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

Thread-leaved Bluestar

amsonia-hubrichtii-102212-640

 

 

Bluestar is named for its sky-blue flowers in Spring, but this perennial's month-long display of bright yellow foliage in Fall is its real claim to fame.  Quick:  Think of another Spring-flowering perennial that not only doesn't look tired by September, but that peaks in October.  That doesn't care what soil you plant it in.  That deer never ever nibble.  That thrives year after year after year without deadheading, staking, or dividing.  Indeed.

 

Here's the best of the bunch, the thread-leaf species, Amsonia hubrichtii.  The leaves are as thin as conifer needles, yet soft as fern fronds. 

 

amsonia-hubrichtii-for-close-up-102212-640

 

The foliage is exciting enough to carry an entire garden bed.  Plant a whole bed of thread-leaf Amsonia and it can carry your entire garden.  This perennial doesn't have a bad hair day from the moment it emerges in Spring until you cut the stems down in late Fall. 

 

Truly, if any perennial could be descrbed as perfect, this is it.

 

 

Here's how to grow this essential three-season perennial:

 

Latin Name

Amsonia hubrichtii

Common Name

Thread-leaved bluestar

Family

Apocynaceae, the Milkweed family.

What kind of plant is it?

Herbaceous perennial.

Hardiness

Zones 5 - 8.

Habit

Clumping, with gracefully upright and mounding stems that usually don't need support.  See "How to handle it" for strategies to enhance the plant's self-supporting inclinations. 

Rate of Growth

Medium.

Size in ten years

A clump two to three feet tall and four to five feet wide. 

Texture

Peerlessly delicate.

Grown for

its foliage: Willowy stems are typically unbranched, and bear profuse but still widely-spaced leaves so thin they rival conifer needles in proportion as well as size.  The leaves' airy texture is singularly delicate in hardy perennials, and is only superseded by that of true asparagus—see the vining form of asparagus here—and the non-dwarf forms of some conifers with particularly soft needles, such Pinus strobus.  (Dwarf conifers are dwarf because the interval of leafless stem between leaves is shorter.)  Neither the asparagus nor the large and therefore loosely-needled forms of white pine also provide bluestar's mounding profile and perennial-garden scale.  The foliage is light green until arrival of cooler and even lightly-frosty weather in Fall, when it quickly turns bright yellow.  It holds that color for a remarkably long time—about a month—until stronger frosts become imminent.  Then the foliage is released almost en masse and, seemingly, overnight.  

 

its endurance:  As long as its modest cultural requirements are met, Amsonia thrives year after year.  It also thrives throughout the growing season because its seemingly defenseless delicate foliage tastes terrible to browsers.  Like Paeonia and Iris, Amsonia is a genus of very hardy perennials that gardeners whose property is plagued by deer can confidently explore stem-to-stern. 

 

its flowers: Quickly growing stems pause for a couple of weeks in mid- to late-Spring to bear clusters of starry light-blue flowers at their tips.  To my eye, their blue veers from "light" to "pale and watery," but would be heavenly for gardeners who favor pastels.

 

its restraint:  Although Amsonia is native and sets seed well, in my experience self-seeding is only modest.  Given the plant's usefulness as a full-sun filler, and its appeal to every gardener who doesn't yet grow it, there's the added convenience that these volunteer clumps transplant easily.

 

its tolerance:  Amsonia is not fussy.  It tolerates heavy soil as long as Winter drainage is reasonable.  It also thrives in lean soils, and is also more self-supporting when growing in them.

 

its ease of handling:  In agreeable circumstances, Amsonia needs neither dead-heading, nor staking, nor dividing.  See "How to handle it." 

Flowering season

Amsonia hubrichtii flowers in mid- to late-Spring: The last half of May for me, gardening here in southern New England.

Color combinations

The pale blue of the Spring flowers is charming but ephemeral; the bright yellow of the Fall foliage is prominent as well as surprisingly long-lasting.  The mid-green of the warm-weather foliage of Amsonia combines with everything.  Incorporate Amsonia hubrichtii more specifically on the basis of its Fall foliage instead of its flowers. 

 

Thanks to a wide range of Fall foliage, flowers, berries, and fruit, bright yellow, orange, red, and burgundy are all plentiful, as are vivid blue, purple, and indigo.  Needled evergreens would be texturally repetitive, but fan-spray conifers (anything that looks like an arborvitae) as well as mossy-foliaged conifers, such as junipers, bring a range of other coloristic possibilities, from black-green to yellow-green to blue-grey.  Broadleaved evergreens include those colors, plus widen the options still further by way of variegation.  Amsonia hubrichtii can mingle stylishly with just about anything!

 

Although the lengthy season of the Fall foliage display of Amsonia plus its perky-right-into-hard-frost posture can both offset a great deal of ho-hum in the rest of your garden, you're missing a lot if you don't play with plants whose interaction with Amsonia is active and even inspired.  See "Plant partners" below.

Plant partners

In Summer, Amsonia hubrichtii is a gratifying partner to almost any plant, of any color, whose foliage is contrastingly large, thick, or dark.  The needle-thin leaves are a natural contrast to the inevitably thicker and more leathery foliage of broadleaved evergreens, whether their leaves are small and rounded, like those of boxwood or Japanese holly, mid-size like those of euonymous or species rhododendrons or any of the thorny-leaved hollies, or huge like those of Southern magnolias, and large forms of rhododendron.  

 

If your soil is decent to rich, pair with round- or scalloped-leaved fronters such as lady's mantle, hardy geraniums  or, as in my picture, the glaucous pinnate leaves of Sanguisorba armena.  

 

Purple-foliaged partners are particularly effective, because they point out the light green of the Summer Amsonia foliage, and positively electrify the bright yellow it becomes in the Fall.  The burgundy foliage of 'Bishop of Llandaff' dahlias is unusually frilly, and can seem almost ferny.  Next to Amsonia, it looks contrasting solid and massive.  Depending on how kind your Fall frosts are, you may be able to enjoy Fall Amsonia foliage while the Bishop is still in leaf, even in bloom.  Purple-leaved smokebush is an easy and perhaps ultimate juxtaposition: Its black-purple leaves are round and somewhat shiny, and only intensify in coloring in Fall.  Both the Dahlia and the Cotinus enjoy every bit as much sun as Amsonia; the Cotinus is as friendly to dry soils, too.

 

The unusual longevity of Fall Amsonia foliage raises the question of other plants with similarly lengthy Fall display.  The foliage of Itea virginica can turn burgundy by late September, and can persist into December.  Itea needs normal to good soil, so to avoid pairing with Amsonia that flops miserably, be prepared to cut its stems back by half right after flowering. 

 

Another "early adopter" of burgundy Fall foliage is hardy plumbago, Ceratostigma plumbaginoides.  Consider planting it at the front of Amsonia, whose flexible stems will arch out over it gracefully.  Hardy plumbago continues to flower even with its Fall foliage, so you may enjoy the last of its blue flowers even as the Amsonia foliage flares to yellow. 

 

Another way to bring seasonal blues near Amsonia is to plant asters or mums nearby.  Indeed, by early November they are the only way to bring a substantial intensity of frost-proof indigo or ruby nearby.  Do as I say, not as I do: Pink mums are at the back of my Amsonia colony; thank goodness they are an unusually late cultivar—supposedly 'Last of All'—that misses the bluestar's Fall foliage entirely. 

 

Someday, I'll have the opportunity to plant Viburnum dilitatum 'Michael Dodge' at the back of a large group of Amsonia hubrichtii.  The viburnum bears a profuse as well as showy crop of berries, but in yellow instead of the usual red or orange.  The yellow capsules around the fruits of Euonymus x sarcoxie provides the same opportunity 

 

Amsonia is so self-reliant and so well-behaved that it lends itself to massed plantings of the largest scale.  I remember seeing a coppiced Paulownia tomentosa at Longwood Gardens, standing in a large square bed entirely of Amsonia.  The contrast with the fuzzy heart-shaped leaves of the Paulownia, two feet or more wide in coppiced specimens, couldn't have been more intense.  Chanticleer has a circular bed in its driveway, perhaps twenty-five feet across, planted just with Amsonia hubrichtii and a small grove of (as I recall) bald cypress.  The foliage of the Taxodium was too similarly ferny to that of the Amsonia, but perhaps the goal was that of color:  The bright yellow Fall foliage of Amsonia flooding the ground beneath the coppery orange Fall foliage of Taxodium.

 

Best and grandest of all would be a pairing of bluestar and beech.  Will someone with a ten-acre meadow please ensure that it contains a massive purple beech tree and, at the front, safely in full sun and out of reach of the beech's selfish roots, an eighty-foot swath or—thinking without limit—an eighty-foot circle of Amsonia hubrichtii?  If you must (and it would be fine with me), plant a grove of Hollywood junipers, Juniperus chinensis 'Torulosa', amid the Amsonia.  And then hire the best landscape photographer—ask me for recommendations!—to shoot the meadow once a month from April to December.

Where to use it in your garden

Amsonia hubrichtii is exciting as a specimen amid mixed plantings and also as a large-scale groundcover on the sunny side of even the largest shrubs and trees.  It could also be a stand-alone massed planting in corporate, civic, or institutional settings.  Why not plant the median in a long access road to a campus entirely in Amsonia?  It would need no watering all Summer, and in the Winter could hold plowed snow.  Similarly, a large bed of Amsonia could terminate a sunny residential driveway, accepting the avalanche of plowed snow in February as well as the roasting radiant heat from the driveway in August.

Culture

In Spring or Fall, plant in full sun and in almost any reasonable soil as long as it's not overtly poorly-draining.  Sites and soils prone to dryness are fine.  The flowers are reported as maintaining their already-pale color longer when the clumps get afternoon shade, but growth is more likely to be floppy, and the intensity of the Fall foliage color reduced.  I recommend not worrying about the flowers, which are fleeting anyway, and siting to maximize the Fall foliage display, which lasts weeks longer.

How to handle it

Plant in Spring or Fall.  Thanks to its thick and numerous roots, Amsonia establishes readily.  Plants are drought-tolerant, so need little or no water after establishment.

 

If stems become floppy, omit supplemental watering next season.  If stems are still floppy, cut them back a third or by half immediately after flowering.  If stems are still floppy, you've probably sited the plant in less than full sun.  Consider transplanting to sites with less shade.

 

Stems are best cut to the ground in Fall or Winter; if you wait until Spring, you could be caught by emerging new stems, and would need to cut old ones off one by one.  

How to handle it: Another option—or two!

In my experience, Amsonia hubrichtii self seeds only lightly, and right in the immediate neighborhood.  There is no need to dead-head per se.  The plant is so desirable that you may actually run short of seedlings; look right under the stems of your mother clump, where a few more might be hiding. 

Downsides

In soil that's too rich or too moist or not sunny enough, clumps can become floppy.  This is easy to prevent, as above:  Cut all stems back by half when flowering is through. 

Variants

There are nearly two dozen Amsonia species, nearly all of which are native to North America, and most of those native to the central and southern United States.  Although flowers of A. tharpii can be greenish white, the coloring is typically pale-blue one species to the other.  The main differences are in foliage shape and overall clump size, and can be meaningful only to Amsonia aficionados.  The usual Amsonia foliage is willow-like: pointed, two to three inches long and, more or less, about a half-inch wide.  For my money, the thread-like foliage of A. hubrichtii is so singular as to outweigh potential advantages of other forms, such as A. tabernaemontana 'Short Stack', which is under a foot tall, or A. ciliata 'Georgia Pancake', which might be only four inches tall but twenty-four inches wide.  It's only time to look beyond A. hubrichtii if you already have all of it you could ever want—or if your gardens are so popular with browsers that your other choices in perennials are limited.      

Availability

On line and at retailers.

Propagation

By division and by seed.

Native habitat

Amsonia hubrichtii is native to the south-central United States, and was discovered in the early 1940s by Leslie Hubricht.

 
 
FacebookTwitterRSS Feed

Stay in touch!

 

Sign up for twice-monthly eNews, plus notification of new posts:

 

* indicates required