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

Silver-leaved Milkweed

asclepias-speciosa-davis-640

 

This plant may be "normal" if you garden in California, but on the East Coast it's a shocker.  Silver Milkweed has long, pointed, silver leaves (smooth-edged and velvety, too) in pairs up vertical stems.  'Davis' is even more silvery than the straight species; the whole plant glows in the least bit of direct sun. 

 

I've got three 'Davis', just planted this Summer.  This one is planted with the glorious prostrate aster, 'Snow Flurry', which is making a heathery groundcover around the vertical 'Davis' stem.     

 

asclepias-speciosa-davis-aster-snow-flurry-640

 

'Davis' has showy heads of pink flowers.  Fragrant, too.  But even if I only get the silver foliage and the ramrod-straight stems from this West Coast native, I'll be thrilled.

 

 

Here's how to grow this unusual silver-leaved perennial:

 

Latin Name

Asclepias speciosa 'Davis'

Common Name

Silver Milkweed

Family

Apocynaceae, the Dogbane family.  Dogbane, Apocynum cannabinum, is a poisonous (at least to dogs) plant that grows throughout North America—and, no, I've never heard of it.  "Apocynum" is Greek: apo, away; cyno, dog.  "Cannabinum" refers to dogbane's ability to be made into fiber, like true hemp, Cannabis sativa, not any similarity to hemp's foliage or smoke-ability.

What kind of plant is it?

Hardy perennial.

Hardiness

Zones 4 - 10.

Habit

Rhizomatous and potentially wide-spreading, sending up unbranched vertical stems with flowers at the top.

Rate of Growth

Medium to fast.

Size in ten years

A colony of vertical stems to five feet tall; the colony width depends on the culture and climate.  Spreads faster and farther in milder climates.  I'm anticipating modest growth in my New England garden for this strongly-xeric native of the American West even though its native range includes Minnesota to British Columbia, which are much more similar to New England than to its "usual" hot, dry, and unirrigated locales of California.

Texture

Striking.  The vertical stems have pairs of large smooth-edged leaves that in the 'Davis' cultivar are so densely furry they look aluminum-white in the sun.  Growth is sparse and scattered where I've seen it firsthand in the East; pictures of California colonies show thick and dense growth. 

Grown for

its rarity: Asclepias speciosa is widespread in the West; 'Davis' itself is much more of a curiosity.  When I saw it for the first time, in a garden in Connecticut, I was stunned:  This wasn't anything like the all-too-well-named Common Milkweed seen in Eastern America, Asclepias syriacus, with its boring flat-green leaves and scary ability to self-seed everywhere.

 

its foliage:  Smooth-edged and large (to four or five inches or more), the pointed leaves are densely hairy top and bottom, and appear almost blinding white in full sun.  

 

its flowers: dense heads of fragrant flowers, similar to those of Common Milkweed in individual size and overall array at the top of the stems, but a bit deeper pink and, sometimes, in much larger groups.  Very showy, even from a distance.  The Latin name is apt, then: "speciosa" means showy. 

 

its diverse uses in native cultures:  Silver Milkweed seems to be the shmoo of perennials:  Its fiber makes cloth as well as rope.  Its sap (not as poisonous as that of Common Milkweed) can be made into chewing gum.  The leaves, flowers, roots, and stems can all be eaten, and various medicinal brews and teas and poultices can be made from the seeds and the roots.  Now if only the seed-pods could be made into buttons.

 

forage and nectar.  Monarch butterfly caterpillars eat the foliage and store its poisonous chemicals, and so become inedible to predators.  Bees and butterflies love the nectar. 

Flowering season

Spring or Summer, depending on where it's growing.  Summer in a cold-Winter / hot-Summer climate like the Midwest or East.  Spring or Summer in mild-Winter climates like that of California.

Culture

Full sun and dry infertile soil with fantastic drainage.  In the West, this is the plant to grow well beyond the reach of your irrigation system, and in unamended native soil, too.

How to handle it

Asclepias speciosa is described as being extremely xeric, so I'm growing my three test plants in my troughs.  Two are planted in the "dry" trough, where the soil is a third sand, a third vermiculite, and a third actual soil; the third Asclepias is planted in a trough with normally moisture-retentive soil.  In-ground, plant on a slope in full sun, with normal to dry soil.  

 

Cut old stems to the ground in Spring before new growth starts.  If you find that Asclepias speciosa self-seeds too much, dead-head before the seed pods are mature.   

Downsides

Asclepias speciosa is native to the Midwest and West, so may not find

East Coast gardens as congenial.  Self-seeding could be problematic, so you'd need to commit to dead-heading.   

Variants

To my knowledge, 'Davis' is the only Asclepias speciosa cultivar to date, but there are many other Asclepias species to sample.  A. tuberosa is perhaps the easiest, with orange, orange-red, or yellow flowers on long-lasting clumps.  A. exaltata is taller, with large loose clusters of off-white flowers; it's unusual in this sun-craving family in preferring woodland shade.  Rabbits seem to devour it whenever I plant it, but it's native to New York and New England so I'll keep trying.   

 

A. purpureus has flowers that are, indeed, purple—more like a deep raspberry—and a welcome change from the pale-pink flowers of Common (as well as Silver) Milkweeds.  A. incarnata is a moisture-loving species that goes by the common name of Swamp Milkweed; there are a couple of cultivars to try, with flowers pink to white and on plants of taller or shorter height overall.  A. curassavica is a tropical species with showy flower clusters in the same yellow-to-red range (and small-flowers-in-tight-heads configuration) of Lantana; it's an ever-blooming self-seeding perennial weed where hardy, and succeeds as an annual everywhere.

 

The latest darling is A. physocarpa, an African perennial that works as an annual, too.  It's an Ichabod Crane profile—tall and gaunt—but with the blushing shock of inflated round seed pods as big as tangerines, and with projecting hairs all around.  All kinds of common names have resulted:  Balloon plant, cotton-bush, and, most honestly, hairy balls.

Availability

On-line and at "destination" retailers

Propagation

By division in Spring; 'Davis' may also come true from seed.

Native habitat

Asclepias speciosa is native to most of North America west of the Mississippi; 'Davis' was identified first in Davis, California.

 
 
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