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

Prairie Dock

 

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To get eye-to-eye with this daisy, even your eight-foot stepladder might be too short.  Prairie Dock perches its flowers atop thumb-thick stems that stretch skyward to twelve feet.  Who knows why?  Perhaps growing as it would amid a sea of prairie grasses and other prairie perennials—there are almost no indigenous shrubs or trees in true prairies—Prairie Dock's flowers would be the tallest in the whole zip code.  All the easier to be seen by pollinators as well as by the birds that eagerly devour, and therefore help to spread, the resultant seeds.

 

Seen across the treeless, shrubless plains, these flowers would have been visible for hundreds and hundreds of yards.

 

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The flowers top thick and wiry-strong stems.  With few leaves to catch the wind, they can stand reasonably upright regardless of prairie storms. 

 

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That's the top of my yellow eight-foot ladder; I'm shooting from my other step ladder, a mere six footer.

 

All the way down at ground level, huge, thick and leathery leaves to four feet tall would have no trouble piercing any overhead thatch of grasses to grab all possible sun.  As clumps mature, there are enough leaves that the outer ones can splay outward, smothering anything within reach, to ensure that the central leaves are never in shade. 

 

My clump is both young and recently-transplanted, so the leaves are barely a third their mature size.

 

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In the Summer-drought climate more typical of the prairies than New England's occasional drenching storms, Prairie Dock establishes slowly but solidly, rooting many feet down into the soil.  With such a deep anchor, the thumb-thick flower stems are fully self-supporting.  In the rich and comparatively moist soil in my garden, though, a bit of staking is a help to keep the stems fairly vertical.  When you're twelve feet tall, just a bit of a slant at the ground can mean four or five feet of outward splay at the top.   

 

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The stake needs to be strong, but it doesn't need to be tall.  Pound it a foot and more into the ground but leave only two feet above-ground.  Then you can tie just the ankle of the flexibly strong stem to the vertical and let the upper yards of it wave about with casual but secure erectness.

 

 

Here's how to grow this extraordinarily tall and tough perennial:

 

Latin Name

Silphium terebinthinaceum

Common Name

Prairie Dock

Family

Asteraceae, the Aster family.

What kind of plant is it?

Flowering perennial.

Hardiness

Zone 4 to 8.

Habit

Upright and clumping.

Rate of Growth

Slow to establish, but then vigorous and fast.

Size in ten years

A clump three feet across and, when just in leaf, to four feet tall.  In bloom, up to twelve feet tall.

Texture

The erect basal foliage is immense and banana-like, for a unique tropical look from an extremely hardy species.  (It may also remind you of the leaves of the huge weed burdock, Arctium lappa.) The vertiginously-vertical flower stalks are almost leafless and soar to up to twelve feet.

Grown for

its erect foliage, mostly basal, where the individual leaves are banana-like in presence, and up to four feet long.  This perennial is large enough to look shrub-like when the clump is full and mature. 

 

its flowers and flower stems.  Three-inch yellow daisies peer down at the rest of your garden from their perch atop thick vertical stems that can be ten to twelve feet tall.

 

its toughness.  This prairie native shrugs off deep-freeze winters, scorching bone-dry summers, high winds, and even brushfires.     

Flowering season

Summer: August here in Rhode Island.

Culture

Full sun and almost any soil.  Faster and larger in richer soil with enough water—but then can also need a bit of staking. 

How to handle it

Prairie Dock is very long-lived, and its thick taproots can delve down to twelve feet (!), so this is a perennial for long-term siting.  Clumps do survive transplanting even though this inevitably severs most of the thick roots.

 

Although the flowers can be twelve feet high, resist the tendency to think of this as a back-of-the-bed plant.  This perennial is remarkable tip to toe, from those stratospheric flowers to their thumb-thick stems—yard after yard of them—right down to the gigantic leathery basal foliage.  Site it where you can see everything.  Because the flower stems are just about leafless, they don't block your view of anything in back of them.

 

Draw even more attention to this perennial's enormous banana-like leaves and bizarrely-tall flower stems by surrounding it with low and ferny companions that also appreciate plenty of sun, and don't care if the Summers are dry and the Winters can feel like Siberia.  Winter Jasmine, Jasminum nudiflorum?  Or a surf of Rhus aromatica 'Gro-Low' ?  Or if your soil's decent-to-rich, Amsonia tabernaemontana in any of its really thin-leaved forms.  Or if you've got great soil and don't mind a bit of Silphium staking, go for big ferns like Matteuccia or Osmunda

 

And if at all possible, highlight the flower stems by having high and dark-green bushes in the background.  This is the time to dedicate yourself to growing that twelve-foot-tall yew hedge!    

Downsides

Silphium terebinthinaceum is, in my experience, remarkably self-controlled, neither self-seeding nor spreading widely underground.  Yes, it can need a bit of staking.  But all in all, this is an exceptionally easy, long-lived, and trouble-free perennial.

Variants

There are a half-dozen and more Silphium that fans of Summer gardens should be tempted by.  Some have foliage as striking as Prairie Dock's, with huge but ferny leaves, or very large leaves paired up tall stems.  The

semi-single daisy flowers are nearly always chrome-yellow, so these are not the perennials for gardeners who insist on pale sophistication at the expense of full-throated drama.   

 

The smaller-leaved varieties can be pinched for shorter growth and later flowering, but the large-leaved varieties must be accepted on their own terms, at their own height.  If you crave yellow daisies on perennials shorter than eight feet, look into the Rudbeckia, Heliopsis, Telekia, and Helianthus genera. 

 

All the Silphium share the hardiness and tolerance of heat and drought of Prairie Dock, as well as its longevity.

Availability

On-line, especially from specialists in prairie species, and sometimes at "destination" retailers.

Propagation

By division in Spring, as well as by seed.  For such a large and diverse genus, Silphiums are strikingly lacking in hybrids, which wouldn't normally come true from seed.

Native habitat

Silphium terebinthinaceum is native to the American Midwest.

 
 
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