Why Are My Arborvitae Leaves Turning Brown?

Arborvitae leaves turn brown for several common reasons, including winter burn, pests, diseases, or improper watering. Identifying the specific cause is the first step to saving your shrubs and keeping them healthy. Below, find practical answers to the most frequent questions about browning arborvitae.

What Causes Arborvitae Leaves to Turn Brown?

Several factors can cause arborvitae foliage to turn brown. The most common include winter burn from cold winds and sun, drought stress from too little water, root rot from overwatering, and pest infestations like spider mites or bagworms. Fungal diseases such as needle blight can also cause browning. Often, the problem starts at the tips or inner branches and spreads if not addressed.

To help you diagnose quickly, here is a simple checklist:

Possible Cause	What It Looks Like	What to Do
Winter burn	Brown tips, worst on south/west sides	Water deeply in fall; wrap in burlap
Drought	Brown from bottom up, crispy leaves	Water 1–2 inches per week
Overwatering/root rot	Yellowing then brown, mushy roots	Improve drainage; reduce watering
Pests (spider mites, bagworms)	Speckled or chewed leaves, webbing	Apply insecticidal soap or remove bags
Fungal disease	Browning at base or in patches, cankers	Prune affected areas; apply fungicide

Always check the surrounding soil moisture and look for signs of insects or disease before deciding on treatment.

How Do I Know If It's Winter Burn?

Winter burn is very common in arborvitae, especially in areas with cold winters and bright sun. It happens when evergreen leaves lose water faster than roots can replace it from frozen soil. The browning usually shows up in late winter or early spring on the side facing the sun or wind.

Signs of winter burn include:

Brown or reddish tips, especially on south or west sides
Only the outer foliage affected; inner branches stay green
No signs of insects or fungal spots
Damage appears after a dry, windy period

To prevent winter burn next year, water your arborvitae deeply in late fall before the ground freezes. You can also wrap the shrubs in burlap or use an anti-desiccant spray. If winter burn has already happened, wait until new growth appears in spring, then prune only the dead tips with clean shears.

For deep watering, a quality water hose nozzle with adjustable settings makes it easy to deliver a slow, steady soak around the root zone.

Can Pests Make My Arborvitae Turn Brown?

Yes, pests are a frequent cause of browning. The most troublesome are spider mites and bagworms. Spider mites are tiny, but you can see fine webbing on the branches. They suck sap from leaves, causing a speckled, yellow-brown look. Bagworms are caterpillars that build protective bags from foliage; they eat needle tips, turning whole branches brown.

Other pests include scale insects (look like small bumps on stems) and arborvitae leafminers (tunnels inside leaves, causing browning tips).

What to look for:

Tiny webs between leaves (spider mites)
Small, cone-shaped bags hanging from branches (bagworms)
Sticky residue or black sooty mold (scale)
Lots of small, brown tips (leafminers)

For spider mites, a strong blast of water can knock them off, or use an insecticidal soap. For bagworms, simply pick off the bags and dispose of them. An effective ready-to-use insecticidal soap spray works well for mites and scale when applied every 7–10 days.

What Diseases Cause Brown Leaves on Arborvitae?

Several fungal diseases can turn arborvitae leaves brown. Needle blight (often caused by the fungus Pestalotiopsis) is common. It starts on lower branches and spreads upward, with brown spots or bands on needles. Tip blight causes brown tips with tiny black fungal fruiting bodies. Root rot (from Phytophthora or Armillaria) causes leaves to yellow, then brown, and the whole plant may wilt.

Signs of disease:

Browning begins on inner or lower branches
Black spots or cankers on stems
Needles fall off easily when touched
White fungal growth near base (root rot)

Most fungal diseases thrive in damp, poorly ventilated conditions. To treat, prune out infected branches using clean, sharp tools. Improve air flow by spacing plants properly. If needed, apply a fungicide labeled for arborvitae. For pruning, a reliable set of bypass pruning shears gives clean cuts that help prevent disease spread.

How Does Watering Affect Arborvitae Leaves?

Both too little and too much water can turn arborvitae leaves brown. These shrubs need consistent moisture, especially the first two years after planting. During dry spells, leaves lose turgor, start to curl, and then turn brown, starting from the bottom upward. On the other hand, overwatering or planting in heavy clay soil can suffocate roots, causing yellowing, then browning, and often root rot.

The right approach:

Water deeply once a week during dry periods (1–1.5 inches of water)
Use a soaker hose or drip irrigation to avoid wetting foliage
Check soil moisture 2–3 inches deep – if dry, water; if soggy, wait
Mulch around the base (2–3 inches deep) to keep soil cool and moist

If you are unsure whether your arborvitae is getting enough water, a simple soil moisture meter can take the guesswork out of watering schedules.

Should I Prune Brown Leaves Off My Arborvitae?

Yes, but only after you have identified the cause and treated it. Pruning brown leaves helps the plant look better and prevents disease from spreading. However, never cut into bare wood – arborvitae do not regrow from old, leafless stems. Only remove the brown tips or affected branches back to where green growth remains.

Best practices for pruning:

Wait until early spring (after last frost) to cut back winter damage
Use sharp, sanitized shears to avoid crushing stems
Cut just above a live bud or side branch
Do not prune more than one-third of the plant at a time

If you see signs of fungal disease, disinfect your shears between cuts with rubbing alcohol. Regular pruning also improves air circulation, which reduces future disease.

How Can I Prevent Arborvitae From Turning Brown Next Year?

Prevention is easier than treatment. Follow these steps to keep your arborvitae green and healthy:

Water wisely – deep watering in fall before ground freezes; consistent moisture in summer.
Mulch – 2–3 inches of bark mulch around the base (not touching the trunk) to conserve moisture and insulate roots.
Protect from winter wind – wrap with burlap or install a windbreak for exposed shrubs.
Space properly – allow room for mature size to ensure good air flow.
Monitor for pests – check monthly for webbing, bags, or sticky residue.
Prune annually – remove dead branches in early spring to promote health.

Also, choose disease-resistant arborvitae varieties (like ‘Emerald Green’ or ‘Green Giant’) if you are planting new ones. A little routine care goes a long way toward avoiding the frustration of brown leaves.

When Should I Call a Professional?

If you have tried the basics – adjusted watering, checked for pests, pruned dead parts – and the browning continues or spreads rapidly, it is time to call an arborist or plant health specialist. Professional help is especially needed if:

More than half the plant turns brown in one season
You see cankers, oozing sap, or mushroom growth at the base
Multiple plants in your landscape are affected
Root rot is suspected (mushy roots, foul smell)

A professional can take soil samples, identify specific pathogens, and recommend treatments like fungicide drenches or soil amendments that are beyond typical home remedies.