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Spider Azaleas - A Web of Confusion?

3/11/2024 9:08 am

Spider Azaleas - A Web of Confusion?

Upon moving into my first house in April 1993, I was rudely met with a large grouping of small-leaved evergreen azaleas in randomly mixed shades of red, white and Pepto-Bismol pink. I know some folks like this look, but I am not one of them. So I set about moving them around the perimeter of the back of the property as hedgerows, one side red, the back white, and the other side pink. One year later, with the aid of a chainsaw and shovel, I ditched the Pepto-Bismol pinks altogether. Eventually, I planted intensely and hid all the remaining azaleas so well they stopped bothering me. Well, not entirely, obviously.


When I purchased my current home, I was determined that I would only suffer the neighbors' mishmashes of mixed color azaleas, including the dreaded Pepto pink. Along with scads of invasives, I removed all hints of these small-leaved evergreen azaleas. With a blank palette, I visited my friends at Piccadilly Farm for shrubs. I quickly discovered an attractive plant with lavender flowers labeled "Spider Azalea" - Rhododendron macrosepalum ‘Koromo Shikibu’.  


 Rhododendron macrosepalum ‘Koromo Shikibu’ is a lovely larger-leaved azalea with a flower form very different than your typical azalea. I presume it is the flower shape that leads to the common moniker 'Spider Azalea,' even though the flowers do not have eight petals.


Rhododendron macrosepalum ‘Koromo Shikibu’


It often blooms (sparsely) in the late fall and then heavily in early spring (the first week of March 2024). In mild winters it might even stay evergreen. The flowers have a subtle pleasant fragrance. 'Koromo Shikibu' grows with an open-branched habit, giving peek-a-boo views beyond and reaches 4' tall x 5' wide over time. This plant has been a maintenance-free delight en masse on my steep slope and also on the border with my neighbors (where they block out the view of their tiny evergreen Pepto pink azaleas).


The bright green foliage of 'Koromo Shikibu' forms a lovely contrast to the lavender flowers and remains pretty for all but two or three of the coldest months of the year.



But should you go looking to buy it, is this "Spider Azalea?" Turns out, maybe not. On my next spring visit to Piccadilly, there was a different labeled "Spider Azalea" for sale:  Rhododendrum stenopetalum 'Linearifolium'.


I scratched my head in a web of confusion and then I did what any rational plant-a-holic would do: I bought three. With a similar but much narrower-leaved flower than Rhododendron macrosepalum ‘Koromo Shikibu,’ R. stenopetalum 'Linearifolium' otherwise bares little resemblance otherwise.


The foliage of R. stenopetalum 'Linearifolium' is silvery green and needlelike. The plant needs more sun to bloom and is not nearly as robust as 'Koromo Shikibu'. The bloom time is significantly later too (April for me). I admit I have never bothered to count the petals to see if numbers eight like a spider has legs. 


Theoretically growing wider and taller than the other "Spider Azalea," it has been surprisingly upright and slow growing for me. Three adjacent plants showed very different growth rates through the years, although they have caught up to each other recently.



Rhododendrum stenopetalum 'Linearifolium' in bloom 


 R. stenopetalum 'Linearifolium' in mid-March


So in this tale of two Spider Azaleas, I think that Rhododendrum stenopetalum 'Linearifolium' can be a dramatic standalone plant. But for massing and sheer dependability and beauty, I would highly recommend Rhododendron macrosepalum ‘Koromo Shikibu, which also comes in a white form now. Otherwise, the upshot of this tale of two "Spider Azaleas" is that common names can cause a web of confusion -- even within the trade! 


Should you wish to locate either, as of 2024, Woodlanders was still retailing Rhododendrum stenopetalum 'Linearifolium' and Piccadilly Farms still carries Rhododendron macrosepalum ‘Koromo Shikibu'. And friends who allow visitors to bring shovels are always good sources too.


Contributed by Liane Schleifer