How to Grow Azaleas and Rhododendrons

This post will give you many of the basics needed to be successful with growing rhododendrons and azaleas.
Last summer I visited Nova Scotia. On the east and west coasts of Canada, rhododendrons and azaleas flourish. There is plenty of rain and the soil is the rich, acidic soil that they require to grow well.
Rhododendrons can be grown elsewhere. We just have to work a bit harder to give them what they want.
Site Requirements:
Notes on the Atlantic Rhododendron & Horticultural Society suggest that site selection is a key consideration. If the planting area you are considering is wet at any time during the year, it is not a good option. Like so many plants, rhododendron's hate wet feet.
How do you test a site's drainage?
The Society recommends digging a hole and filling it with water. If the water does not drain quickly, select an alternate location.
The Society also warns against planting rhododendrons near foundation walls on the south and west sides of buildings, as they can become hot spots that rhododendrons do not tolerate well. A roof overhang is also an issue, as they can keep vital moisture from getting to you rhododendron.
For more a link with more tips to siting your rhododendron or azalea see my blog post.
The Garden of Duff & Donna Evers
Soil Requirements:
Rhododendrons and azaleas like well-drained, acidic sandy loam ( pH: 4.8-6.0) with lots of organic matter.
Donna Evers, whose garden you see in many of these pictures, passed on this excellent advice about soil conditions that she got from the late Captain Dick Steele, a well respected Nova Scotian rhododendron breeder:
"At first we didn't feed our plants, but then I asked Captain Dick Steele about fertilizing them and he replied, "You feed your kids, don't you?" On his advice we started broadcasting scant handfuls of an all purpose fertilizer (10, 10, 10) over all the gardens. What an improvement it made! We also apply a layer of shredded oak leaves every year. This has improved the soil immensely. Good soil is where it all starts."
Light Requirements:
What do you think: sun or shade for rhododendrons?
Most people think shade, but in reality experienced gardeners like my friend Donna Evers advise differently:
"Despite what the books say about growing rhododendrons in shade, we have found that in our garden they do better with sun. They are more compact and have a better bud set."
A general rule of thumb with regards to light requirements is based on leaf size. The larger the leaf, the less sun is required. Small leafed varieties require more sun. Generally speaking most rhododendrons need at least half a day of sun.
The Garden of Duff & Donna Evers
Start by purchasing healthy plants. In colder areas of North America, rhododendrons are best planted in early spring. The American Rhododendron Society recommends planting in fall for hot areas of the country.
Rhododendrons and azaleas are easily damaged or killed when they are planted too deeply. The top of the root ball should be level with the surface of the ground and planting hole should be larger than the root ball. If your soil is not the light, sandy, acid soil that rhododendrons and azaleas prefer, it is critical to amend the soil with organic matter.
For a link to more planting tips for rhododendrons or azaleas see my blog post.
Rhododendrons and azaleas don't need a lot of care once they are properly established. Mulch your plants with pine needles, oak leaves or wood chips to guard against temperature extremes. Mulching also helps to conserve water.
One great idea is to cut up your tree after Christmas and place the boughs at the base of your rhododendrons. This little bit of added protection will help prevent them from drying out in winter.
Finally, it is best to remove spent flowers as it prevents seed formation and encourages new growth.
Insect and Disease Control
It is a best to seek local advice for the control of insects and disease as problems can vary according to region. Nymphs on the undersides of leaves may cause yellow spotting. Root weevils and stem borer are other widespread pests.
For a link to more tips about insect and disease control, please see my blog post.
The Garden of Duff & Donna Evers
Why grow rhododendrons or azaleas? My pictures answer the question for me.
They're gorgeous!

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Have a question about this project?

2 questions
  • Mary Nighman
    on Jun 27, 2016

    Please tell me about watering a new rhododendron plant? If some leaves are yellowing with brown spots is it too much or to little water?

  • Verna
    on Jun 2, 2017

    Should I apply aluminum sulfate around the base of my old rhodi?
    • Three Dogs in a Garden
      on Jun 5, 2017

      I am going to confer with a friend of mine who has amazing rhododendrons to get you a correct answer. From what I've read you shouldn't not use Aluminum Sulphate to acidify the soil as it leaves build up in the soil and will cause harm to your plants over time. I'll have to get back to you....

Join the conversation

  • Douglas Hunt
    on Mar 15, 2015

    Great advice. I will add that if you don't have the right soil, containers can be the way to go. I remember seeing some pretty impressive azaleas in oversized containers at a botanical garden in Florence. And I have camellias in large pots in my garden because my soil is definitely on the alkaline side and they are doing very well.

  • Hannah V
    on Mar 16, 2015

    Such beautiful flowers.

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