Sherida Phibbs, UC Master Gardener
Recently, my quiet neighborhood became an unintended classroom in what not to do with trees. In a short time, several neighbors made choices that seriously harmed mature trees—whether by topping, removing, or poorly pruning them. Watching these beautiful shade trees lose half their canopy or disappear altogether was heartbreaking. It’s a reminder that while trees grow slowly over decades, they can be damaged in moments, sometimes unknowingly.
This article aims to share key insights about common mistakes homeowners make in caring for their landscapes. With a better understanding, anyone can avoid these frequent errors and help their trees thrive, adding lasting beauty and value to their homes.
The Danger of Topping
Topping—cutting off large portions of a tree’s upper branches—is one of the most damaging pruning mistakes. Though often done to control size or reduce risk, it actually weakens tree structure and invites long-term problems. Topped trees respond by sending out water sprouts: fast-growing but fragile branches prone to breaking. Large wounds also reduce energy reserves and invite decay. The better alternative is crown reduction or selective structural pruning, which keeps trees healthy and stable. If pruning is intimidating, consider hiring a certified arborist. Learn more: Topping Trees Is Harmful
Avoid Over-Pruning
Removing more than 25% of a tree’s canopy in one year severely stresses it. Over-pruned trees expend vital resources growing weak new shoots and become vulnerable to storm damage and disease. Pruning should focus on removing dead or crossed branches and maintaining structural integrity—not just thinning. Learn more: Overpruned Trees
Planting at the Right Depth
Planting too deep is a silent killer of many new trees. When the root flare is buried beneath the soil, roots can suffocate or circle the trunk, slowly strangling the tree. To avoid this, plant so the root flare is visible above the soil surface. Learn more: Proper Tree Planting and Tree Planting Notes
Protect the Trunk Zone
Planting flowers or shrubs too close to a tree’s trunk traps moisture, damages bark, and restricts necessary air exchange. Maintaining a 12- to 18-inch clear zone around the trunk and spreading mulch lightly (without piling it against bark) protects the tree’s health. Learn more: Underplanting Trees
Water Wisely
Watering at the base of the trunk does little good, as most absorbing roots extend well beyond the canopy edge. Water deeply and slowly in a ring just outside the drip line to effectively hydrate the root system and reduce disease risk.
Learn more: Preparing Trees for Winter and Proper Irrigation Practices
Skip Landscape Fabric
Although tempting to use as a weed barrier, landscape fabric restricts air and water movement to roots, leading to shallow, stressed root systems and poor soil health. Organic mulch is a better choice, allowing the soil to breathe and support microbial life. Learn more: Disadvantages of Landscape Fabric
Prune at the Right Time
Proper timing is key to pruning success. Pruning spring-blooming shrubs in winter removes their flower buds, and late-season pruning encourages tender growth vulnerable to frost. Generally, prune spring bloomers right after they have finished flowering, and summer bloomers in late winter or early spring. Pruning should never be done in the summer for most trees and shrubs. Learn more: Fall Pruning
Make Proper Pruning Cuts
Cut branches just outside the branch collar using the three-cut method to avoid tearing the bark. Proper cuts help the tree heal quickly and ward off decay; wound sealants are unnecessary. Learn more: Pruning Cuts
Avoid Volcano Mulching
Mulch piled high against a trunk holds moisture against the bark, causing rot and inviting pests. Spread mulch to 3 to 4 inches deep, keeping it several inches away from the trunk for healthy growth. Learn more: Proper Mulching
Care for Young Trees
Newly planted trees need regular, deep watering and occasional staking for the first 2 to 3 years to establish strong roots and trunks. Remove stakes as soon as the trees can support themselves. Learn more: Training and Pruning Young Trees
Space Plants Properly
Crowded plants compete for nutrients, reduce airflow, and increase disease risk. Space plants according to their mature size, not container size, for long-term success. Learn more: Give Landscape Plants Proper Space
Don’t Neglect Soil Health
Healthy soil is vital for thriving plants. Compacted or nutrient-poor soil restricts root growth and microbial activity. Promote soil health with organic mulch, compost, and gentle cultivation around roots. Learn more: Soil Health
Final Thoughts
Mistakes in the garden are part of the learning process, but repetitive errors are costly. Trees and shrubs not only beautify neighborhoods but also cool homes, clean the air, and support wildlife. Attentive care—right planting depth, thoughtful pruning, proper watering, and mulch management—can nurture healthy landscapes for decades. Understanding plants’ natural rhythms and needs, rather than trying to control them, creates resilient, thriving gardens.