The Complete Guide to Rhododendron Shrubs
Evergreen rhododendrons are among the most popular flowering shrubs. They add bursts of color as specimen plants in any garden. Rhododendron blooms, which are larger than azalea blooms, usually open in May, and our plants bloom the first year. Depending on the variety, rhododendrons are hardy in zones 3-8 and do fine in shade.
Many gardeners choose a rhododendron based on color, size, bloom size and time. For example, placing red rhododendrons close to your home offers contrast to light, neutral house colors and greens up your landscape all year long. The blooms of a white rhododendron near your patio glow from the flames of your fire pit or solar lights in the evening. You also might choose a rhododendron variety based on its easy maintenance.
The Top Rhododendron Varieties
Lavender Rhododendron- To make a statement in the garden. This large grower can reach eight feet high and produce large, gorgeous lavender blooms.
Red Rhododendron- A popular choice with beginners because they require little maintenance or water, but still reward gardeners with showy red blooms.
Yellow Rhododendron- A compact and versatile choice to brighten any landscape. A unique color in landsacping.
White Rhododendron- To add contrast to night gardens and year-round evergreen foliage to the landscape.
How To Plant Rhododendrons
The first step toward success with rhododendrons is choosing a hardy plant. Well-established nursery stock, like the ones carried by Brighter Blooms Nursery, is toughened up and more likely to transplant well.
The next step to ensuring that rhododendrons thrive is to start them out with the right soil. They thrive in soils that are light and drain well. Before planting, make sure the soil is rich with acidic organic matter. Composted oak leaves and pine needles or pine bark usually work well. If you can prepare the soil in fall, that's even better. Your soil has more time to amend before spring planting of your rhododendron.
When placing a new rhododendron in the ground, take care with the shrub's fine roots, carefully loosening them up. It helps to plant as much of the container's soil mix as possible with the new rhododendron.
By placing a shovel handle or other long, level tool horizontally across the planting hole at ground level, you can line up the root ball along the ground level. If you have clay soil, be sure to plant your rhododendrons high, with about an inch of the root ball above the surface. While filling the hole with dirt, spread the roots out gently and cover the crown with soil. Rhododendrons need a good soaking immediately after planting. Mounding about two inches of mulch to encourage water to drain to the roots rather than away from them will help keep rhododendrons watered nicely.
Caring for Rhododendrons
Because rhododendrons have fine roots that grow slowly, they need more water in the first season. Depending on rain, they might need a weekly deep watering in addition to regular irrigation. If the plants wilt, the cause might be too much water, lack of water or temporary droop from afternoon heat. The best way to tell if a rhododendron needs watering is to probe the soil with a screwdriver or other object about four to five inches down. If the soil is moist, you don't need to water.
To make sure rhododendrons receive plenty of natural water, try to place them away from roof overhangs or far under a tree canopy. Mark off where the shrub will receive partial or full shade in summer, but still receive plenty of natural moisture.
Rhododendrons generally need little trimming or pruning. The best time to prune rhododendrons is right after blooming is complete. Deadheading, or snapping off, spent blooms makes rhododendron blooms flourish and helps prevent the chance of fungal disease.
Rhododendrons need little help from fertilizers, but mulches can break down and cause problems with nitrogen. You'll notice slowed growth and yellowing leaves. An ammonium sulfate fertilizer can help balance the nitrogen. If your rhododendron's soil is less fertile than desired, you can apply a fertilizer specifically designed for acid-loving plants in late winter or early spring. Be sure to follow the package directions for rhododendron application.
Facts About Rhododendrons
The name "Rhododendron" means "rose tree," which refers to the rose-like colors of many of the plant's species. Rhododendrons are native in many moist, deep woods in mountainous areas, especially of Maine, New York, Ohio and Georgia. And although rhododendrons delight southern southern gardeners and were chosen as the state flower of West Virginia in 1903, the Coast Rhododendron is the Washington state flower.
Sometimes, the terms "azalea" and "rhododendron" are used interchangeably. Azlaeas also are members of the genus Rhododendron, but the shrubs differ. Both have flowers with 10 stamens, the tiny, thin part in the middle of the flower than protrudes and produces pollen. And both are members of the Heath family. Aside from the larger blooms and leaves of the rhododendron, most rhododendrons are evergreen. Azaleas lose their leaves in winter.