Wednesday, May 16, 2012

Rhododendrons

Rhododendrons are marvelous shrubs to have on a property because they are dramatic, showy plants that add texture.  Their round clusters of flowers really enhance the landscape with a bit of flair and a lot of color beginning in early May; bloom times will vary depending on the type of rhododendron.  Ranging in size from a compact 3 feet (such as Rhododendron degronianum) to a gigantic 18 feet (Rhododendron maximum), any one of the Rhododendron cultivars can be planted in a zone appropriate area, if one does some planning and takes certain things into consideration.  As for color, there is a wide spectrum from which to choose.  From pale creams & whites, to shades of pink, mauve, magenta and even purples can be had for the home.   

Most rhododendrons do well in light to partial shade and many prefer a northeastern exposure.  During the summer months, these shrubs should have shade during the afternoon when the sun is at its strongest.  Considerations for winter include protection from morning sun and blustery, cold wind.  Depending on the type of rhododendron (some are evergreen and some are deciduous), location and soil are key.  Rhododendrons are small when bought from a nursery, but they will grow an average of 4 to 6 inches annually.  Their growth pattern is both horizontal and vertical, so remember to give them plenty of space in which to grow.  The optimum soil for most of these shrubs should have a pH between 4.5-5.5 and should be well-draining.  Under no circumstances should rhododendrons be planted at the base of trees with shallow root systems, such as beeches, where they will compete for vital nutrients.  The root systems of these plants are shallow and quite fibrous, so it is highly recommended to mulch at the base of the plants and never to cultivate the surrounding soil.  Rhododendrons are best planted in very early spring before any growth occurs or in late summer after growth has ceased; planting, however, should be done before any cold weather commences.  

With this in mind, rhododendrons can still be planted even where optimal conditions don't exist.  Where soil does not drain well, consider planting on raised beds.  I've read that in England this is done with excellent results for gardens throughout the country.  At Brodick Castle Garden, in Scotland, on the Isle of Arran, the internationally acclaimed collection of rhododendrons are in full splendor during the spring.  If you happen to live there or are planning a trip in the future, it comes highly recommended.     

Around where I live, many properties have beautiful rhododendrons planted in various ways.  I love seeing them grouped together in one big mass along the border of homes, because they act as screens.  Let's take a closer look at Rhododendrons. 

At the edge of this property, where there is optimal partial shade, a wall of rhododendrons affords privacy and gorgeous beauty during the spring.

The throats of these clusters are a creamy white, yet the edges of the trumpets take on a pale pink shade that is utterly stunning.

A young rhododendron with lilac-colored clusters certainly brings a good amount of color to this yard.

A breathtaking, mature rhododendron is in full display.  As you can see, the lilac-colored flowers burst like pom poms all around the shrub.  This one has been nicely shaped.

At the edge of this property, which sits on a corner lot, the owners have managed to group several rhododendrons.  Notice that the house is completely sheltered from view.   

Do you know that the genus Rhododendron encompasses both rhododendron & azalea species in the botanical sense?  Azalea flowers usually have around 5 stamens, whereas rhododendron flowers have at least 10 or more.  This closeup photo clearly shows that.  Don't you just love this shade?   

A view from below to above (di sotto in su ), this beautiful rhododendron has no equal.


A closeup of the capsule shows the sepals just beginning to open up.  The dark red petals are emerging from this mid-May bloomer (considered early to mid season), which is planted near the eastern side of a colonial home.

This capsule is a bit further along in its blooming process.

As the sepals open up, the closed buds shoot upward and outward. 
Some flowers will open up before others. 

As soon as every flower has opened up, their unparalleled beauty is a sight to behold.  This is a very bold shade of pink.




Species rhododendrons are the most common available to the home gardener.  Their bloom time can range from early May through early July.  If you happen to live anywhere in zones 4-8, a series of them can be planted in order to enjoy successive bloom times.  Ironclad hybrid rhododendrons do well in zones 4-7 and are capable of withstanding harsh winter temperatures and windy conditions.  Dexter hybrids are a specialized group originating in Cape Cod that do well on the east coast in zones 6-8.  There are also Leach hybrids, Yakushimanum hybrids, small leaf rhododendrons and even those suitable for the mild climates of the Pacific Northwest.  Visit a nursery near you and inquire about these beautiful shrubs.  If you have the space and live in an appropriate zone for these plants, consider having one or two or more them.  Their blooms are certainly among my favorites. 

2 comments:

  1. Hi! Thank you for your post about Rhododendrons. I had a question I was hoping you could answer. There is a creek running behind my house in the backyard near the road and I'm looking for a good hardy shrub to plant that will do well in the shade. We have huge hickory trees back there and I wasnt sure if the rhododendron plant would be a good one? And if so, how far apart should I plant them and when is the best time ? I know your post said early spring but is there a more specific date? I'm pretty new at gardening! Thank you so much,I hope to hear back from you.

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  2. Veronica,

    Rhododendrons do well in partial shade. I have several scattered throughout our home. Some are located deep within the woods near the creek behind us, and they do thrive. Keep in mind that if there is a lot of standing water near that creek, the area will not be best for them. They don't tolerate stagnant moisture.

    Some things to consider: If you're going to plant rhododendrons, it really depends on where you live and what type you're getting.

    1. In order to get the best effect of these shrubs, it's best to group them together because if you give them too much space in between plantings you will have gaps. Depending on the type you choose (check with your nursery or catalog to see what their estimated growth & pattern will be), keep the larger ones behind the smaller varieties and always plant the shrubs with the root ball not any lower than ground level or you may kill the plant. --make sure your soil is acidic if it's too alkaline (check with your local extension for soil testing).

    2. Planting time will, again, depend on where you live. If you're here in the Northeast or in the midwest where it is cold now, then yes, early spring is best. If you live in a place where it is hot, your best planting time will be in the fall.

    3. Spring 2015 officially begins on March 20th. So, think around Easter time or so.

    I hope this helps!

    ~David

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