A Spring Color Explosion


Every spring, rhododendrons steal the scene with their show of flowers. Most alluring are those in nuanced shades of violet and blue, but there are also varieties that bloom yellow, white, pink, orange, and red. Rhododendron shrubs can be found in almost every corner of the earth; worldwide, there are more than 1,000 species and varieties in a broad spectrum of sizes, from dwarf exemplars that grow just 8 inches high and are excellent for use in small or curbside gardens, to the 'giants' that top at 16 feet.

Azaleas, by the way, also belong to the botanical genus Rhododendron. Landscape designers like to use rhododendrons for a number of reasons, not just for their magnificent blossoms: these evergreen plants bring structure and year-round color to the garden. Their thick, dark green leaves are a defining characteristic, and some varieties sprout silver-white and develop a soft pelt of brown on the underside of the leaves.  After blooming, rhododendrons will tolerate being cut back. So-called tree rhododendrons are progressively pruned of lower branches, or ‘arborized.’ The results can be truly monumental, and the plant will be compelling even after it’s stopped flowering.

Planting and Care

Rhododendrons are generally long-lived plants that do best, however, in spots that meet specific conditions. They thrive in acidic soil where drainage is good, without standing water. Since woodland is the natural habitat of rhododendrons, they will also prefer partial shade in the garden. To achieve healthy growth, a location with loose, acidic soil is key: the optimal soil pH for growing rhododendrons is between 4.2 and 5.5. There are, however, some lime-tolerant varieties that will grow in clay or loam soils up to 6.5 pH, which is more typical of garden soils. The root structure of a rhododendron is very delicate, and it’s important to give it enough depth when planting. To provide the most favorable conditions for a newly planted rhododendron, it’s best to fill the planting hole with a mix of peat and specialized rhododendron soil. Top the soil with bark mulch every year, and supplement with rhododendron fertilizer. Compost is not suitable for fertilizing rhododendrons because of its high pH value. To get the most from the blooming period, remove spent blossoms regularly; this will prevent the shrub from expending energy forming seeds and encourage it to put out new buds instead.

Next week, learn more about planning a rhododendron garden. (BGL)

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