Rhododendron

April 8, 2017

This year I do think I need to prune my rhododendrons.  I originally had three of them in my front yard and read instructions on how to prune, so several years ago I did this to one of them and it promptly died.  This year the biggest (about eight feet) needs to be pruned back.  The top branches look dead to me but I am afraid to touch it after what happened to its sister.  I had a chance to read your article recently on pruning but saw nothing on the rhododendrons.  I love these plants.  Not many people are able to grow them here but mine have just been beautiful.  People stop every year to find out what they are as they are not a 'familiar' plant.  My daughter in Oregon grows them, and they really thrive there.  If you can just give me some advice as to when and where to prune, I might have the courage to do it.

Rhododendrons do not normally thrive in Arkansas like they do in Oregon, but there are gardeners who have success.  The time to prune them is immediately following bloom. I would not prune off more than 1/3 of the branches. Selectively prune out a few branches back to the branch collar.  Take off the minimum amount of growth that you need to.  Lightly fertilize with an azalea fertilizer after pruning and pay attention to watering needs. 

February 4, 2017

We just built a new home and there is no landscaping.  I want to use azaleas for foundation plants.  Our home faces west and we have no shade at this time.  In researching azaleas/rhododendrons I have found several varieties that suggest they prefer full sun.  However, I've mostly been told that this is a "no-no" around here and that the afternoon sun will do them in.  What are the differences between rhododendrons and azaleas?  Could you suggest alternate plants if you feel that azaleas will not work for us?

Azaleas are members of the rhododendron family, and closely related, but they are quite different in ease of care --at least here in Arkansas.  We do quite well with azaleas, but struggle with rhododendrons.  Rhododendrons should never be planted in full sun—they need morning sun and afternoon shade.  For full sun, there are some of the repeat blooming azaleas such as Encore that will take full sun, but they will need ample water.  I would definitely recommend establishing them in the spring, so they have all spring and summer to get a root system in place before winter.  Think about the rollercoaster ride we had this past winter.  In full sun it can make them more susceptible to winter damage.   Some other options for blooming shrubs in full sun include summer blooming spirea, althea or Rose of Sharon, Ninebark, and two that would do well in all but the NW part of Arkansas, Indian hawthorn and loropetalum.

May 21, 2016

I have a 12 year old rhododendron that has just finished blooming and it is 10 ft. tall and very leggy with nearly 4 feet of bare limbs at the bottom. Do I dare try to prune?  How would you recommend.

Rhododendrons are not the most forgiving plants, nor do they rebound quickly, since they often just finish bloom when the weather starts to heat up.  Try to selectively thin out one third of the older growth to a bud or set of leaves down lower on the stem.  Do one third of the branches this year, one third next year and one third the following year.  Follow up with a dose of azalea/camellia fertilizer and keep them watered. Over time you should be able to thicken them up a bit.

April 9, 2016

I live in NW AR. About 4 years ago we planted two rhododendron plants in our yard. One is on the west side of the house and gets no morning sun and filtered afternoon light. The other is on the North side of the house in a bed and receives morning sun but shade in the afternoon. They both have grown and last year each one bloomed, however the foliage of the one on the north has been a pale green since about the first year. They both have buds now so I expect both will bloom. Both have been fed with acid loving plant fertilizer each spring (after blooming last year). The one on the north is sickly looking but continues to grow and bloom. I have turned in a soil specimen for exam but have not yet received results. I’m wondering if too much sun could be the problem. In the past all soil samples have been on the acid side which I thought would be good.

Rhododendrons do need a very acidic soil.  If the pH is too alkaline (too high) it can lead to yellowing leaves but the veins typically are green.  See what the results of your soil sample look like. I would think morning sun would be fine for the rhododendrons. They struggle in hot, dry summers, but they typically either need morning sun or filtered sunlight in order to set flower buds.  Are they both planted shallow? Is drainage the same? Rhododendrons like a well-amended and well-drained soil.  If they are planted too deep or if the soil retains too much moisture they can struggle.  If they are setting flower buds I would say they are getting some of the needed conditions for growth.  After bloom, fertilize and see how they do.

May 2008

I live in Northwest Arkansas and would like to plant some shrubs and trees in my new yard, but I will be leaving soon to spend the summer back up north. Is it ok to plant now, water well and mulch and still have plants left when I return, or should I wait until I come back this fall to plant? Since I am gone all summer, I prefer plants that bloom in the spring or fall. I love azaleas, dogwoods and rhododendrons.

If you plan to leave every summer, then invest in a good sprinkler system with a timer, and have a friend or neighbor check to make sure it is working. While there are drought tolerant plants, it is a rare summer that we can go an entire summer season without supplemental watering. New plants, regardless of their drought hardiness once established, must have regular watering the first year they are planted. I prefer to plant azaleas in the spring and early summer, however, no newly planted plant would survive a month without water in the summer, much less the entire summer, if we have no natural rainfall. Rhododendrons are best planted in the fall, as are dogwood trees. Fall planting is preferable for many plants, but don’t plant any of these unless you have an irrigation system. None of the plants you mentioned are drought tolerant.

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