the soils and climate around Denver do not naturally support tree growth. Since trees are not native to Denver, it makes sense that they need supplemental fertilizer and water to grow here. Many newcomers complain about how hard it is to grow grass in Denver. With the right amount of fertilizer and water, grass grows excellent here. The same holds for trees. A well thought out tree fertilization and watering tree maintenance program keeps tree healthy, which makes them less susceptible to disease and insect infestations. They are also able to withstand Denver’s unpredictable weather.
Denver Clay Soils
Most gardeners in Denver would use the phrase “notorious clay soils” because it takes more work to get trees and plants to grow here. Some trees grow poorly in clays soils because of lack of aeration, which decreases the ability of the root systems to replenish water loss brought about by our dry climate. Overwatering heavy soils compound the problem by reducing the amount of air and oxygen available to roots. So it is safe to say that most trees in Denver because of our dry climate and clay soils benefit from some form of fertilization. Homeowners should look for the following:
- Stunted Growth – Your tree is not growing as fast, or the leaves seem smaller than expected. Clay soils do stunt growth, and fertilization reverses this condition.
- Leave Discoloration – Leaf discoloration is a sign of infestation or disease, but it could be that your trees are not getting enough nutrition. Red and Freeman Maples and some Oaks are prone to Chlorosis or yellowing of leaves. Affected trees cannot take up iron from the soil, so their leaves turn yellow.
- Newly Planted – Freshly planted trees are low on nutrients and need fertilization to keep them growing.
Ross Tree’s three ISA Arborist and three Quality Supervisors licensed by the Colorado Department of Agriculture will apply fertilizers in the manner prescribed by the manufacturer and regulatory agencies. Below are products used as tree fertilizers.
- Cambistat – regulates tree growth and strengthens root systems.
- Biochar – breaks down hardened soil allowing root systems to expand and grow. Biochar allows essential microbes to thrive in the ground improving soil structure.
Chlorosis or Yellowing of Leaves
Maples and some Oaks with yellow leaves during the summer most likely suffer from an iron deficiency. Denver’s high alkaline soils make iron unavailable to the root systems of some trees. Trees roots struggle to take up the element, and the Chlorosis worsens as the summer progresses. Affected trees decline and eventually die if the iron deficiency is prolonged and not corrected.
One way to avoid Chlorosis is not planting tree species intolerant to Denver’s clay soils. Homeowners experiencing Chlorosis should call a certified arborist. Once on-site, the arborist will inspect the trees, identify species, and select the best fertilizer to remedy the situation. One of the most common therapies injects an iron solution into the trunk of the tree every few years. Applying chelated iron fertilizer is another option. These fertilizers amend the soil and make iron available to a tree’s root system. We do not recommend liquid iron foliar applications since these products stain concrete and can disfigure the leaves of trees.
The amount of water a tree needs depends on its size, amount of stress, sun exposure, and soil type. Watering too much is just as damaging as too little water, so sometimes it is best to contact an expert to get the watering volume and frequency right. Below are several watering tips.
- Water Injection – Tree service companies use deep root forks or needles to inject water into the ground from the trunk to the dripline at a depth of 8 to 12 inches.
- Consistent moisture – Maintaining soil moisture allows for better root absorption of water. Dried-out or waterlogged soils make trees vulnerable to disease and insect infestations, as well as branch dieback.
- Newly planted trees – Young trees need water every three or five days after planting. Also, be sure to water them during drought conditions in the summer and winter.
- Rule of Thumb – Apply 10 gallons of water per inch of tree diameter. For small trees, this is not a big task. Still, for larger ones, we recommend calling a professional tree service company that possesses the water tanks, injectors, and other equipment needed for larger jobs.
- Mulch Trees – Wood chip, bark, leave, and evergreen needle mulch conserves soil moister but leave a six-inch space between the mulch and trunk of trees.
Most homeowners know to water their trees in the summer; however, trees need watering during the fall and winter, too. During dormancy, most root systems still grow, so they need moisture to survive the winter. All yard trees and shrubs need supplemental watering during dry winters with little snow cover and drought conditions.
Since Evergreen trees keep their needles, they need more water to survive because their needles expire water all winter long. Winter winds compound the problem by pulling more water out of the plant. Evergreens planted on the south or west sides of homes need more water because of their exposure to Colorado’s hot sun. Homeowners need to check the soil for dryness and watch for any browning of needles. Deciduous trees drop their leaves in the fall to conserve water. However, even during the winter, hardwood tree root systems continue to grow, and their twigs lose water, so they need watering to survive. Homeowners with shallow-rooted species such as Maples, Lindens, Birches, and any recently planted trees need to take particular care of these trees during winter dry periods.
Below are some winter watering tips:
- Water trees during a warm day before it freezes, so their roots can absorb the water. Watering frozen ground wastes water and time.
- Water your deciduous and evergreen trees up to two times a month between October and March.
- Dig down at least 4-6 inches around the dripline to check soil moisture levels. If dry, the tree needs watering.
- Water deciduous trees within their dripline. For evergreens, water on all sides of the tree several feet beyond their dripline.
Tree damaged from lack of water during winter shows up the following spring as branch dieback, reduced leaf size, Chlorosis, or a dead tree. However, watering during the fall and winter months avoids these problems and prepares the trees for robust growth during the next growing season.
Why not depend on a professional service company to show up in June and take care of any issue your trees are dealing with at the beginning of the summer? Hiring a tree maintenance company allows homeowners to start enjoying their summer rather than worrying about their trees. Need tree maintenance, click here to fill out a request service form or call 303-871-9121.