Diagnosing Sudden Yellowing in a Row of Newly Planted Arborvitae

All 8 of my 'American' arborvitae, planted a year ago, are turning yellow simultaneously. Needles fall off when touched. Some green remains with berries. The landscaper says it's normal shedding. Is that true? I can send photos.

Not Normal Shedding

Arborvitae naturally shed inner, older needles in fall—but not all at once, not on every plant simultaneously, and not with the widespread yellowing you describe. This pattern points to an environmental stressor affecting the entire planting.

Top Suspects

1. Water Issues (Most Likely)

• Too wet: Poor drainage or overwatering → root rot (Phytophthora)
• Too dry: Inadequate establishment watering → desiccation
• Check soil moisture 6–8 inches deep—should be moist, not soggy or bone-dry

2. Planting Problems

• Burlap/twine not removed: Synthetic burlap or uncut wire baskets girdle roots
• Planted too deep: Root flare should be visible at soil surface
• Soil compaction: Prevents root expansion into native soil

3. Site/Weather Stress

• Extreme heat, wind, or reflected heat from hardscape
• Herbicide drift from lawn treatments
• Salt damage (if near roads/sidewalks)

Immediate Steps

1. Check root flare—gently excavate base to ensure it's exposed
2. Test drainage: Dig 12″ hole, fill with water. Should drain in <2 hours.
3. Adjust watering: Deep, infrequent soakings (1″/week) rather than frequent light watering
4. Mulch properly: 2–3″ wood chips, 3″ away from trunks

When to Worry

If >50% of foliage browns, or if bark at base is dark/soft (crown rot), the tree may not recover. An arborist can assess root health with a root collar excavation.

Photos would help, but start with the checks above. Uniform symptoms across a block planting almost always indicate a shared cultural or site issue.