Arborvitae 'Emerald Green' Black Patches: Transplant Shock

Black patches on the lower foliage of newly planted (6 weeks) 'Emerald Green' arborvitae are almost certainly transplant shock, not disease. The lower, inner foliage is shaded and naturally sheds as the plant adjusts.

What's Normal

• Inner/bottom foliage browns and drops—this is self-thinning.
• Outer/top foliage stays green and healthy.
• New growth at tips = good sign.

Care for Establishment

1. Water deeply 1 inch/week (use pan method). Soak root ball and surrounding soil.
2. Mulch 2–3 inches in 3-ft ring (keep off trunk).
3. No fertilizer first year.
4. Check drainage—arborvitae hate wet feet. Soil should drain within a few hours.

When to Worry

• Browning spreads to outer/upper foliage.
• Tips turn brown.
• No new growth by late spring.
• Foul odor, mushy roots = root rot (Phytophthora).

Your trees are likely fine. Consistent moisture and patience will get them established.