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

Wilson Rhododendron

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Here's the rhododendron that doesn't droop or curl in cold weather.  The foliage of Wilson rhody is perky even if the temperature is below zero. 

 

Just don't think of it as a rhododendron with, well, actual flowers.  Yes, there are the occasional flowerbuds.

 

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But it's a blessing that the small lavender flowers they produce are mostly hidden by new foliage from the stems, such as these, below, that aren't budded for flowers.

 

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Instead, use Wilson rhody as a quality foreground shrub to pair with taller plants whose shins might need some greenery.  I've ringed my topiary of hardy orange with Wilsons, which will help highlight its thickening trunk and flourishing colonies of lichen.

 

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Although Wilson rhodies have a naturally mounding and full-to-the-ground habit, I'll also give my group a little bit of tip pruning.  Over time, they'll grow together to form a shallow and smooth-surfaced dome of foliage beneath the ball of the orange topiary, giving it a solid as well as stylish evergreen base.

 

 

Here's how to grow this exceptional rhodie:


Latin Name

Rhododendron x laetevirens / Rhododendron 'Wilsoni'

Common Name

Wilson Rhododendron

Family

Ericaceae, the Heath family.

What kind of plant is it?

Broadleaf evergreen shrub.

Hardiness

Zones 4 - 6.

Habit

Mounding and tidy.

Rate of Growth

Slow. 

Size in ten years

Three feet high and four across.  Potentially another foot taller and two more feet across.

Texture

Well-behaved and modest.  Dense without looking compressed; full without looking fat.

Grown for

its foliage.  The small pointed leaves hold their shape, color, and orientation all year.  There's none of the drooping and furling in cold weather that can make larger-leaved rhododendrons look like they'd rather be in Miami. 

 

its habit.  Wilson rhodie is compact but still casual, and is usually a bit wider than tall. 

 

its hardiness.  One of its parents, Rhododendron ferrugineum, prefers to grow above the tree-line in its native Alps. 

Flowering season

Late Spring or even early Summer, but the flowers are sparse and small, and are often hidden by new foliage.  Wilson rhododendron is grown for foliage and habit, not flowers.

Color combinations

The green foliage goes with everything.  The lavender flowers are few, and barely visible at best; only the squeamish would worry about pairing Wilson rhodie on account of them.

Partner Plants


Wilson rhododendron is a consistent and hardworking shrub, without peaks or valleys.  Placing it next to plants of similarly unchanging solidity would put everyone to sleep.  Instead, let neighboring plants bring ephemeral flash to Wilson rhodies, while it takes the curse off the gaps between their showy episodes.  

 

Sweet woodruff, Galium odoratum, has no presence in the Winter, but its foamy white flowers and ferny light-green foliage make it a fantastic groundcover on all sides of a Wilson.  It also enjoys the same soil and bit-of-shade exposure.  Large astilbes and ferns at the back bring the same graceful energy of feathery foliage in warm weather, while the Wilson is a dignified placeholder of greenery in cold.  

 

Because Wilson rhododendrons have such constancy, even in Winter, use them as the necessary set-up for deciduous shrubs and trees that can sport colorful bark when it's cold.  Most species that develop colorful cool-weather bark do it best when severely pruned each Spring—and the twigs they grow in response to that pruning are often four, five, and six feet tall.  Wilson is compact enough to work just as well in the front of such plants as at the back. 

 

Even better, plant Wilson rhodies all around a tree with Winter-color twigs that are formed by severe pruning—and, each Spring, prune the tree back to a short trunk, one that's not even as tall as the Wilsons.  Its colorful new twigs will seem to arise directly from the surface of the Wilsons.  There are species and cultivars of boxelder as well as willow that would perform as required.  Leave a narrow access pathway through the Wilsons so you can get right up to the tree to do the pruning.  You'll need access at least twice a year: Once in Spring, for the initial pruning, and a second time in the Summer to snip off any of the new sprouts that are growing too horizontally.

 

If you have a sweep of Wilsons six or eight feet across, you could also allow a clematis to grow across the top of them.  Clematis henryi is particularly good for growing atop low shrubs because its huge white flowers are displayed horizontally.

Where to use it in your garden

Rhododendron x laetevirens is the ideal size and proportion for planting in front of deciduous shrubs that can be tall and wide at the top, but narrow and bare at the shins.  It's also a good choice for foundation shrubs in front of first-floor windows: The shrub will never grow tall enough to need pruning.  Its non-drooping foliage is a welcome contrast in plantings where too many other plants are deciduous or herbaceous in the cold months.  Ironically, athough Wilson rhody doesn't have the pizzazz to be a foreground plant, its compact, restrained, and helpful habit place it at the front nonetheless.  It's the modest and hardworking fronter for bigger, showier, but also seasonally-challenged flashiness behind it.

Culture

Full sun if your soil is good and your watering is faithful.  Safer would be part shade all day, or morning sun with some full shade arriving in the afternoon.  In any exposure, provide humus-rich soil that's acid, or at least not sweet, and is also well-drained.  

How to handle it:  The Basics

For all its toughness and durability after it's established, Wilson rhododendron can be touch-and-go the first year.  Container-grown plants are typically pot-bound, and are slow to extend roots into the surrounding soil no matter how inviting you've made it.  But balled-and-burlaped specimens aren't at an advantage, either.  Instead, they seem peeved that, in the inevitable trauma of being dug, they've lost the same slow-to-explore fine roots that are so prevalent on the container-grown plants.  

 

Prepare the location extravagantly as well as widely; plant Wilsons in a bed, not just in a hole.  Mix in plenty of compost as well as old bark mulch and leaves, all with the goal of creating soil that's moisture-retentive as well as loose.  Be sure that the bed is gently mounded above the surroundings, so water doesn't collect; Wilsons seem to be as phobic about bad drainage as they are about drought. 

 

Score the root ball of containered specimens gently but thoroughly with a soil knife, to break up the film of surface roots and encourage their outward growth into the bed.  If you're planting B&B specimens, handle them gently; place in the hole still tied up, then untie the burlap and pull its flaps outward to expose the rootball itself.  Cut off the flaps.  Feel into the soil around the base of the shrub, gently drawing it away from the trunk, as needed, so that some of the shrub's main roots are almost exposed.  In the process of "balling" B&B plants, it's normal for soil to become mounded up against the trunk; don't be surprised if you need to scrape away (again, gently) an inch or even two of soil.

 

Drench with water and mulch well.  For the rest of the year, worry and wonder if the Wilson is getting enough water.  By the time the leaves droop to show you that, no, it's not, it's usually too late.  If there isn't weekly rain, you must supply it.  The shrubs are sturdy, so watering doesn't need to be gentle or time-consuming.  In the haste of the Summer garden season, I dump a full bucket of water onto the shrub each week, as I'm steaming past for yet other garden urgencies.  If I could throw a bucket's-worth of water at it, instead of having to stop for those two seconds to up-end the bucket, I'd have done that instead.  The shrub doesn't care, and is grateful for the water no matter how suddenly or heavily it's delivered.

 

If the shrub looks perky as it enters its second Spring, you've probably succeeded in establishing it.  This second Summer, throw a bucket of water at the shrub twice a month July to October; the third Summer, it can usually handle its affairs independently.

How to handle it: Another option—or two?


The part shade that makes Rhododendron x laetevirens easier to establish also encourages looser growth.  The shrubs don't "fall apart" the way, say, daphne does, but growth becomes denser if early each Spring—or even in late Winter—you cut off any branch tips that have poked above the general canopy of foliage.  

 

With sun that's nearly full, growth is so attractively dense—and all on its own, too—that it's worth it to grow Wilson rhodies in the best possible soil, and to water as needed, to make that full-sun siting possible. 

Quirks or special cases

None.

Downsides

Wilson rhododendron will horrify anyone who expects rhododendrons to put on a big and bright show of flowers; its small lavender flowers are in stingy clusters that are sometimes hidden under new growth.  And there are not many of them in the first place. 

 

For all its toughness and durability after it's established, Wilson rhododendron can be touch-and-go the first year. 

Variants

While there are thousands of cultivars, species, and hybrids of  rhododendrons at large, R. x laetevirens is unusual in not having any siblings.  Its parents—see below—are garden-worthy in their own right, but not superior.   

Availability

On-line and at retailers.

Propagation

By cuttings.

Native habitat

Rhododendron x laetevirens is a hybrid of R. minus Carolinianum Group, native to the Appalachian Mountains of the Carolinas and Tennesee, and R. ferrugineum, native to the Alps.

 
 
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