If you’ve noticed brown needles, thinning branches, or dead patches forming in your evergreens, you may be asking, why are my hemlock trees dying Hemlocks are a common and iconic part of the landscape in Snohomish County, but they are also vulnerable to a number of pests, diseases, and environmental stresses. At Snohomish Tree Company, we help homeowners understand what’s happening and what you can do to protect or remove these trees safely if needed.
1. Hemlock Woolly Adelgid Infestation
The most destructive threat to hemlock trees is a tiny insect called the woolly adelgid. This invasive pest attaches to the underside of needles, feeding on sap and slowly killing the tree. One clear sign of their presence is a white, cotton like substance near the base of the needles. Over time, the tree loses vigor and may die within a few years if untreated.
2. Root Rot and Fungal Disease
Hemlocks prefer moist, well drained soil. Poor drainage or excess watering can promote fungal growth around the roots, leading to root rot. Once the root system is damaged, the tree struggles to take in nutrients and may show yellowing or browning from the bottom up. This is a common issue in low lying areas of Everett, Monroe, and Lake Stevens.
3. Drought Stress and Environmental Changes
Even though Western Washington is known for its rain, hemlocks can suffer during dry summers or in areas with compacted soil. Drought conditions weaken the tree, making it more susceptible to insects and disease. You may notice needles dropping prematurely or sparse foliage at the crown during prolonged dry spells.
4. Damage from Construction or Soil Disruption
If you’ve recently done any home construction, landscaping, or trenching near the base of a hemlock tree, the root system may have been disturbed. Even cutting roots on one side of the tree can cause imbalance, slow decline, or vulnerability to pests. This is especially common in developed areas like Lynnwood, Mountlake Terrace, and Mukilteo where new construction is common.
5. Natural Aging and Competition
Sometimes, hemlocks decline due to age or competition for sunlight, water, and nutrients. In overgrown yards or forested lots, younger trees can become overcrowded. Hemlocks that were once dominant may begin to show signs of stress as they compete for limited resources.
What to Do if Your Hemlock Tree is Declining
Our team at Snohomish Tree Company offers on site evaluations throughout Snohomish County including Gold Bar, Granite Falls, Arlington, Darrington, and Silvana. If you suspect your hemlock is infected or dying, we’ll assess the condition and provide expert recommendations.
In some cases, treatment with insecticides or systemic injections may help save the tree. In other situations, removal may be necessary to prevent collapse or the spread of disease to nearby trees.
We Offer the Following Tree Services
- Tree Pruning to help reduce stress on damaged trees
- Tree and Forest Thinning to reduce overcrowding
- Wind Sailing for stronger wind resistance
- Stump Grinding after removal
- Fixing Leaning Trees before failure occurs
See the Quality of Our Work
We invite you to browse our project gallery to see before and after photos of trees we’ve saved, removed, or helped maintain throughout the Snohomish County area. You can also read our customer reviews to learn why homeowners trust our knowledge and honesty.
Schedule an Expert Evaluation Today
If you’ve been wondering why are my hemlock trees dying, don’t wait until the problem becomes dangerous. Contact Snohomish Tree Company for a local, professional diagnosis and a clear plan of action. Contact us or request a free estimate anywhere in Snohomish County.
