Seven Solutions to the
"Too-Big" Rhododendron

by Cass Turnbull

The problem with rhododendrons is, well, they're touchy.  Sometimes you head back a branch to a node, and when you return next month you find that, instead of sending out new shoots, the branch simply gave up and died.  On other occasions people reduce their rhodies to the height or width they want, only to discover that by the time the plants have developed decent, full leafy crowns, they're back up to about the size they were before.

The hardest plants to prune are old previously chain-sawed rhododendrons.  The new growth looks like spaghetti.  Although many can be brought back to a semblance of beauty with years of rehabilitative pruning, these casualties are often so indisputably ugly that removal is a more realistic solution.  Just to confuse matters, radical reduction sometimes results in growth which is bushy, compact, healthy AND shorter.  Much depends on whether the species in question is healthy, and of a compact habit to begin with, and whether it receives sufficient sunlight to re-establish.  Another commonly seen situation is that of a large-growing, open habit rhododendron which someone is trying to keep shorter and more compact.  The hapless pruner tries in vain.  Even when following the "rules" by selectively heading back branches to shorter laterals, the result is a "funny-looking" plant, which is to say it starts to grow in a roughly v-shaped pattern.  With the above caveats in place, let's review seven solutions to the too-big rhododendron.

1) Prune it.

Most people think their rhody is too big, but really it's just too oppressive and/or crowded.  Real pruning for health and good looks often solves the problem.
The horticulturally correct pruner takes out all the dead wood.  Do this first and always.  Prune out a few of the worst rubbing-crossing branches.  Often it helps to take off some of the lowest branches, slowly working up and out from the inside.  Also concentrate on thinning out the worst, most interfering branches which crowd into nearby shrubs, the house, the window, the gutter, or the walkway.  See if that just doesn't do the trick.

2) Move it or the bed it's in.

Given the touchy nature of the beast, it is often a better and longer lasting solution to increase the shrub bed size to accommodate the plant.  This is a creative but unpopular solution due to removal of sod involved.

Rhodies have broad, flat, fibrous root systems and are a relative dream to move.  Landscapers often move plants that are larger than people.  It may require up to four strong backs and a tarp to slide the offending rhody out of its present home and to its new one.  Don't be afraid to cut off 50% or more of the roots, both large and small.  Immediate watering, and lots of water throughout the first year is essential.  Moving is the only logical solution for situations where shrubs have been planted too dose together to begin with --- as commonly seen in new landscapes everywhere.

3) Selective reduction.  Is it under the window?

You can try to "work back" your rhody.  You thin and shorten a little every year.  Locate the tallest branch and follow it down inside the shrub to where it meets a lower and shorter lateral.  Cut it off there.  Repeat with the next tallest branch Continue until you sense you've gone too far.  Quit, then come back next year.

4) Stop it in its tracks.

If the plant in question borders high traffic areas---paths, stairs and such, you might try snapping off the new growth.  After the plant has finished blooming you can either pinch out the new end-bud, or let the new supple shoot extend and snap it off with your fingers soon thereafter.  Landscapers attest that this will not prevent blooming next year, though it is hard to understand why not.  It is also exceedingly time consuming and must be done every year to restrict growth.

5) Arborize.

On special occasions a "too-big" rhody can be thinned-up and turned into a nice small tree.  The plant in question should be very big and old.  It should have a thick, curvaceous trunk.  Be sure to meticulously deadwood it as well, and perhaps generally thin the upper canopy to prevent the 'lollypop" look.

6) Radical renovation.

In especially desperate and hopeless situations, it is sometimes appropriate to cut the entire plant nearly to the ground and start it over.  Like surgery, it is a serious move and you should exhaust other possible solutions first.  Sometimes the plant dies.  Most often it does not.

Renovation works best on old and/or previously mal-pruned shrubs.  It will take several years to recover and look like anything.  It will still need almost as much room to live and look good.  Do it in the early, spring.  Do not fertilize.  Water well throughout the next year.

7) Adjust your attitude.

Most often the only thing a rhododendron is too big for is somebody's idea of how big it should get to be.  In this case, the cheapest and best solution is to learn to appreciate "mature" plants.  A mature rhododendron can grow to be ten to twenty feet - that's two stories high.  And some get up to forty feet.  Get used to it.


From Plant Amnesty - with permission. Take a look, this Seattle area site has lots of good information!