Keep ‘Em on the Up and Up Protecting Upright Evergreens from Snow-load Breakage.

By Curtis Utley, CSU Extension Agent, Jefferson County

Upright junipers. The center specimen has a co-dominant leader

Upright or fastigate evergreens are a common and attractive feature of many home landscapes often used as screen plantings or focal points in narrow planting beds. However, In Colorado, or any community frankly that experiences heavy snow fall in the winter, these narrow specimens can be damaged, disfigured or down-right destroyed by heavy snows.  Why does this occur?

Snow-load impacted Arborvitaes

Narrow tree forms succumb to snow load breakage because the side branches are poorly attached. The strongest branch attachment forms a 90 degree angle between branch and trunk (think of any native spruce or fir). When branches are attached more acutely there is

Right-angle branching

less trunk material to hold the branch into its socket. The likelihood of included bark forming between the trunk and a branch increases if a branch immediately ascends from the tree’s trunk. The other reason Fastigate cultivars often break in snow load events is our fault in how the trees are pruned and managed. Most narrow cultivars are sheared to keep their appearance balanced and tidy. If the terminal branchlette is clipped and apical dominance is removed, aggressive, competing side branches will try to grow up and become the leader.

Strong central leader

If these competing side branches are maintained they will grow into co-dominate leaders that will have included bark in the future and may break in future snowstorms.

Co-dominant leaders failing after heavy snow load

So what should you do to protect your fastigate trees in the winter?

Wrap them with Ag fleece.

Ag Fleece protects shrubs from snow-load and desiccation

1. Wrap them with straps

Wide strap wrapped around a Woodward juniper

Light cord or Christmas lights can prevent snow load breakage 

2. Wrap them with Christmas lights or light cord

3. Stake them when small and tie them loosely to the stakes