Over the years I have installed a few thousand Rhododendrons in an assortment of landscapes from Naperville to Frankfort to Chicago and points in between.
I use a core group of Rhododendron that I know will work based on my field experience. That experience includes great success with some varieties and woeful failure with others.
That being said, just for kicks I recently went through The Manual Of Woody Landscape Plants, Dirr, Mike, 2009. He lists over 200 varieties that are hardy to USDA Zone 4. While some may be difficult to locate in commerce, some are easily found and awesome additions to a woodland garden or shady landscape.
I have broken them down into five groups for ease of listing some of my favorites that will work wonderfully in a residential landscape:
- Catawba Rhododendron (Rhododendron catawbiense): ‘Boursalt’, ‘English Roseum’, ‘President Lincoln’, ‘Purpureum Elegans’ and ‘Roseum Elegans’ are splendid cultivars. All from this group are evergreen.
- Rhododendron ‘Exbury’ and ‘Knaphill’ hybrids: While many are hardy to -20 degrees Fahrenheit they have been supplanted for the most part by the next group which is even more cold hardy.
- The Northern Lights Series: Includes a colorful array of options that are hardy to between -30 and -40 degrees Fahrenheit. ‘Apricot Lights’, ‘Lemon Lights’, ‘Mandarin Lights’ and ‘Northern Hi-Lights’ are my favorites from this series. All but Mandarin Lights are fragrant as well. These are all deciduous.
- Gable Hybrids. Most of the Gable hybrids are referenced as azalea. ‘Herbert’, ‘Karen’, and ‘Stewartsown’ (Stewartstonian). Karen and Herbert are strong purples and Stewarts is a dusty, brick red. These are semi-evergreen.
- Rhododendron yedoense var. poukhanense: Unfortunately, it has no catchy common name. This is the one I use the most as it has been reliable, sturdy and vibrant. It has soft lavender blooms in May and I have it on projects that are nearing twenty years old.
Rhododendron WILL work in Chicago landscapes as long as you are using the right ones. For cultural information refer to my previous blog about Rhododendron and their cultural requirements. Pictured below is ‘Roseum Elegans’ in all her purple glory.