Plant arborvitae in early spring or early fall with the top of the root ball 1–2 inches above the surrounding soil, in a wide hole filled with native soil, followed by deep watering and a 2–3 inch mulch layer kept away from the trunk.
The most common reason these evergreens turn brown and die isn’t disease or pests — it’s a burial error made on planting day. Whether you’re building a privacy screen or anchoring a corner bed, the rules are the same.
Choosing the Right Planting Site and Season
Arborvitae (Thuja) thrive in USDA Hardiness Zones 3 through 8, making them adaptable to most of the continental US. The single most important site requirement is drainage — roots sitting in soggy soil will rot within weeks. Pick a spot that gets at least 4 hours of direct sun for hedges and 6 hours for individual trees; afternoon shade helps in hotter climates like the lower Midwest and South. The soil pH can range from 6.0 to 8.0, so a standard garden soil test is rarely needed.
Plant in early spring (March–May) or early fall (September–October). Both windows give the roots time to establish before temperature extremes hit. Summer planting is risky unless you can commit to daily watering for the first two months.
How Wide and Deep Should the Hole Be?
This is the rule that keeps your tree alive. A hole that’s wide enough lets roots spread into loosened soil instead of circling. A hole that’s shallow enough ensures the top of the root ball sits 1–2 inches above the surrounding grade. That raised position lets oxygen reach the root crown and prevents the trunk from rotting.
Dig the hole the day before planting so the soil has time to air. Set aside the excavated dirt to use as backfill. Don’t add compost, peat moss, or any soil amendment to the hole — arborvitae establishes better when its roots grow into native soil from day one.
Step-by-Step Arborvitae Planting Process
Here is the sequence that professionals follow, verified against guidance from the University of Connecticut and Proven Winners nurseries. Work through each step in order and check the success cue at the end.
- Prepare the root ball. If your arborvitae came in a container, remove it and gently tease apart any roots circling the bottom. If it’s balled and burlapped, leave the burlap and wire intact until the plant is in the hole — cut them away from the trunk only after positioning.
- Rough up the root ball surface. Use your fingers or a hand cultivator to scratch the sides of the root ball. This breaks the smooth surface roots would otherwise circle on.
- Set the plant in the hole. The top of the root ball must sit 1–2 inches above the surrounding soil. Lay a shovel handle across the hole to check. If the root ball is too high or too low, lift it out and adjust the hole depth — never force it in.
- Backfill with native soil. Scoop the excavated soil back around the root ball. Tamp it down lightly with your hands to remove air pockets, but don’t stomp it compact. Let a garden hose run slowly into the hole as you backfill — the water settles soil around the roots naturally.
- Water until it puddles. After the hole is filled, water the entire root zone until a puddle forms on the surface, then stop. This saturates the root ball and the surrounding soil, eliminating large air gaps.
- Apply mulch — correctly. Spread 2–3 inches of shredded hardwood mulch or pine fines over the root zone. Keep the mulch 4–6 inches away from the trunk. A mulch volcano against the bark traps moisture and causes decay.
When you finish, the root ball sits visibly higher than the lawn or bed, and the trunk has bare soil around it with no mulch touching. Within one week, the foliage should look firm and upright — not drooping or yellowing.
| Planting Step | Common Mistake | What It Does to the Tree |
|---|---|---|
| Hole depth | Digging as deep as the root ball | Root ball sinks below grade; trunk rots |
| Backfill material | Using pure compost or potting mix | Roots stay in the hole instead of spreading |
| Mulch placement | Piling mulch against the trunk | Bark decays; insects and fungi move in |
| Spacing for hedges | Planting too close for mature width | Hedge stays thin at the bottom; plants compete |
| Watering schedule | Frequent shallow sprinkling | Roots grow shallow; tree dries out fast |
| Fertilizer timing | Adding high-nitrogen feed at planting | Burns tender new roots; delays establishment |
| Staking | Leaving stakes on past one year | Trunk grows weak; tree snaps in wind later |
The First-Year Watering Schedule
The watering schedule changes as the roots grow. Follow this timeline to avoid both under- and over-watering, which are the two leading causes of death in new arborvitae:
- First 2 weeks: Water every other day. Each time, soak the root zone until water puddles.
- Weeks 3 through 8: Water 2 times per week, deeply enough that moisture reaches 6–8 inches down.
- Rest of the first year: Keep the soil consistently moist. In the absence of rain, deliver roughly 1 inch of water per week until the ground freezes.
Use ground-level or drip irrigation rather than overhead sprinklers. Water splashing on lower branches can spread fungal spores that turn foliage brown.
When and How to Fertilize Arborvitae
Fertilizer can do more harm than good if applied too early. Wait the first two years before using a general-purpose feed.
Scatter it evenly under the drip line — the circle where the outermost branches end — and water it in. Skip fertilizing in late summer or fall; late-season growth is tender and gets killed by early frost.
Pruning and Long-Term Maintenance
Prune arborvitae in late winter or early spring, just before new growth starts. For hedges, trim the sides so the top is narrower than the bottom. This lets sunlight reach the lower branches and keeps the hedge full from ground level. Never cut into bare wood inside the green foliage line — arborvitae don’t regrow from old wood, and you’ll be left with a permanent gap.
If you’re preparing a hedge, choosing the right mulch for arborvitae matters just as much as the pruning method. The wrong mulch or a thick layer pressed against the trunk invites decay that no amount of pruning can fix.
Staking Large Arborvitae
If your arborvitae is 5 feet or taller at planting, stake it for one year. Drive two stakes into the undisturbed soil outside the root ball, use wide flexible straps, and remove everything after 12 months. Stakes left longer become a crutch — the trunk doesn’t develop the strength to stand alone, and the tree may snap in a heavy wind later.
Deer and Heat Protection
Deer browse arborvitae foliage, especially in winter when other food is scarce. If deer are active in your area, surround new plantings with fencing or a physical barrier for the first two years. Also avoid setting bare-root plants on blacktop, concrete, or asphalt before planting — those surfaces radiate heat that dries out roots fast. If you must delay planting, keep the root ball shaded and water it daily.
| First-Year Task | How Often | Why It Matters |
|---|---|---|
| Deep watering (first 2 weeks) | Every other day | Settles soil; eliminates air pockets |
| Deep watering (weeks 3–8) | Twice per week | Trains roots to grow deep |
| Mulch inspection | Monthly | Keep 4–6 inches from trunk |
| Stake check | Every 3 months | Loosen or remove after 12 months |
| Winter watering (warm spells) | As needed above freezing | Prevents winter desiccation |
Final Planting Checklist
Before you finish, confirm each item: hole is twice as wide and one inch shallower than the root ball; root ball sits 1–2 inches above grade; backfill is native soil only; water soaked until it puddled; mulch is 2–3 inches deep and pulled back from the trunk; watering schedule is set for the first two weeks. Arborvitae planted this way establish fast and hide their planting depth gap within a single growing season.
FAQs
Can I plant arborvitae in clay soil?
Yes, but only if you improve drainage first. Clay holds water and suffocates the roots. Dig the hole even wider — three times the root ball width — and mix in coarse sand or pine fines. Better yet, plant on a slight slope or a raised mound so water runs away from the root zone.
How far apart should I space arborvitae for a privacy hedge?
Space them at least two-thirds of the plant’s minimum mature width apart. For a variety that spreads 12 feet wide at maturity, set each plant 8 feet apart. Closer spacing may look full at first, but the lower branches will die back from overcrowding within a few years, leaving a hedge that’s bare at the bottom.
Should I stake a small arborvitae?
Only trees over 5 feet tall need staking, and only for one year. A shorter tree develops a stronger trunk when it’s allowed to sway in the breeze. Staking a small arborvitae stalls that natural strengthening process and leads to a weaker plant long-term.
Why are my newly planted arborvitae turning brown?
Brown foliage in the first two weeks usually points to one of three issues: the root ball was planted too deep, the soil is staying soggy, or the tree isn’t getting enough water. Lift the mulch and check the soil moisture at root depth. If it’s wet and the root ball sits below grade, replant higher immediately.
Can I plant arborvitae near a fence or house foundation?
Yes, but leave enough room for the mature width. A good rule is to plant one full mature tree width away from any structure. If the variety spreads 10 feet wide, set the center of the hole 10 feet from the fence or foundation. This keeps branches from rubbing against walls and allows air circulation that prevents disease.
References & Sources
- Proven Winners. “How to Plant Arborvitae.” Covers root ball preparation, watering schedule, and sunlight requirements.
- University of Connecticut. “Arborvitae Factsheet.” Provides fertilizer recommendations, spacing, and hardiness zone data.
- New York Botanical Garden. “Arborvitae: Plant Care Guide.” Details proper planting depth, staking duration, and irrigation methods.