Arborvitae run short of water more easily than many shrubs because their roots stay near the surface. A dry spell, or a summer when the watering slipped, often shows up as browning, especially on young trees. Whether the tree comes back depends on where the browning is: the green tips are what regrow, and the brown wood is not.
Signs Your Arborvitae Needs Water
Drought browning starts in the interior of the tree and works outward.1Nature Hills Nursery. Why Are My Arborvitae Turning Brown? Causes & Fixes A thirsty tree gives up its oldest inner foliage first to save water for the branch tips, so the inner canopy turns straw-colored before the outer growth shows any stress.2Nature Hills Nursery. Why Are My Arborvitae Turning Brown? Causes & Fixes The foliage feels dry and crispy rather than soft, and the whole tree can look thin.3Nature Hills Nursery. Why Are My Arborvitae Turning Brown? Causes & Fixes If nothing changes, the browning reaches the outer shell and the tips start drying, and whole sections can die back and leave gaps in a hedge.
Because the outside stays green for a while, the problem is easy to miss. Part the outer branches and look into the center. Run your hand over the foliage too: drought-stressed sprays feel dry and rough and may shed brown scales onto your palm, while healthy foliage is soft and slightly springy. Then step back and look at the whole hedge. If browning appears on many plants at once, especially after a dry stretch, a shared cause like water is more likely than a problem with a single plant.
Checking the soil confirms what the foliage suggests. Dig a few inches down near the trunk; dry, dusty soil there backs up the diagnosis.
Next, find out which parts of the tree are still alive. Bend a few branch tips: flexible, green tips are living tissue, while brittle ones that snap and crumble mean that branch is likely dead. Scratch a little bark on a twig with a fingernail. Green and moist underneath means alive; brown and dry means dead. A tree can have living and dead branches side by side, so test several in different places. Compare the sunny or windy side with the sheltered side as well, since exposed sides dry out first.
Thirst or Something Else
Arborvitae shed their oldest interior foliage every few years.4WascoNursery.com. Arborvitae Browning: 4 Causes and the Best Fixes So inner browning that drops off in autumn while the tips stay green is normal.5WascoNursery.com. Arborvitae Browning: 4 Causes and the Best Fixes Timing and soil help tell the two apart: drought browning tends to show up during dry spells, often reaches toward the tips, and the soil is dry when you check.
Newly planted trees are the likeliest to be thirsty. They don’t yet have a full root system to keep the foliage watered.6Eco Tree Company. What Should You Do When Your Arborvitae is Turning Brown? Even fast growers like Green Giant can establish slowly and take extra time to reach full drought tolerance.7Kansas State University. Growth of four conifer species during establishment and the effects of recurring short-term drought on growth and photosynthetic capacity In a tree planted in the last year or two, browning often means it is short of water, so check the soil first.
Thirst can also be mistaken for too much water. Soggy soil that stays wet for days points to overwatering or poor drainage. Overwatered roots rot, and the tree browns even though water is plentiful.
Winter can cause browning that is still a water problem. Winter wind dries the foliage while frozen soil keeps the roots from replacing what is lost.8Contributions from the Institute of Low Temperature Science. Mechanism of Desiccation Damage of Forest Trees in Winter The damage often appears in late winter or spring on the windward side, and a deep watering in fall before the ground freezes helps prevent it.
Drought-stressed arborvitae are more likely to be hit by spider mites.9Hortsense. Arborvitae: Spider mites To check, hold a sheet of white paper under a browning branch and tap the branch firmly. Tiny specks that crawl across the paper are mites; only bits of foliage and dust mean you probably don’t have them. Mite damage looks dusty or speckled rather than evenly straw-colored, and fine webbing between the foliage is another clue. Mites like hot, dry weather, so a tree can be thirsty and infested at once. If you find them, still fix the watering, because the water stress is what made the tree vulnerable.
Fungi follow drought as well. One fungus that attacks stressed woody plants causes branch dieback, sunken bark wounds, and browning.10Westside Eagle Observer. Brown arborvitae in Arkansas often linked to drought stress and botryosphaeria canker Tip blight fungus moves into tissue weakened by too little or too much water, freeze injury, or sunscald.11Pacific Northwest Pest Management Handbooks. Arborvitae (Thuja occidentalis)-Tip Blight
How to Water a Thirsty Arborvitae Back to Health
Water arborvitae deeply and infrequently rather than a little and often.12Epic Gardening. When and How Much to Water Arborvitae Shallow watering keeps roots shallow, and arborvitae roots are already shallow.13Epic Gardening. When and How Much to Water Arborvitae
- Hand hose: leave it on a slow trickle about a minute at a time, moving it around the root zone, until the soil is wet five inches down.14Plant Addicts. Watering Arborvitae
- Soaker hose: circle the roots and let it drip at least 15 to 30 minutes.15Plant Addicts. Watering Arborvitae In clay soil, place it out at the edge of the branches rather than against the trunk.16Plant Addicts. Watering Arborvitae
- Slow soak: soak each shrub slowly until water begins to puddle on the surface.17Glover Nursery. Arborvitae Planting and Care Guide
Bone-dry soil, especially packed soil or soil under thick dry mulch, can shed water so that it runs off instead of sinking in. Apply water in several short, slow rounds with pauses between them so the soil has time to start absorbing it. If the water beads up or runs away, keep going in short rounds. When it disappears into the ground, the soil is taking it in again.
For a hedge, each plant needs its own soaking, not one quick pass along the row. A soaker hose snaked along the row saves time. Plants at the ends or in full sun often dry faster, so give them extra attention.
Don’t follow a fixed calendar for repeat watering. A few days after a deep soak, push a finger in a few inches. Water again when the top few inches feel dry, and wait if they are still damp. In hot, windy weeks, check more often, because the soil dries faster.
Will the Brown Parts Turn Green Again
Arborvitae only grow new foliage from newer green wood.18Bower & Branch. How To Prune And Care Tips For Arborvitae Trees Branches that are brown all the way to the tips won’t sprout again. A branch with green at its tips can keep growing and slowly fill in.
The first sign of recovery is tips staying green and firm instead of drying out further after you correct the watering. New growth usually shows at the next growing season, so don’t expect quick change in the first weeks. Filling gaps can take more than one season, and only where living green growth remains. Dead inner foliage may drop off on its own over time, which looks messy but isn’t a new problem.
When pruning, cut out only fully dead, brittle branches. Cutting back into bare wood leaves a hole that won’t refill.19Bower & Branch. How To Prune And Care Tips For Arborvitae Trees
Some trees won’t make it. One that is brown to the tips on most branches is unlikely to recover, and a plant with large dead sections may never look full again in a hedge. Wait through one growing season before deciding, unless no green remains.
What Not to Do While It Recovers
Hold off on fertilizer for a struggling arborvitae, because fertilizers are salts.20Cooperative Extension: Garden and Yard. How can I bring my Arborvitae back to good health? Fertilizing a sick plant can stress it further and may even kill it.21Plant Addicts. Fertilizing Arborvitae22Plant Addicts. Fertilizing Arborvitae Wait until the tree shows steady new growth. Well-planted trees often need none at all,23Cooperative Extension: Garden and Yard. How can I bring my Arborvitae back to good health? and a soil test can show whether anything is actually lacking.
Panic watering is the other trap. Watering every day can swing a thirsty tree into soggy soil, and roots without air begin to rot. A deep soaking followed by a wait lets the soil dry partly between waterings, which suits the roots better than constant wetting. If browning continues while the soil stays wet, suspect overwatering and cut back instead of adding more.
Other stresses add up. Drought combined with compacted soil or de-icing salt sharply cuts the water a tree’s roots can take up.24Arboriculture & Urban Forestry. Which Tree Species Best Withstand Urban Stressors? Ask the Experts Keep salt and foot traffic away from the root zone of a recovering plant.
Keeping Arborvitae From Drying Out Again
A layer of mulch helps hold moisture in the soil, and loose soil with mulch helps water reach the root zone.25University of Missouri Extension. Underwatered Arborvitae: Signs and How to Save It Spread mulch out to the edge of the branches, a few inches deep, keeping it off the trunk.
Spots that dry out quickly deserve thought too. Soil near pavement, walls, or dryer vents loses water fast, windy exposed sites pull more water through the foliage, and tightly spaced hedge plants compete for the same supply.
Arborvitae in containers face both dry soil and overheated roots.26MDPI Agronomy. Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae Black pots heat roots far more than white ones, which cut peak root temperature by up to 7 °C.27MDPI Agronomy. Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae Adding compost to potting mix held more water and cut the watering needed by up to 40%.28MDPI Agronomy. Container Color and Compost Substrate Affect Root Zone Temperature and Growth of “Green Giant” Arborvitae Light-colored pots and a compost-rich mix are the better choice for container arborvitae.
A simple yearly rhythm keeps things on track. For the first one to two years after planting, water deeply about once a week unless there has been a good rain. Watch more closely during summer heat and dry spells, checking the soil rather than waiting for browning. Older, established trees usually need help mainly during long droughts.