Interior Browning in Mature Arborvitae Hedge: Normal Seasonal Shed

20-year-old, 20-foot Thuja occidentalis 'Pyramidalis' hedge in Seattle shows interior thinning/browning and yellowing tops.

Normal Evergreen Physiology

• Arborvitae hold needles 3–4 years
• Annual fall shed of oldest (interior) foliage
• Winter bronzing: yellow-brown but pliable, moist needles
• Spring green-up confirms health

When to Worry

• Browning extends to branch tips
• Needles dry, brittle, not pliable
• No spring green-up
• Cankers, resin flow, or insect evidence

Recommendation

Wait through spring. If new growth emerges green and tips recover, it's normal cycle. Seattle's climate favors arborvitae—this is likely seasonal.