Tree pruning is pretty simple, right? You just walk up to a tree with some clippers and start hacking. Not so fast – there are in fact, many types of tree pruning as there are reasons your trees need to be pruned. Here’s an overview of why it’s important to prune trees.
To mitigate risk
- Prune to lower the likelihood of tree, branch, and/or other tree part failure and impact to targets.
- Reduce or remove branches (living and dead) and/or other parts that pose an unacceptable risk of failure.
- Reduce the length of branches or leaders to reduce load.
Additional information
In addition to pruning, consider supplemental support if appropriate.
To manage health
- Prune to improve or maintain plant health, or control pests.
- Remove deleterious parts, e.g. dead or dying branches, diseased or infested branches, rubbing, weakened or broken branches, parasitic plants, etc.
- Take appropriate precautions when necessary to prevent the spread of pests, e.g. seasonal timing of work, sterilization of tools, handling/disposal of debris/by-products.
To develop or improve the structure
- Prune to improve plant architecture (i.e. desirable branch size, spacing, diameter and aspect ratios), ensure that the plant is compatible with the site (e.g. minimize conflict with traffic, sightlines or infrastructure), and/or to restore damaged plants. Initiation of structural pruning early in the life of the plant can enhance benefits and value, and reduce long-term maintenance costs and potential for failure.
- Select dominant leader(s) and desirable scaffold branches for development as appropriate for the species and site.
- Subordinate or remove competing leaders, branches, and shoots. If necessary, subordinate larger branches over multiple growing seasons to avoid making cuts with large aspect ratios.
- Avoid removing an excessive amount of living material at any one time.
Restoration pruning
Prune to redevelop or improve structure, form, and appearance following damage from storms, vandalism, lion tailing, topping or other substandard pruning, or other causes.
Specification
- Assess trees for risk if necessary prior to beginning restoration pruning.
- Retain suitable leaders, branches, and shoots to be developed.
- Reduce, subordinate and/or remove competing or undesirable parts.
To provide clearance
- Prune to prevent interference with infrastructure, buildings, traffic, lines-of-sight, desired views, or other plants; also to ensure safe and reliable utility services, raise crowns, provide access to sites, and comply with regulatory and other requirements as necessary.
- Use directional pruning to encourage growth away from the specified clearance area and to develop a compatible and stable structure.
- Avoid removing an excessive amount of living material at any one time.
To manage the size and/or shape
- Prune to reduce the size or maintain desired shape (consider species and typical form, ability to tolerate the amount of pruning required, location, current condition, and other characteristics such as cultivar, failure profile, growth rate and expected growth response following pruning).
- Selectively reduce or remove branches, leaders or other parts to achieve or maintain the desired form, shape or size, or to encourage regenerative growth from lower parts of the tree.
- Avoid removing an excessive amount of living material at any one time.
Retrenchment (Regenerative) pruning
- Perform retrenchment pruning to preserve and maintain trees in the landscape, especially those of high value or special heritage. Retrenchment is a natural process whereby older trees gradually shed overextended, decayed, damaged, or declining branches and leaders, and redirect energy into epicormic growth from interior and lower portions of the crown. Depending on species and site conditions, this process may occur over many years, decades or centuries.
- Retrenchment pruning mimics the natural process of retrenchment by making prescriptive pruning cuts to remove declining branches, reduce the risk of failure, stimulate new shoots on interior and lower branches, and restore tree vitality and appearance. Resulting in new growth is subsequently managed to guide future structural development. Arborists should consider whether retrenchment pruning is appropriate, considering factors such as species, condition, placement, aesthetics, and expected response.
Specification
- Selectively reduce, remove or head branches that are dead, senescing, damaged, or that pose an unacceptable risk.
- Minimize the size of cuts on living wood whenever possible (preferably less than 6” in diameter).
- Maintain and monitor suitable branches or leaders that are healthy and do not pose an unacceptable risk.
To improve aesthetics
- Prune to improve the visual appearance of plants and/or the surrounding site.
- Selectively reduce or remove branches, leaders or other parts to achieve aesthetic objectives.
To manage production
- Prune to optimize production or desired characteristics of fruit, floral, timber, canes or other products. Selectively remove branches or other parts to achieve desired production levels.
- Consider seasonal timing of pruning, as well as species and cultivar characteristics.
Rejuvenation of Shrubs
- Prune to stimulate new growth, restore the desired form, and/or to remove dead, damaged, diseased or infested parts (consider species and typical form, current condition, seasonal timing, and ability to tolerate rejuvenation pruning).
- Reduce or head branches or leaders at or near ground level.
To manage Wildlife Habitat
- Prune to conserve or enhance wildlife habitat.
- Manage wildlife habitat: Pruning activities may influence wildlife, either directly through disturbance, or by manipulation of habitats such as food supplies, cover, nesting or roosting sites. Pruning activities may violate certain regulations. Arborists should modify work procedures as appropriate to avoid killing, injuring or disturbing protected wildlife.
- Pruning to improve or manipulate wildlife habitat may be part of an overall strategy across an entire property, park, right-of-way or other management areas. The practice may involve multiple pruning objectives, pruning systems and other strategies beyond the scope of a pruning standard.
- Prune to stimulate growth, cover, fruit or seed production.