In both northern and southern climates, Rhododendrons are popular landscaping plants. Hardy and low maintenance, evergreen Rhododendrons flower reliably in summer and provide a hint of color throughout the winter months. When grown under favorable conditions, “rhodies” will perform well and resist common cold weather injuries such as leaf burn, bud kill or bark splits. With appropriate care, they will survive even the harshest winter.
Choose the right plant. Some rhododendrons are suitable for areas as far south as zone 8 and as far north as zone 3. Warm weather varieties may suffer cellular damage and death in a hard freeze. If planted too far south, cold weather varieties may break dormancy in a winter warm snap.
Amend the soil if necessary. Rhododendrons require excellent drainage and an acid soil pH. The healthier and stronger your Rhododendrons are, the better they weather the winter. To improve drainage, add compost and sand to the planting area. To lower soil pH, add cottonseed meal, composted leaves or peat moss.
Do not fertilize after June. Fertilizing in late summer or early fall can cause new growth that will be vulnerable to winter leaf burn or bud die off.
Water until the first hard frost. All shrubbery should be watered through the fall to prevent winter dehydration.
Apply 2 to 3 inches of mulch to protect Rhododendron’s shallow roots. Allow a 2 to 3 inch ring around the trunk of the plant. This will reduce rodent damage.
Block drying winter winds. If your Rhododendron is planted in a spot that receives direct winter winds, consider erecting a burlap wind barrier approximately 1 foot from your plants. Pound several 2 inch by 2 inch by 8 foot wood stakes into the ground to a depth of 1 foot. Staple burlap from top to bottom to create a screen.
Apply an anti-desiccant spray before the first hard frost and again in mid-winter. These sprays are also known as antitranspirants. They coat the leaves to prevent moisture loss and degrade over time. To prevent interfering the spring growth, do not apply after mid-February.
Build a snow shelter. If your Rhododendrons are subject to snow damage, protect them with wooden shrub teepees. These structures area available from nurseries and home centers and are placed over shrubs to deflect heavy snow accumulations.