Rent Shop Volunteer Join

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Share

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants
See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

 
rate this answer
Not Yet Rated

Tuesday - July 12, 2011

From: Southampton, NJ
Region: Mid-Atlantic
Topic: Pruning, Shrubs
Title: Pruning smooth azalea in NJ
Answered by: Anne Bossart

QUESTION:

I have a Smooth Azalea growing in my woods. It was verified by the Master Gardeners of Burlington County New Jersey. It's 12 feet tall and lanky. Can it be trimmed in hopes of thickening up? If so, any tips on trimming it?

ANSWER:

What a great find!  I am sure the Master gardeners can give you pruning advice as well, but yes, with careful pruning you should be able to sculpt your shrub and thicken it to a degree.

Rhododendron arborescens (Smooth azalea) is a deciduous azalea which means that it can tolerate (and in the north, require) more sun than its evergreen relations.  If it is not flowering well, its lankiness could be as a result of not enough light.  You don't mention how thick your woods are.

If you decide to prune it, there are two things you must remember: never cut back more than one third of the plant in a growing season, and pruning stimulates growth.  The one third rule means that you can cut back all the branches one third or you can prune one third of the branches to the ground.  The pruning stimulates growth rule means that wherever you cut, that is where new growth will appear.  That is why you sometimes see shrubs that have been sheared to a globe or square shape that are green only on the surface of the plant and have crazy shoots sticking out all over.

So examine your plant carefully and before you make each cut, try to picture how the plant will look without that branch and also realize that exactly where you cut it is where the new growth will appear.

Check out this video on YouTube and watch a demonstration of rejuvenation pruning on some large deciduous azaleas.  That is; one year they cut back one thrid of the branches to the ground and new branches grew from ground level, the second they cut another third and the final year they cut out the last third.  This makes the plant seem juvenile again.  Note that the plants they are demonstrating on are growing in an open, sunny area.

I would also recommend David Joyce's book: Pruning and Training Plants.  It is a great reference for doing all sorts of pruning and it has diagrams.  I am a big believer that a picture is worth a thousand words so it will likely be more helpful than my description.

 

From the Image Gallery


Smooth azalea
Rhododendron arborescens

Smooth azalea
Rhododendron arborescens

Smooth azalea
Rhododendron arborescens

More Shrubs Questions

Difference between Styrax platanifolius and Styrax patanifolius ssp. texanus
November 18, 2011 - What is the difference between a Styrax platanifolius and a Styrax platanifolius texanus?
view the full question and answer

Deer resistant plants for Trinity, TX
March 23, 2013 - I need a list of deer resistant flowers, herbs and plants that would could be planted in Trinity, Texas.
view the full question and answer

Non-blooming or fruiting Oregon grape holly in Elmhurst IL
May 14, 2010 - I have an Oregon grape holly bush that has never bloomed and has never had fruit. I have had the bush for at least 6 years, it is approximately 5 ft tall. Have had no problems, just no flowers/fruit....
view the full question and answer

Foundation plants for Albuquerque.
July 01, 2012 - Hello, I live in Albuquerque. I am looking for some native/xeric low water usage plants for foundation plants for my home. They will be foundation plants for a two story home that has a large ponde...
view the full question and answer

Small drought-resistant shrub for northeast Texas
June 23, 2009 - I am replacing the formal hedge of hollies along the front of my house and was planning to use mostly Inidan Hawthornes, but now I'm reading that they are very prone to disease, are there any low gro...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.