Your Guide to Planting and Caring for Rhododendrons

Just what is a rhododendron? They are the beautiful evergreen shrubs found in many gardens. They have either broad or thinner thick leathery leaves with colorful spring flowers which attract hummingbirds. But there is more to them than that. , though the two names are often used interchangeably and in error. Confused? Join the club! Common usage refers to rhododendrons as the plant with broad leaves while azaleas have thinner, longer leaves.

There are hundreds of varieties available of these two marvelous plants and most are grown quite successfully in zones seven through nine. Most plants burst forth with color in early spring and the dark green leaves look great all summer. The care of rhododendrons and azaleas is the same. But one of the primary concerns is choosing a variety which is suitable for your yard. Your local nursery or agricultural extension service can give you specific guidance.

Plants should be purchased in the spring in either balled and burlapped form or container grown. Be careful when planting the balled and burlapped varieties as they are particularly susceptible to transplant shock. The container-grown plants are often root bound and have a mass of roots outside the soil ball. If this is the case, make four or five quarter-inch cuts with a sharp knife from the top to the bottom of the soil ball, spacing the cuts evenly. This increases the chances of the plant’s survival by promoting root growth outside the root ball and allowing for better water penetration and absorption. You will want to select sturdy and well-branched plants as a spindly-looking plant may be an indication of a poor root system or early plant disease. . Too small and they won’t survive the winter while too big will have adjustment issues.

Rhododendrons and azaleas both require an acidic soil with a pH of 4.0 to 6.0. You can make soil more acidic by adding liberal amounts of peat moss and decaying oak leaves. You can also add ferrous sulfate, copperas, iron chelate, or finely ground dusting sulfur. Planting in loose soil rich in organic matter with good drainage is perfect for these beauties. If you have a drainage issue, consider a raised bed to solve the problem. Rhododendrons enjoy partial shade. It will make the blooms last longer and reduce injuries from the winter cold. Don’t plant under elms, maples, or other shallow-rooted trees as they will be in competition for water and nutrients, and the rhododendrons and azaleas will lose.

Planting the shrubs requires a little extra planning and consideration. The hole should be two times wider than the root ball and the same depth. This will help the roots grow faster and let the plant establish itself with ease. Do not fertilize the plant now; wait until it is established. Too much of a good thing (fertilizer) can be a bad thing at this stage. Put three – five inches of mulch around the plant to help conserve moisture and prevent weeds. You will need to water the plants frequently. Rhododendrons need the equivalent of one inch of rain every eight – nine days. But don’t let them become waterlogged.

Fertilizing the plants after they are established should be done lightly in March, May, and July, using a slow release formula designed for acid loving shrubs. Too much fertilizer will cause sudden leaf drop or brown leaf tips. Pruning helps to maintain a beautiful, compact plant. Heavy pruning should be done immediately following the flowering season. Tall limbs should be cut down inside the body of the plant. To promote branching, pinch out tips of new growth following the flowering period but before July 4th. If you go beyond this date, it will limit your flower production next year. Be sure to remove any dead or damaged branches. If your plant becomes to large or oddly shaped, cut back the entire plant to 12-18 inches above ground level. Keep the plant moist after this and the plant should regenerate quickly.