Why Arborvitae Are Popular — And Why They Sometimes Struggle

Arborvitae (genus Thuja) are one of the most widely planted evergreens in Michigan landscapes. Their tall, dense foliage makes them natural choices for privacy screens, hedges, or foundation plantings. Many home gardeners favor cultivars like Green Giant, American Pillar, or Emerald Green for their upright growth and year-round greenery. (Better Homes & Gardens)

Despite their popularity and general hardiness in USDA Zones 3–7—zones that include Southeast Michigan—arborvitae are not trouble-free. Homeowners frequently encounter issues with insects, environmental stress like winter burn or drought, and watering challenges. Let’s break down the most common problems you’ll see here in and around the Trenton/Detroit area.

1. Insect Problems That Bite and Bore

Although arborvitae aren’t as pest-prone as some plants, several insects can seriously damage them if not caught early:

Bagworms

Bagworms are among the most destructive pests you’ll find on arborvitae. Their caterpillars form distinctive silken bags that hang from branches — often resembling small pine cones. The larvae feed on foliage from inside these protective bags, leading to defoliation and thinning canopies over time. (Yardener Gardening)

Signs of bagworms:

• Spindle-shaped bags on branches
• Gradual browning and thinning foliage
• Damage typically visible in late summer

Control tips:

• Remove bags by hand in spring and early summer before larvae mature.
• In heavy infestations, consider Bacillus thuringiensis (Bt) or insecticides timed to larval stages.

Spider Mites

Spider mites are tiny sap-sucking arthropods that thrive in hot, dry spells. Although they’re microscopic, their effects are visible: foliage becomes stippled or bronzed, fine webbing may appear, and overall tree vigor declines.(Yardener Gardening)

What to watch for:

• Fine webs on branch interiors
• Dull or dusty-looking foliage
• Small speckled damage on needles

Management:

• Spray with a strong stream of water to knock mites off.
• Use insecticidal soaps or horticultural oils (avoid application in extreme heat).

Other Insects and Pests

Arborvitae can also be affected by:

• Scale insects — small, shell-covered sap feeders causing yellowing or weakening foliage. (Yardener Gardening)
• Aphids — suck sap, distort foliage, and encourage sooty mold. (Yardener Gardening)
• Borers and cedar bark beetles — tunnel into wood, especially on stressed trees. (Burkholder Plant Health Care)
• Deer and rodents — chew branches and bark, especially when other food is scarce. (Biology Insights)

One practical tip many gardeners find helpful: regularly inspect your arborvitae during the growing season — especially on the interior of hedges where pests hide. Early detection makes treatment easier.

2. Winter Damage: The Silent Evergreen Killer

Southeast Michigan winters — with fluctuating temperatures, dry winds, and reflective sunshine off snow — can take a toll on arborvitae. Here are the main winter stressors to watch for:

Winter Burn / Desiccation

Arborvitae lose moisture through their foliage even in winter. However, once the ground freezes, roots can’t take up water to replace what’s lost. When this desiccation occurs due to wind and sun, the foliage turns brown or bronze — often most noticeable on the south and west sides of the tree.(Deer Solution)

Symptoms:

• Browning without obvious insect signs
• Lopsided damage on exposed sides
• Loss of needles come spring

Preventive strategies:

• Water deeply in late fall before the ground freezes — this supplies the roots with moisture for winter. (Nature Hills Nursery)
• Mulch with 2–3 inches of organic material to insulate roots and reduce moisture loss. (Nature Hills Nursery)
• Consider wrapping young or exposed trees with burlap or windbreaks to reduce drying winds.

Heavy Snow and Ice Load

Arborvitae branches can splay or break under heavy snow and ice weight, especially upright varieties. When branches bend or break, the plant’s silhouette and screening ability suffer — and some plants never regain their former shape.(Homes and Gardens)

Pro tip: After snowstorms, gently brush snow off branches with a broom to reduce weight load.

Road Salt Injury

Plantings near driveways or streets may show signs of salt burn. Salt spray in winter or runoff into soil can damage roots and foliage, leading to browning and reduced growth.(New York Botanical Garden LibGuides)

Plant arborvitae away from direct salt exposure areas, and use barriers if necessary.

3. Watering Woes: Too Little or Too Much Can Hurt

Water management is one of the most important aspects of arborvitae care — yet it’s where many growers go wrong.

Underwatering / Drought Stress

Arborvitae have moderately shallow roots and rely on consistent soil moisture. In hot, dry summers or during prolonged dry spells, insufficient water causes browning foliage, wilting, and dieback — usually starting at the tips and moving inward.(Biology Insights)

Signs:

• Wilting, dull or grayish foliage
• Browning begins at the top or outer edges

Watering tips:

• Water deeply and infrequently rather than shallow watering.
• Use soaker hoses or drip irrigation during dry periods.
• Newly planted arborvitae need more regular watering until established.

Overwatering / Root Rot

Ironically, too much water is also a problem. Poor drainage and consistently wet soils deprive roots of oxygen and can lead to root rot — a fungal condition that weakens the tree and causes yellowing, wilting, and eventual decline.(Envirevo Agritech)

Avoid overwatering by:

• Planting in well-drained soil
• Avoiding heavy clay areas without amendment
• Allowing the top inch of soil to dry slightly between waterings

4. Diseases That Can Hide Behind Browning Foliage

Although Michigan’s climate doesn’t make arborvitae disease hotspots, fungal diseases can still occur, especially in wet spring or humid summers:

• Needle blights and leaf spot — fungi that cause brown spots or premature needle shed.(Farmonaut)
• Cankers and twig blights — cause dieback and brown lesions on branches.(Envirevo Agritech)

Healthy arborvitae with good air circulation and proper watering are much less susceptible. If disease is suspected, prune out affected parts and improve drainage or air flow.

5. Practical Care Tips for Southeast Michigan

Here are helpful, region-specific tips to prevent and manage most of the issues above:

Plant in the Right Spot

Choose a location with:

• Full sun to partial shade
• Well-drained soil
• Good air circulation to reduce fungal risk

Mulch and Water Strategically

• Apply a 2–3″ layer of mulch around the base (not touching the trunk).
• Water deeply: newly planted trees weekly in dry spells; established ones during droughts.

Inspect Regularly

• Check for pests like bagworms, spider mites, and scale at least once a season.
• Inspect leaves inside the canopy — pests often hide away from casual view.

Winter Prep Matters

• Deep water before ground freeze (usually late October–November).
• Use burlap shields or windbreaks for young or exposed plants.
• Gently brush heavy snow off branches after storms.

Deer & Wildlife Protection

If deer are common in your area, consider repellents or fencing — deer damage can be abrupt and extensive, particularly in winter.(Biology Insights)

Conclusion

Arborvitae are stunning landscape evergreens, but in Southeast Michigan they face a unique set of challenges — from winter winds and salt spray to insect pests and watering issues. Recognizing the signs early and understanding the underlying causes can make the difference between a healthy hedge and a line of stressed or dying evergreens.

With thoughtful planting, consistent watering, and proactive care, your arborvitae can thrive and provide year-round beauty in Michigan landscapes. And if you ever find yourself wondering “what’s wrong with my arborvitae?” — take a close look at insects, winter care, and soil moisture first. They’re often the most common culprits.