Why Are My Boxwoods Dying?

Q. Can you tell me why my boxwood shrubs are showing signs of dying?

A. The usual reason for this kind of dieback in our climate is either a watering problem (keeping the soil too wet or not watering frequently enough which is drought) or wet mulch against the trunk of the plant.

Boxwoods dying back because soil is kept too wet, they were planted too deep or wet mulch is in contact with their stems.

Be sure you pull any mulch back away from the stems of the plants. Six or 8 inches is enough just so it does not touch the stem when it is wet.

Wet mulch can contribute to collar rot where the lower stem or trunk rots from too much moisture and the presence of disease organisms. The organisms are always there, they just need the right environment to develop. The right environment are wet conditions against the trunk and plant stress. Sometimes they don’t even need the stress.

Die back can also be because the soil is kept too wet. Roots need to dry out between irrigations. If they don’t, they will die back causing the stems to die back as well.

Keeping the soil too wet or too dry can look identical above ground. This is because root dieback or death is the same thing as drought. The roots die and can’t supply water to the top and the plant stems die back due to drought for different reasons; lack of water or too much in the soil causing roots to die.

Pull the mulch away and let it dry out before it gets too far along. It is most likely not a disease in the tops but in the stems or roots.