Can You Keep Outdoor Lights on Trees Throughout the Year?

Twinkling lights wrapped around trees can make any yard look great. But can your trees handle being lit up like a Christmas tree all year long?

Technically, they can. But (and yes, of course, there’s a but) long-term use of tree lighting can have unintended consequences if not done properly.

Before you commit to year-round illumination, let’s explore when it’s safe when it’s risky, and how to keep your trees safe and your lights shining bright.

When Keeping Lights Up Is Safe

When You Use Tree-Friendly Installation Methods

Ditch the nails and staples. Piercing the bark can introduce infections and stress the tree. Instead, use soft ties, clips, or wrap-around hooks that won’t damage the bark.

Wrapping lights too tightly around branches can restrict growth, causing long-term damage. Leave some slack to accommodate natural expansion. Also, avoid wrapping around the trunk. Keep lights on the outer canopy to reduce stress on the tree’s main structure and allow for proper air circulation.

When You Select the Right Lights

• LEDs over incandescent: LED lights emit less heat, reducing the risk of bark damage and fire hazards. They’re also energy-efficient and last longer.
• Solar-powered or battery-operated lights: These eliminate the need for long extension cords, which can cause trip hazards and unnecessary strain on branches.
• Weatherproof and outdoor-rated: Not all string lights are made for year-round exposure to the elements. Make sure yours can handle rain, snow, and temperature fluctuations.
• Low-voltage lights: Reduce electrical risks by using low-wattage outdoor lighting, which is safer for both trees and people.
• Tangle-free design: Strings that are easy to detangle minimize installation time and prevent stress on branches when adjusting.

When You Select the Right Tree Type for Permanent Lighting

• Sturdy, mature trees with thick bark (think oaks, maples, and pines) handle lighting best. Their bark is more resistant to pressure and minor abrasions. Don’t hang lights on new-planted, young trees.
• Avoid lighting delicate ornamentals like birch and Japanese maple, as they have thin bark that can easily be damaged.
• Evergreens work well, but monitor them for moisture retention around the lights. Excessive dampness is a NO for them and encourages fungal growth.
• Trees adapted to the local climate tend to have stronger resistance to environmental stress, making them a better fit for permanent lighting.
• Climbing a ladder every season is risky, so it is best to pick trees that don’t require excessive height access for maintenance.

When Outdoor Lights Can Harm Trees

While outdoor lighting can enhance your yard’s appearance, improper installation or long-term use can create problems for your trees.

• Risk of Girdling: Trees don’t stay the same size forever! If lights are wrapped too tightly, they can cut into the bark over time, restricting the tree’s ability to transport water and nutrients. This is called girdling and can weaken branches and, in severe cases, even kill the tree.
• Moisture & Mould Issues: Keeping lights on trees year-round can trap moisture, especially in humid or rainy climates. Damp conditions encourage fungal growth, which can infect bark and weaken the tree’s structure. Certain tree species, particularly evergreens, are prone to excess moisture retention.
• Attracting Unwanted Pests: Warm light bulbs can attract insects, which may lead to infestations in trees or nearby structures. Additionally, small animals, like squirrels and rodents, may chew through wires, potentially harming themselves and your tree.
• Interference with Photosynthesis: Trees rely on natural light cycles, and excess artificial lighting at night can disrupt their dormancy and growth patterns. In fact, certain species may experience delayed seasonal changes if exposed to too much artificial light.
• Fire Risk in Dry Conditions: While rare, electrical malfunctions or overheating bulbs can pose a fire hazard in dry, hot seasons. This is especially true for older or non-LED lights that generate more heat.

Best Practices for Long-Term Tree Lighting

• Use clips or hooks instead of wrapping lights around branches, which can cut into bark and restrict growth.
• Keep light strings loose and adjustable so that they don’t cause girdling or damage.
• Avoid using nails or staples, as they puncture the bark and introduce potential infections into the tree.
• Choose weather-resistant fasteners that won’t degrade over time. Plastic clips and rubber-coated wire ties are great options for durability.
• Wrap lights around branches in a spiral pattern instead of looping them tightly, allowing for natural tree growth and movement.
• Position lights on sturdier branches rather than thinner, more flexible ones, which are more prone to breakage under added weight.
• Avoid crisscrossing multiple light strands over the same branches so as to minimize stress on any one part of the tree.
• Use outdoor-rated lights with insulated wiring to prevent electrical shorts caused by moisture buildup or fluctuating temperatures.
• Consider using detachable string lights that can be easily removed and replaced instead of permanent fixtures.
• Leave gaps between the lights and foliage to prevent excess heat from building up and drying out nearby leaves.
• Opt for solar-powered stake lights near the tree base if wrapping lights on branches isn’t ideal for tree health.
• Ensure lights are spaced evenly throughout the tree rather than concentrated in one area, preventing uneven weight distribution.
• Inspect lights seasonally to make sure they aren’t too tight, tangled, or causing damage. If heavy snow is in the forecast, remove lights from fragile branches to prevent breakage.
• Untangle and reposition lights if needed, especially in fast-growing trees where branches may shift over time.
• Use professional lighting services to install, remove, and help store your lights.

Alternatives to Year-Round Lighting

If you love the idea of keeping your outdoor space illuminated but want to avoid potential harm to your trees, there are plenty of alternatives that provide the same warm, inviting glow.

Ground-based lighting is a great option that enhances trees without direct contact. Uplighting or spotlights placed at the base of a tree can create a dramatic and elegant effect while keeping branches free from tangled cords.

Solar-powered stake lights along pathways or in flower beds can also provide subtle, ambient lighting that highlights your landscape year-round.

For a whimsical touch, consider hanging lanterns or string lights on pergolas, fences, or freestanding poles instead of wrapping them around trees. Bistro-style lighting strung between posts or across outdoor seating areas offers a cozy, café-like atmosphere without the risk of damaging tree bark.

Another option is using motion-activated lights that turn on only when needed. These provide security and visibility without extended exposure that can interfere with a tree’s natural growth cycle.

If you prefer a natural glow, consider fire features like tiki torches or solar-powered LED candles in outdoor lanterns. They provide warmth and ambiance without any impact on your trees.

Is It Time to Let Your Trees Breathe?

The holidays are long gone, and while your trees might not complain, they’re definitely ready to shed the extra weight. Leaving lights up throughout the year can do more harm than good, so if your tree is still shining brightly, perhaps it’s time to give it a break.

Need help assessing your tree’s health after winter and the impact of the hanging lights? Green Drop’s ISA-certified arborists bring you expert tree healthcare services across Calgary, Winnipeg, Edmonton, Red Deer, Regina, and Saskatoon.

Whether your trees need a trim, some upkeep, or a complete glow-down, we’ve got you covered. Schedule an assessment today, and let’s keep your trees thriving all year long!