Have you noticed that some older trees in your neighborhood are struggling or dying? Many College Park residents are concerned about the loss of mature trees, for good reasons. Older trees provide environmental, economic, and aesthetic benefits to our community. There are steps you, as a homeowner, can take to help protect your mature trees so future generations can enjoy their shade, beauty, and ecological value.

Why Older Trees Matter

As trees age, they grow more slowly and reach their maximum height and canopy size. Their roots spread outward, making them sensitive to changes in the environment. The age at which a tree matures depends on its species and growing conditions. For example, White Oaks (Maryland’s state tree) reach maturity around 80 years old and can live for centuries, while many maples mature earlier and live about 100 years. Maryland’s Wye Oak was once the largest White Oak in the United States with a 31’8” circumference before it succumbed to a severe thunderstorm on June 2, 2002. Some tree species are quite amazing in that no other living thing on earth is as successful at a long life.

As trees mature they show signs of age, such as cavities, dead branches, exposed wood, fungi, and sap flow. These conditions are not necessarily negative. In fact, they support biodiversity, by providing microhabitats for numerous species, including birds, insects, and bats.

Large, mature trees also play a key role in mitigating climate change, storing carbon, producing oxygen, and cooling the air and our homes by providing shade. Their extensive root systems stabilize soil, reduce erosion, and help filter stormwater, protecting nearby streams and waterways.

Beyond environmental benefits, older trees add economic value. Homes with healthy, mature trees tend to sell faster and at higher prices, and neighborhoods with more tree cover are often more desirable. Mature trees also enhance curb appeal, framing homes with lush greenery in spring and summer and vibrant color in the fall.

How You Can Help Protect Older Trees

Because older trees are so valuable, caring for them is a worthwhile investment. Key steps include watering, mulching, pruning, sometimes fertilizing roots, sometimes cabling, and monitoring overall health.

Watering:

During dry periods, older trees can benefit from watering every two to three weeks. Of course, if under drought conditions, watering more often is warranted. Place a hose or drip system in a circle around the tree at the edge of the canopy, water slowly so moisture reaches a depth of 12-18 inches; then let the soil dry before watering again. This encourages deeper roots and improves drought resistance. If you are concerned about water costs, install an exterior sub-meter, which will allow you to water without paying sewer charges.

Mulching:

Mulching large trees is not absolutely necessary because they have large spreading root systems. However, mulch can help retain soil moisture and reduce weed growth. If you are mulching apply 2”-3” of clean fresh mulch, not touching the tree’s bark. Keep in mind that excessively high mulch applications up against a tree (called volcano mulching) can lead to decaying mulch and then tree decay. Therefore, avoid installing too much mulch.

Pruning:

Over time some branches naturally die which is often due to shading from the upper branches. If not pruned these dead branches typically break off during high wind events. Removing dead, damaged, or diseased branches can help keep older trees safe and healthy and prevent damage to your property. However, pruning without a good reason should never be done. Pruning 10-15% of live branches on the crown is about the maximum recommended. Since pruning live branches reduces the amount of leaf surface it is reducing the capacity of the tree to produce sugars and nutrients. This would not be the case pruning dead branches. Creating a pruning cut exposes part of the interior of the tree and creates a potential entry point for pathogens until the tree seals over it. It takes a long time for a tree to seal over a pruning cut with response wood. Because large trees can be hazardous to prune, especially near power lines, this work should be done by a Maryland licensed tree expert.

Deep Root Fertilization:

Deep root fertilization is a practice often performed on trees which have suffered root loss due to construction damage. This treatment delivers nutrients directly into the root zone with a wand pushed into the soil. The practice helps the tree regenerate new root growth. Typically, large trees don’t need fertilizer added to the soil. Applying too much fertilizer can be detrimental to trees and plants by negatively modifying the soil chemistry. If you have a question consult a professional arborist or tree expert who does soil testing to determine if this treatment is needed.

Air Spading:

Air spading is the practice of using high pressure air to aerate and de-compact soil within a tree’s root zone. This is definitely highly beneficial particularly for mature trees. Over many

years soil and mulch within a root zone can become compacted which reduces the root system. Unfortunately, this is an expensive practice and may cost several thousand dollars per tree.

Cabling:

Cabling is typically done to increase the structural integrity of a tree’s branch or fork. Cabling branches in older mature trees is a typical practice and sometimes reduces the amount of pruning necessary.

Monitoring Tree Health:

Keep an eye out for signs of stress or decline, including wilting leaves, early leaf drop, thinning canopies, cracked or peeling bark, and dead branches. Older trees can be affected by storms, flooding, drought, extreme temperatures, pests, and disease. Unfortunately, many older trees in College Park have succumbed to root disease which is typically fatal. Early attention may make a big difference.

An Investment in our Community

Older trees are one of College Park’s greatest assets. By watering, mulching, pruning, monitoring, and seeking professional advice from a licensed tree expert when needed, you can help protect your trees and benefit from their value. Caring for older trees is not just good stewardship, it’s an investment in the health, beauty, and resilience of our community.