Rhododendrons are among the most popular flowering shrub for gardens in most of the Northern Hemisphere, and parts of the Southern. With over 1,000 species in the genus Rhododendron, there really is something for everyone.  Their large, showy flowers and evergreen leaves have made them a favorite, sometimes called The King of Shrubs.

The genus Rhododendron, part of the family Ericaceae, is quite complicated. There are 8 or 9 sub-genera, which are further broken down into sections, sub-sections and series. To make it even more confusing, it has been reconfigured more than once, and there are proposed changes pending now. For our purposes, all we need to know is that Rhododendrons are perennials, mostly evergreen, mostly shrubs. They are grown mainly for their flowers, though some have ornamental leaves or attractive bark.

Rhododendrons can be grown in zones 3-9. Some types of Rhododendron can grow up to 25 feet tall and 25 feet wide, but that is probably not the kind you’ll find at your local nursery. Make sure that you get one that will grow to a size appropriate for your yard. They are easily damaged by wind, so the best spot to plant them is on the East or North side of a foundation or a wall. Good drainage is very important also. If the site does not drain well, you might want to build a raised bed. Rhododendrons also prefer a humid climate, acid soil with a pH of 5.0 to 5.5, and lots of organic material in the soil. Morning sun with afternoon shade is preferable. Too much sun can bleach out the flowers. Too much wind can cause leaf scorch or split the bark, which can be fatal.

I am much more careful today to make sure I have the appropriate site, the right sun/shade mix, and the correct soil. Years ago, when I planted 2 Rhododendrons in my back yard, I knew nothing about any of these requirements, and didn’t take the time to find out.  The placement is good, it is on the East side of a foundation, and it gets morning sun. But, my soil is not well drained, it’s too heavy, doesn’t have enough organic material and I suspect it is probably not the right pH. Knowing what I know now, it’s not hard to figure out why my Rhododendrons bloomed every year, but had very few flowers. I also found out the hard way that they have delicate roots, which cannot push through heavy or rocky soil. This spring, I accidentally brushed against one of my bushes, and it fell right over. In all these years, it had never grown roots outside the original ball! Needless to say, if I ever plant another Rhododendron, I would do things differently.

Rhododendrons can be found with a wide range of flower colors, from white to pink to red, along with purples, orange and yellow. Their 5 part flowers grow in clusters of bell shaped flowers, blooming in May & June. The flower clusters should be snapped off as soon as they are done blooming. I’m told that this will help the plant produce even more flowers next year.  The plants should be mulched heavily in the winter to protect the roots and conserve moisture. Leaves can be loosely piled around them, but air must be able to flow freely.

A few other interesting facts: Rhododendron is the state flower of both West Virginia and Washington. Some species can be invasive in woodland areas. Rhododendron is also poisonous, and can be fatal to grazing animals. The symptoms that result from humans eating them are not pleasant either. People have been known to get sick as a result of eating honey made by bees that gathered nectar from Rhododendrons.


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