Garden Update: Browning Needles of Juniper and Arborvitae

By Kathleen Cue, Dodge County Extension Horticulture Educator (Week of May 16, 2022)

Many tree owners have been confronted with browning evergreens this spring. Even the tough-as-nails-never-needs-attention junipers are brown, in some cases entire trees. The winter of 2021-2022 showed deepening drought and this dryness, coupled with strong winds, was death to many evergreens, particularly junipers and arborvitaes.

Evergreens are unique for their ability to photosynthesize on days when temperatures are above 45 degrees F.  The region saw a lot of days like this with the mild winter. But the process of photosynthesis is hard work, requiring water along the way. When water cannot be replaced because of dry soils, then brown needles are the result.

What can tree owners do? First, trees may not be dead so giving them another week or two  before cutting them down will give them time to rally. For those trees that survived but are looking rough, practice good tree care. In the absence of precipitation, water 1 inch per week.  It’s best to apply the water all in one application. Be sure to water trees and shrubs in the fall, going in to ground freeze, to help them overwinter.

Refrain from using any lawn weed herbicide containing dicamba as this can spread to trees.

Do not fertilize trees as this deepens tree stress.

Mulch with 2-4 inches of wood chips or shredded bark. Never pile mulch against the trunk and refrain from using landscaping fabric beneath.

Trees that are well watered in the fall and mulched make it through the winter much more successfully than those that are not.