Contrary to popular belief, tree pruning bears little resemblance to a “haircut.” The better metaphor is invasive surgery.
Every pruning cut is a wound the tree must react to, repair, and attempt to close. Inflicting such wounds changes the balance of tree growth hormones by eliminating their production sites in the tips of branches. If we take too much material, the tree will enter a shock response, producing more growth and becoming vulnerable to pests and pathogens. If we take too little, we don’t make enough of a difference in the resilience of the tree’s structure. On top of it all, pruning must take into account the physical response of the tree’s canopy to wind, snow, and ice, and must endeavor to leave the tree stronger than it was before. As you can see, pruning is a balancing act – a carefully considered application of biology and physics and a subjective application of aesthetic principles beyond that. Tree care in general and pruning in particular is truly an art as well as a science!
Mature Tree Structural Pruning
Structural Pruning is a future-focused method aimed at encouraging a strong, resilient structure with a clear central leader and solid, properly-proportioned, scaffold-like lateral branches.
While “Structural Pruning” in the literature is aimed primarily at training young trees, we believe that these ideas can be applied to mature trees as well. When pruning larger trees, we seek to reduce lengthy or vulnerable lateral limbs while allowing the center of the tree to grow essentially unimpeded.
Since mature trees often have a visible life history in the form of accumulated damage, poor form, and defects, we inspect the tree carefully before we ever set a rope in the canopy. We take into account anything that might weaken the tree and attempt to compensate with thoughtfully-placed cuts.
We endeavor to never remove more than 15% of a tree’s live tissue. Some pruning standards (researched in locations like Florida) advocate for pruning up to 30% of a tree’s canopy, but growing trees in Colorado is a challenge! Trees in the Front Range contend with heat, cold, drought, frost, and snow storms, along with more universal urban tree stresses. By avoiding overpruning, we minimize stress and the unhelpful tree responses that result from it!
Young Tree Training
Our Young Tree Training protocol closely follows Dr. Ed Gilman’s Structural Pruning methodology, encouraging trees to grow a strong central leader with scaffold branches less than ⅓ the size of their parent stem. This form has proven in study after study to be resistant to storm and wind loading.
Young Tree Training is applied to trees under about 20’, with stem sizes under 6”. Basically, anything too small to climb.
Early pruning is probably the most effective way to create strong, healthy tree structures for the future. Six or seven small, well-considered snips every two or three years when a tree is young can avoid a life plagued with storm damage and can even prevent catastrophic failure by building a better tree!
Young Tree Training feels like doing “the Good Work” in many ways. We make such a HUGE difference for the future of the tree when we can get in there early. So much of mature tree pruning can be dedicated to mitigating issues that could easily have been avoided by 15 years of affordable young tree training visits!
Restoration Pruning
Sometimes, disaster strikes for your trees in the form of a damaging snow, wind, or ice storm. Even the most meticulously-maintained trees can be damaged in a catastrophic weather event. When the unthinkable happens, a different set of tools and a cautious, thoughtful outlook is required.
Restoration Pruning aims to do several things in order:
First, make the canopy safe.
Damage to trees often results in hanging branches, split trunks, torn stems, and other sources of weakness. The very first step in restoration pruning is to make sure nobody gets hurt. We access the tree to remove anything at risk of falling and apply targeted reduction to try to mitigate the risk of further failures. This work happens immediately after a storm – as soon as it’s safe to do so.
Second, we need to give the tree time to react and recover.
This means stepping back for 1-2 growing seasons. During that time we want to watch what the tree is doing to compensate for the damage. It may send up countless epicormic shoots, or “watersprouts” in an attempt to add leaf area and sugar production. It may choose to discard entire sections of the canopy where it decides the cost of repairing a branch is greater than the cost of losing it. During the second phase of restoration, we might only do ground-based inspections or remove hazardous dead wood if it appears. This work is spread out over the first couple of years after a storm.
Third, we manage what’s left of the canopy to help steer it into what will be the tree’s new form.
In the 3rd year and subsequent years thereafter, we manage sprouts by removing some, reducing some, and retaining some undisturbed. Sprouts are the tree’s attempt to recover photosynthetic potential, but they are weakly-attached and generally very crowded, so they require judicious management to avoid a dangerous situation in years 7 and beyond. The sprouts of stress-response will eventually become the new canopy of a damaged tree, so we must walk a delicate tightrope between allowing the tree to recover naturally and removing material to steer it toward a stronger future. This work happens every 2 years from year 3 until we deem the restoration a “success”!
Restoration Pruning is a long-term commitment. Rebuilding a tree’s canopy after catastrophic damage requires training, forethought, restraint, and above all PATIENCE!
Ornamental, Fruit Tree, Espalier, and Bonsai
Smaller trees and those in unique situations can be treated differently to the way we prune large-statured species. Cypress brings a meticulous eye to disciplines such as bonsai, espalier, and “working tree” pruning.
Ornamentals such as Hawthorn and Redbud are highly aesthetically pleasing and sometimes benefit from pruning to accentuate their unique growth habits while improving their resilience under snow loading. Ornamental pruning requires a careful hand and an artful eye – it can be quite a creative process within the constraints of physics and tree biology!
Fruit Trees
Fruit Trees can be treated as ornamentals or as “Working Trees,” pruned to improve fruit production, strength under fruit load, and ease of harvesting. The kind of form we encourage in a working tree usually bears little resemblance to the form we encourage in a large tree. We might steer a tree into an open “vase” form to maximize light penetration for fruit ripening. We could choose to reduce the upper portion of the tree aggressively, maintaining a low height to keep you off of ladders when harvest time comes! Working tree pruning has everything to do with human desires. As long as we prune within what the tree’s health can sustain and we start with a young tree, the sky’s the limit (metaphorically speaking).
Espalier
Espalier is a highly-specialized pruning technique designed for fruit trees and ornamentals in tight spaces. It was developed during WWII in the blitz, when urban families needed to do everything they could to produce fruit in their small backyard spaces. Espalier involves planting a tree against a building or fence and then pruning so the tree grows mere inches from the wall. Growth away from the vertical surface is discouraged, and the tree is trained to grow along that surface. Espalier can be a way to grow sensitive species like cherry that might benefit from a little radiant heat. It’s a creative, aesthetic way to keep ornamentals in tight spots. The thing to remember about Espalier is that it’s intensive. We recommend annual pruning visits at a minimum to encourage the proper form over time!
Bonsai
Bonsai, like Espalier, is an intensive pruning process aimed at producing a twisted, aesthetic form. In the outdoor landscape, that aesthetic is applied to larger trees, rather than the pot-bound traditional bonsai you might have seen. Bonsai in the landscape is most often applied to evergreens like Juniper or Pine, as they lend themselves to the desired form. It can be a way to keep a large-statured tree in an area with height restrictions, or it can be used to beautify ubiquitous Fitzer Junipers and their ilk!
Safety Pruning/Retrenchment
Mature trees can sometimes go through periods of “retrenchment” in response to stressors. Root death, pathogens, pests, drought, and even progressive decay can lead to accumulation of dead material in the canopy. Sometimes, especially with aging trees, the only work that’s necessary or prudent is to clear the tree of hazards that might impact people or property.
When we look at a mature tree, we must consider preserving its considerable environmental benefit. Mature trees produce more oxygen, sequester more carbon, and play host to more species and individuals of wildlife than their younger counterparts.
Preserving mature trees means maintaining as much photosynthetic potential (leaf area) as possible while mitigating risks to people and property. That means taking very few live-tissue cuts, focusing instead on large-diameter dead wood removal.
If the tree has major defects we’re aware of, we might aggressively mitigate the resulting weakness with severe reduction to avoid catastrophic failures that might push the tree further into decline or even kill it.
Pruning for retrenchment is different from typical structural pruning, and is a rewarding manifestation of tree preservation.
Removals
Cypress Arboriculture is unflinchingly dedicated to preserving trees wherever possible, but sometimes a tree presents a risk to people or property that can’t be mitigated. A tree may have been planted or volunteered in the wrong space for its eventual size, may no-longer be compatible with a changing use of its site, or it may have simply declined due to disease, damage, environmental factors, or cultural changes. In that case, precise and thoughtful removal becomes necessary.
Cypress is equipped to handle small to medium sized tree removals. Trees up to approximately 15” in diameter are within our wheelhouse.
For larger trees requiring cranes or other equipment, we are happy to provide consultation services or simply a referral to one of our partner companies that specializes in larger-scale work.
As a cradle-to-cradle company, we believe a tree deserves dignity and a fresh existence even after its removal. For smaller trees that might mean recycling into mulch or use for firewood. For larger trees, it can mean something far more long-lasting and meaningful. In his book The Soul of a Tree, famed designer George Nakashima describes the second life afforded to salvaged trees. Cypress aims to support that second life. We partner with local Denver sawmill and furniture maker Where Wood Meets Steel to salvage larger logs for use in projects from cabinets to dining tables to bar tops and beyond!