Many varieties of cedar are found throughout Northern North America. Cedar cultivars have foliage that ranges from solid green to bronze to bluish-tinged needles. Yellow or brown needles, regardless of species, indicate the tree suffers from environmental stress.
The cedar tree's shallow root system makes it susceptible to root death. Excessive fertilisation, overwatering, underwatering and improper planting cause root problems that lead to foliage discolouration. When planting your cedar, be certain the twine and burlap from the bag are loosened so that the root ball can emerge.
In certain conditions, needle bronzing is normal. Some cedar species' foliage turns blue or gold in winter as a response to frigid temperatures. Road salt can cause foliage to brown so keep the tree's area clear of ice melt and other chemicals. Foliage browning in summer may be the result of water stress and herbicide exposure. Take care to water your tree so that the ground around it is moist through the top 18 inches. Avoid spraying herbicides near your cedar tree.
Horticulturists from North Dakota State University advise pruning out brown and yellow needles and branches, but only if these conditions are present in limited amounts throughout the tree. Yellow and brown needles covering the tree indicate the tree cannot be saved. Snip out the brown spots and ensure the soil is evenly moist but not sodden. Maintain regular irrigation and the tree should survive.
- United States Department of Agriculture: Western Red Cedar Plant Guide
- Ohio State University Horticulture and Crop Science: Arborvitae for the Home Landscape
- British Columbia, Canada Department of Agriculture: Dying Cedar Hedges -- What Is the Cause?
- North Dakota State University Extension: Questions on Cedar