What Causes Winter Scorch on a Rhododendron?

Winds

• Drying winds accelerate evaporation, which removes moisture from the leaves. When there is no snow cover on the ground and the ground is still frozen, the condition is more severe. The rhododendron roots cannot send moisture to the leaves to replenish moisture loss.

Sun

• As the sun angle gets stronger in late February and March, this is a very vulnerable time for rhododendrons. The stronger sun puts more pressure on the foliage as it increases the need for moisture.

Drought

• Rhododendrons have shallow roots and are sensitive to drought conditions. Drought, of course, reduces the moisture available to the leaves.

Fall Planting

• When new plantings take place in the fall, there is often not enough time for the roots to spread out in the soil and get established before the ground freezes. The rhododendron is dealing with transplant shock as winter sets in and the plant enters a semi-dormant state. This exacerbates the wind and sun issues that set in later in the season.

Recovery

• Fortunately, rhododendrons do recover from winter leaf scorch. If you do nothing, eventually the dead foliage drops off and new growth takes its place. Alternatively, you can prune the rhododendron and remove all the branches with dead foliage. Rhododendrons generate new growth from dormant buds that exist along the branches. This is a great opportunity to rejuvenate an old rhododendron. An application of a fertilizer for acid-loving evergreens gives the plant a boost to produce new foliage. Follow all package directions.

Prevention

• To prevent or minimize winter scorch, spray the leaves with an anti-desiccant spray in November and March when temperatures are above 40 degrees Fahrenheit. Do not plant rhododendrons in the fall. Give your rhododendrons a major watering late in the fall before the ground freezes -- at least 2 inches of water. Do not plant rhododendrons in exposed conditions. Plant them near shelter from trees or buildings. If that is not possible, place a burlap screen around them in fall to shade them from the sun and to break the wind.