Healthy arborvitae depend on planting in moist well-drained soil with full sun, watering deeply especially the first season, and pruning only in mid-spring without cutting into old wood.
Arborvitae may be one of the most planted landscape evergreens in the country, but the same qualities that make them a go-to hedge also make them easy to damage with a few common mistakes. Root rot from wet soil, permanent brown patches from shearing into bare stems, and failure from planting too deep are the three problems that kill more arborvitae every year than any pest or storm. The fix is simple if you know what to look for and how each season changes what the tree needs.
The Fundamentals Of Arborvitae Care
Arborvitae (Thuja) is a coniferous evergreen that grows on new wood each season. That one biological fact decides almost everything about how you handle it. The tree cannot sprout new growth from old brown stems — cut past the green and that spot stays bare forever. This makes pruning, watering, and placement non-negotiable from day one.
Sunlight, Soil, And Spacing: What To Get Right Before You Dig
Pick a spot with at least six hours of direct sun per day. Arborvitae tolerate partial shade but turn patchy and thin if they don’t get enough light. Soil should be loam or sandy loam that drains well — standing water around the roots guarantees root rot within weeks. The soil pH can range from 6.0 to 8.0, so you probably don’t need to adjust it unless a test shows something extreme.
Going tighter may look full faster, but the roots compete and the mature trees crowd each other into long-term weakness.
The Correct Way To Plant An Arborvitae
Proven Winners and extension services agree on this sequence. Loosen the surrounding soil for better drainage before you dig. Make the hole two to three times wider than the root ball but no deeper. Tease any circling roots loose if the plant is potbound. Set the tree so the top of the root ball sits at or slightly above ground level. Backfill with the original soil, tamp it lightly to remove air pockets, and water thoroughly.
Staking is rarely needed and can weaken the trunk’s natural strength. Only stake if the root ball is loose in the ground or the site is extremely windy.
Watering Schedule That Matches The Tree’s Age
Newly planted arborvitae need consistent moisture during the first six weeks. After that, established trees tolerate longer dry spells but still benefit from deep weekly watering during hot weather.
Use this schedule from Bower & Branch for the first season:
| Time Since Planting | Watering Routine | Duration |
|---|---|---|
| First 2 weeks | Slow drip every day | 2 to 4 hours |
| Weeks 3 to 4 | Slow drip every other day | 2 hours |
| Weeks 5 to 6 | Slow drip every 3 days | 2 hours |
| Established (6+ weeks) | Slow drip once a week | 2 hours |
| During dry spells | Deep soak every 1–2 days | Until soil is saturated |
Always water at the base of the tree. Overhead watering in direct sun scorches the foliage and encourages fungal disease. After the tree is established, a deep soak once a week during summer is usually enough unless you are in a drought region.
Fertilizer: Less Is More The First Year
Do not fertilize a newly planted arborvitae. The root system needs time to settle first. After the first year, use a root stimulator (Fertilome Root Stimulator is a common choice). In the second year, switch to an acid-loving plant food. Starting in the third year, a slow-release granular fertilizer like a 10-4-4 blend applied once in early spring gives the tree the nitrogen it needs for dense foliage without pushing soft growth that winter will kill.
If you prefer an all-purpose option, pick one with an acidifier like sulfur or gypsum to keep the pH slightly acidic.
Mulch Rules That Protect The Trunk
Piling mulch against the bark — called volcano mulching — traps moisture against the wood and causes rot at the root flare. A reader ready to lay mulch should look at tested options that balance moisture retention and air flow; the best mulches for arborvitae lists top performers sorted by climate and tree age.
Pruning: The One Rule That Saves The Shape
Never cut into brown wood without green growth on it. Arborvitae grow only from the tips and from green stems, not from the bare center. One snip into old wood leaves a gap that never fills in. No amount of waiting or extra fertilizer will bring that branch back.
That shows you exactly where the tree is going to grow and lets you shape it while the season is still early. If you want a formal hedge, give it a second light trim in mid-fall.
Seasonal Care Calendar: What Each Quarter Demands
The arborvitae’s needs shift with the calendar, and a lazy summer or a dry fall can undo a good spring start.
| Season | Key Tasks | Watch For |
|---|---|---|
| Spring | Inspect winter damage; prune lightly; fertilize early; refresh mulch; water if spring is dry | Winterburn, broken branches, deer rub |
| Summer | Water deeply 1–2 times per week; check mulch depth; hand-pick bagworms | Spider mites, bagworms, scorched tips |
| Fall | Light shaping prune; stop fertilizing; deep water before ground freezes; wrap young trees in burlap if site is windy | Dry soil going into winter, wind desiccation |
| Winter | Brush heavy snow off branches gently; no watering or pruning if frozen | Road salt exposure, ice damage, windburn |
In cold or windy areas, an anti-transpirant spray like Wilt-Pruf applied before winter reduces water loss through the needles and prevents the browning that people often mistake for a disease.
Final Checklist For A Healthy Arborvitae
- Six or more hours of sun per day
- Well-drained loam soil with pH between 6.0 and 8.0
- Root flare 1–2 inches above ground level
- Deep slow watering — frequent for the first six weeks, weekly after that
- 2–4 inches of shredded bark mulch, kept 2 inches from the trunk
- Prune only in mid-spring, never into bare old wood
- Fertilize starting the second year with a slow-release low-nitrogen blend
- Protect young trees from deer, road salt, and winter wind
Follow that list and the only thing you will need to handle later is the occasional bagworm removal in late summer and a light shaping prune each spring. Arborvitae are long-lived when the basics are right.
FAQs
Why is my arborvitae turning brown in the middle?
Interior browning is normal. The dense outer foliage shades the interior branches, and they drop needles naturally. If the browning spreads outward or appears only on one side, check for windburn, lack of water, or spider mites. Brown foliage that was pruned into old wood will not regrow.
Should I wrap my arborvitae for winter?
Young or thin-bark varieties benefit from burlap wrapping in areas with harsh winter wind and sun. The wrap prevents desiccation when the ground is frozen and the roots cannot take up water. Remove the wrap in early spring once temperatures stay above freezing.
How often should I water a mature arborvitae in summer?
Shallow sprinkling encourages weak surface roots.
Can I prune an arborvitae to keep it short?
You can prune the top once the tree is at your preferred height, but the tree will continue trying to send up new leaders. Head back the central stem to a lateral branch each year after it reaches the desired height. Never cut into the thick central trunk without green growth.
References & Sources
- Bower & Branch. “How to Prune and Care Tips for Arborvitae Trees.” Covers pruning timing, watering schedule, and planting steps.
- Green Giant Trees. “Arborvitae Care Calendar: What to Do Each Season.” Seasonal care breakdown for spring, summer, fall, and winter.
- Proven Winners. “How to Plant Arborvitae.” Official step-by-step planting instructions.
- Glover Nursery. “The Beginners Guide to Arborvitae Fall Care.” Covers mulch depth, fertilizer types, and watering for new trees.