Arborvitae (Thuja) Care Guide: Everything You Need for a Healthy Privacy Hedge
Arborvitae (Thuja spp.) are the backbone of many Northeast Ohio landscapes. They are fast-growing, evergreen, and provide year-round privacy. However, a “set it and forget it” approach often leads to brown, sparse, or dying trees. To maintain a lush, dense screen in the Cleveland area, you need to master the basics of spacing, deep watering, and seasonal protection.
Choosing the Right Arborvitae Variety
Success starts with picking the right tree for your specific spot. In Northeast Ohio, four varieties dominate the landscape:
- ‘Emerald Green’ (Thuja occidentalis): Reaches 10–15 feet tall and 3–4 feet wide. Its narrow, columnar habit makes it perfect for tight property lines.
- ‘Green Giant’ (Thuja standishii x plicata): The speed demon of the family, growing up to 3 feet per year. It can reach 40–50 feet tall and 12–15 feet wide. Best for large properties needing massive screens and is significantly more deer-resistant.
- Techny: A very cold-hardy variety that maintains a deep green color even in harsh winters. Grows about 15 feet tall and wide.
- American Pillar: A newer variety that is even narrower than Emerald Green but grows faster, reaching 20+ feet tall while staying only 4 feet wide.
Planting for Long-Term Health
Most arborvitae failures happen in the first 12 months due to poor planting technique.
1. Spacing is Critical
Overcrowding is the #1 cause of disease and thin growth.
- Emerald Green: Space 3-4 feet apart from trunk-to-trunk for a dense hedge.
- Green Giant: Space at least 5–8 feet apart. They need massive airflow to prevent needle blight as they mature.
2. Soil and Sun
Arborvitae need at least 6 hours of full sun. While they tolerate partial shade, they will become sparse and “leggy” without enough light. They prefer well-drained soil; they “hate wet feet.” If your yard has heavy Cleveland clay, plant them slightly high (root ball 1-2 inches above ground level) and mulch heavily (2-3 inches, keeping mulch away from the trunk).
The Secret to Success: Deep Watering
Arborvitae have relatively shallow root systems. If they dry out once, the damage is often permanent.
- First Season: Water deeply 2–3 times a week. Use a soaker hose for 1-2 hours per session to ensure water reaches the bottom of the root ball.
- Established Trees: They still need deep watering during Ohio’s July and August dry spells. If the needles feel brittle or look dull, they are thirsty.
- Fall Watering: This is the most forgotten step. Deep water your trees right up until the ground freezes. Hydrated needles are much less likely to suffer from winter burn.
Trimming and Maintenance
Arborvitae don’t require pruning, but a light annual trim keeps them dense.
- When to Prune: Early spring (March/April) or early summer (June). Avoid pruning in late fall.
- The Golden Rule: Never cut back into the “dead zone”—the brown interior where there are no green needles. Arborvitae will not regrow from old wood.
- Professional Maintenance: For tall hedges (over 10 feet), hire a pro. Trimming the tops (“topping”) is necessary to keep them from splaying open under heavy snow, but it requires precision to avoid ruining the tree’s natural shape.
Winter Protection in Northeast Ohio
Lake-effect snow and dry winter winds are the biggest threats.
- Burlap Wrapping: Wrap narrow varieties like Emerald Green in burlap or use heavy-duty garden twine to spiral-wrap the branches. This prevents heavy snow from bending and snapping the central leaders.
- Anti-Desiccants: Spraying a waxy coating (like Wilt-Pruf) in late November helps prevent the needles from drying out in the wind.
Common Problems & Solutions
- Bagworms: These look like small pinecones made of needles. They can strip a tree in days. Pick them off by hand in winter or spray with Bt in early June.
- Deer Damage: Deer love arborvitae (especially Emerald Green). If you have high deer pressure, use repellents or choose ‘Green Giant.’
- Browning: Can be caused by spider mites, drought, or winter burn. Shake a branch over white paper—if tiny specks crawl, it’s mites.
Frequently Asked Questions (FAQ)
How fast do arborvitae grow?
Emerald Greens grow about 6–12 inches per year. Green Giants can grow 3 feet per year once established.
Why is my arborvitae turning brown in the middle?
It’s likely “seasonal needle drop.” Older, interior needles turn brown and fall off every autumn. This is normal. If the tips are brown, you have a watering or pest problem.
Can I save a brown arborvitae?
If the branch is brittle and snaps, it’s dead. If it’s still flexible, deep watering and patience might bring it back, but it takes years to fill in holes.
Do I need to fertilize?
Apply a slow-release evergreen fertilizer (like Holly-tone) in early April. Stop all fertilizing by July 1st to avoid tender new growth that will freeze in winter.