Louis Raymond experiments in his own gardens like

a mad scientist, searching out plants that most people have

never seen before & figuring out how to make them perform.- The Boston Globe

…Louis Raymond ensures that trees can grow in Brooklyn…

or just about any other place where concrete consumes

the dirt and skyscrapers shield the sunshine.- USA Today


NEW Trips to Take!

Myrtle's easy when the conditions are right.


NEW Plants to Try!

Louis tries to capture the exact words to describe the fleeting but deep pleasures to be found in these Summer-into-Autumn incredibles.


New Gardening to Do!

Allergic to bees? You can still have an exciting garden, full of flowers and color and wildlife.


Plant Profiles

Pennsylvania rhododendron



What a shock—in a good way—to be able to have any rhododendron be a part of the garden's Summer peak.  'Pennsylvania' doesn't let Spring tempt it into bloom.  (Then it would be just another rhododendron.)  It waits until July!


Getting six to eight feet tall, it's a shrub you can plant towards the back of even the deepest beds.  My youngsters, though, are barely to three feet.  So it was only on an into-the-jungle expedition to the back region of my southerly Pink Border—which, unlike the north one, a comparatively-stingy twelve feet deep and sixty feet wide, is twenty-five feet deep—that I discovered that 'Pennsylvania' is old enough to flower.  Hooray!




Stems need to be two years old to start blooming.  Notice the top of the bush: last year's stems are brown-barked while this year's are still green-barked.  But no flowers until farther down, from branches that were growing a year or two before the top had even sprouted.  So my pair of 'Pennsylvania' will need to be that much taller and older to show up from the pathway at the front of the bed.


Or I can get in the habit of leading into-the-jungle treks to the back of the bed. 



Here's how to grow this Summer-surprise shrub:


Latin Name

Rhododendron 'Pennsylvania'

Common Name

Pennsylvania rhododendron


Ericaceae, the Heath family.

What kind of plant is it?

Deciduous hardy Summer-flowering shrub.


Zones 5 - 9.


Dense and broad, like a typical azalea.  Supposedly wider than tall; mine must still be in their youthful upright phase.

Rate of Growth


Size in ten years

Six feet tall and six feet or more wide.  Eventually to eight feet tall and wide.


Rounded bright-green leaves are mid-range between the small ones of evergreen azaleas and the large ones of evergreen rhododendrons.  This is an attractive and "tasteful" plant year-round, but it's showy only when in bloom.

Grown for

the surprisingly late flowers.  Clusters of six to eight bright pink flowers with a bit of orange in the center, and with showy and very long "eye-lash" stamens.  These are classic azalea flowers, and, frankly, only medium-sized ones at that—but they don't start appearing until the middle of July!  Plus, they're (mildly) fragrant.


the solid hardiness.  'Pennsylvania' is one of many bone-hardy rhododendron hybrids developed at Weston Nurseries, in Hopkinton, MA, in response to a particularly ruthless Winter in the 1930's. 


the ease of culture.  Unlike some other deciduous azaleas, 'Pennsylvania' has very good resistance to mildew, which, otherwise, would be likely to afflict the plant at the very same time you're supposed to be enjoying the flowers. 


the foliage gets a nice Fall color, too.

Flowering season

High-Summer:  The middle of July into August.


Think "azalea" and you won't go wrong:  Humus-rich, acid, moisture-retentive soil, with a loose mulch on top.  Part-shade to full sun.  Not a plant for drought stress or for lean soil.  

How to handle it

'Pennsylvania' needs little attention after it's established.  It's naturally bushy, so doesn't need shaping or pruning to get off to a good start.  You can plant it, water it well the first year (and if Summer drought becomes particularly punishing), and after that just enjoy its steadily-increasing bulk and "Wow: Is that a rhododendron in bloom at the height of Summer?" floral display.


None I can think of.


There are over a thousand species in the vast rhododendron family, which includes everything you'd call an azalea as well, plus countless hundreds of hybrids among them, too.  As with the similarly-enormous rose family, flowers can be had in almost any color but true blue, from white to pink to yellow to orange to deep red.  There are a number of the 'Pennsylvania'-type rhododendrons as well, all of which are especially hardy (sometimes into Zone 4), deciduous, and very late-blooming. 


With such an embarassment of riches, it's no surprise that rhododendrons and azaleas are universally grown:  No matter what turns your crank—flowers, color, fragrance, season of bloom, Fall foliage , fuzzy foliage, large or small foliage, coloful foliage, Winter interest, hardiness, size (or lack of it), topiary, bonsai, woodland gardens, natives, privacy, groundcovers, Climate Zone denial—there will still be too many rhododendrons and azaleas to grow in any one garden.


On-line and at retailers.


By cuttings.

Native habitat

'Pennsylvania' is a hybrid developed in Massachusetts, of R. prunifolium, native to Georgia and Alabama, and R. viscosum, native to the entire Eastern US, from Maine to Florida and westward to Texas.

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