How To Save Brown Arborvitae Trees In Summer
Seeing your once-green arborvitae turn brown in midsummer is heartbreaking. I’ve been there — those columnar evergreens that frame a yard or mark a property line suddenly look scorched and sparse. The good news is that many brown arborvitae can be saved when you act quickly and smartly. In this guide I’ll walk you through diagnosing the cause, practical immediate steps, treatment options, and prevention so your arborvitae come back strong next season.
First Step: Diagnose Before You Treat
Not all browning is the same. Spend a few minutes inspecting the tree to figure out whether the issue is drought, pests, disease, salt or winter damage resurfacing in summer.
Quick checks I always do
- Pull back a small patch of foliage and scratch the inner bark — green means live, brown and brittle means dead.
- Feel the soil 3–4 inches down near the root zone — bone dry, soggy, or somewhere in between?
- Look for pests, webbing, or chewed foliage along branches and at branch bases.
- Check nearby pavement and roads for salt exposure, and observe planting depth and mulch level.
That initial diagnosis tells you whether to water, prune, treat for pests, or call in help.
Common Causes of Summer Browning and How to Fix Each One
Drought and Heat Stress
This is the most common summer culprit. Arborvitae have shallow roots and need consistent moisture when temperatures spike.
- Deep soak once or twice weekly rather than frequent shallow watering. Aim for 1–2 inches of water per week including rain.
- Use a soaker hose or slow trickle at the base for 45–60 minutes so water penetrates 8–12 inches deep.
- Water early morning to reduce evaporation.
- Mulch 2–3 inches of organic mulch out to the dripline, but keep mulch pulled back 2–3 inches from the trunk to prevent rot.
From experience, consistent deep watering can halt browning and encourage recovery within a single growing season if roots aren’t dead.
Pests: Bagworms, Spider Mites, and Leafminers
Small pests do big damage quickly. Bagworms create brown patches; spider mites leave stippled, dusty foliage; leafminers tunnel inside needles.
- Inspect for bags or webbing and remove by hand if the infestation is small.
- Use Bacillus thuringiensis (Bt) for caterpillars, horticultural oil or insecticidal soap for spider mites, and systemic insecticides in severe cases.
- Treat early morning or late evening to protect beneficial insects and avoid leaf burn in hot sun.
Quote: “I once opened a summer irrigation problem only to find dozens of bagworms — careful inspection saved my hedge that season.”
Fungal Diseases
Phomopsis and Kabatina tip blight can cause browning. These often enter through stressed foliage.
- Prune out affected tips back to healthy growth and dispose of debris — do not compost.
- Improve air circulation and avoid overhead watering at night.
- Fungicides help as a preventive in early spring; in summer focus on cultural controls unless disease is spreading rapidly.
Root Problems and Overwatering
Paradoxically, too much water or compacted soil can suffocate roots and cause browning.
- Check for soggy soil and poor drainage. If soil is waterlogged, cut back watering and consider improving drainage or building a raised bed.
- Aerate compacted soil around the root zone and topdress with compost to encourage root recovery.
Salt or Chemical Injury
Road salt, de-icing compounds, or herbicide drift can brown arborvitae suddenly.
- Flush the root zone with deep waterings to leach salts away; repeat several times after exposure.
- Avoid planting too close to roads or driveways in future and use salt alternatives in winter.
Practical Recovery Steps I Use
- Stop and diagnose — never assume the cause.
- Water deeply early in the morning, 1–2 times a week depending on heat and soil type.
- Remove completely dead branches now for appearance, but avoid heavy pruning of living tissue in summer.
- Treat pests promptly using the least toxic option that works for your infestation size.
- Improve soil with mulch and compost — healthy roots are the best defense.
- Be patient — arborvitae often recover slowly; expect improvement over months, not days.
When to Call a Professional
If most of the canopy is brown and scrape tests show dead tissue deep into the trunk, or if root rot and drainage problems are severe, get an arborist involved. A pro can assess root health, recommend targeted treatments, or advise replacement if necessary.
Preventing Browning Next Summer
- Install drip irrigation and timer to deliver consistent moisture.
- Mulch beds and keep a clear no-mulch ring at the trunk.
- Inspect monthly for pests, especially in hot, dry summers.
- Fertilize sparingly in spring only; avoid high-nitrogen late-summer feeds.
- Plant tolerant varieties or provide afternoon shade if summers are very hot where you live.
“A little attention now prevents a lot of heartbreak later — I’ve saved more hedges by checking soil moisture and removing a few pests than by any spray.” — Your Friendly Gardener
Final Thoughts
Saving a brown arborvitae in summer is often possible with quick diagnosis and steady care. Start with a moisture check, treat specific pest or disease problems, and commit to deep, regular watering and good mulch practices. Recovery may take a season or two, but with persistence you can revive most specimens and keep your landscape looking healthy year after year.
