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a mad scientist, searching out plants that most people have

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…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

 
 

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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

Purple-Stemmed Himalayan Box

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Sarcococca: Shrubs to grow as much for their fun-to-say name as for their many garden-worthy qualities: elegant and deer-proof foliage, dense and groundcovering habit, preference for shade, and small but penetratingly-fragrant flowers in late Winter and Spring.

 

What the genus doesn't offer is coloring beyond green and white, lovely as they are. Except this form: Sarcococca hookeriana var. digyna 'Purple Stem'. The new stems are reported to be a soft burgundy; so far, I live in hope. My colony is still in its first year, and was not planted until June; perhaps the purpling is only present earlier in the Spring.

 

'Purple Stem' spreads—gleefully if the picture below is any indication—via underground runners. The three in the picture are six inches and more from the mother ship at the left. At this rate, 'Purple Stem' will form a groundcovering sweep quickly. Sometimes its eagerness is too much of a good thing; see "Partner plants," and "How to handle it: Another option," below for suggestions for plants that welcome what can be an incoming tide of Sarcococca growth, and what to do if—oops—a neighboring plant is one of many that might be swamped, instead.

 

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Late Winter and early Spring is a peak time for Sarcococca, when tiny buds that have been largely hidden from view under the leaves open.

 

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They form small flowers, usually white but, reportedly, pinkish for 'Purple Stem', whose real talent is a sweet and far-ranging fragrance.

 

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I'm so tall that the fragrance tends to hang around my knees; all the more reason for me to kneel down in respect of this eccentric and hardworking shrub.

 

 

Here's how to grow this elegant groundcover:

 

Latin name

Sarcococca hookeriana var. digyna 'Purple Stem'

Common name

Purple-stemmed Himalayan box

Family

Buxaceae, the Box family.

What kind of plant is it

Evergreen groundcovering shrub.

Hardiness

Zones 6 to 9.

Habit

Dense, multi-stemmed, and surprisingly vigorous as a stoloniferous colonizer.  

Rate of growth

Medium.

Size in ten years

Two to three feet tall; maximum height isn't usually reached at the cold end of the hardiness range. Colony width is indefinite and, in a decade and with ideal conditions, could reach six feet or more.

Texture

Medium and consistent. Mature Sarcococca colonies are typically uniform in contour and density, forming a layer of groundcovering greenery like the worlds highest, thickest, and most tasteful shag rug.

Grown for

its evergreenity and habit: All forms of Sarcococca are elegant and effective groundcovers, whose growth is dense enough, both in stem and foliage, to be virtually weedproof year-round. The shrubs' above-ground restraint belies vigorous underground stoloniferousness. If you have ever dug up a clump of Sarcococca, you'll think its white, profuse, and outward-racing stolons had been borrowed wholesale from dwarf bamboo.

 

The foliage doesn't curl, drop, or otherwise recoil from Winter cold, although this, in turn, is one reason that most forms of Sarcococca are not hardy colder than Zone 7. Its solidly-Zone-6 hardiness makes Sarcococca hookeriana var. digyna welcome; the humilis variety is hardier still, into Zone 5.

its colorful stems: These are burgundy-flushed when young, but, candidly, it's a subtle display. Only if you've had exposure to other Sarcococca forms, and have experienced first-hand that green is the idée fixe of the genus, will the occurrence of any other color be notable.

its fragrant flowers: small and largely hidden under the leaves, the arrival of Sarcococca flowers is usually perceived first by your nose. The fragrance is sweet not citrusy, hence the common name, "sweet box."

 

its steadiness and endurance: My clump's enthusiasm notwithstanding, Sarcococca is usually a bit slow out of the gate. Nonetheless, with only reasonable attention during its first two years of establishment, it will form a uniform groundcover that doesn't thin or flag year after year.

 

its imperviousness to browsers:  As is typical for plants in the Buxaceae family, Sarcococca foliage is normally not foraged.

Flowering season

Late Winter and early Spring: March into April here in New England. 

Color combinations

The modestly-purple stems can mingle with anything; the flowers are sometimes shown as being pink, or at least pinkish, but other times they are described as white. Given their position beneath foliage, their color matters less than their lovely fragrance. Sarcococca can associate easily with any color. 

Partner plants

The dense texture and uniformity of a colony of Sarcococca is achieved, in part, because of the shrub's impressive and even thug-like stoloniferousness. Few herbaceous plants can compete with Sarcococca; I have seen it smother even hostas, normally the nuclear option for groundcovers in shade.

 

Its evergreenity is also, oddly, a limitation. Almost any other evergreens—whether broadleaf or coniferous, large-leaved or small—can seem oppressive.

 

Shrubs with a full-to-the-ground habit are liable to look as if they were sinking into a Sarcococca sea; avoid pairing with weigela or spirea. You should already avoid pairing with mounding forms of rhododendrons and azaleas, on account of their repetitive evergreenity.

Instead, pair with tall deciduous shrubs and small ornamental trees, where the thorough evergreenity of sweet box frees you to plant otherwise appealing species whose Winter appearance might be sparse or bare, or whose shins and ankles need covering up year-round. These taller and, often, simply larger plants will also have somewhat deeper roots, which will be less likely to be in as direct competition with the dense, shallow, "category killer" roots of Sarcococca. These large companion plants often grow from strong vertical stems arising from the base, or directly from the roots; they not only look, pleasingly, like they have pierced through the dense "mattress" of Sarcococca growth easily, they actually have. Handily, this vertical habit near the ground often combines with a spreading upper canopy, to  create just the partial shade that Sarcococca enjoys. In turn, a bulky, spreading, and eventually large colony of Sarcococca at the base gives these top-heavy shrubs a visual anchor that feels appropriately wide, thick, and heavy. If you're planting any viburnums, deciduous azaleas, fancy maples or willows or alders, cornuses, aralias, kolkwitzias, lilacs, clethras, calycanthus, or hydrangeas, you're probably creating prime habitat for Sarcococca

 

Because the Sarcococca foliage and look is constant year-round, choose partners that can provide lengthy seasons of contrast. Variegated or contrasting-shaped foliage is always the right choice. 'Lemon Wave' hydrangea, then, instead of a plain-green form. Other choices covered here include Viburnum lantana 'Aurea', Acer circinatum 'Pacific Fire', Alnus glutinosa 'Imperialis', Fagus sylvatica 'Ansorgei', Liriodendron chinense, and Populus alba 'Richardii'.

Where to use it in your garden

Sarcococca is a delicious oddity in Zone 6 and 5, where its ability to carpet beneath deciduous shrubs makes it a relief from pachysandra, vinca, and ivy. There are so many low evergreen shade-tolerant groundcovers in Zones 7 and warmer—where Sarcococca thrives, and so many other forms of it are hardy—that, ironically, the shrub is less valuable despite its ease and vigor and diversity, and therefore less appreciated.

Culture

Part or even heavy shade in any reasonable soil that has decent drainage, especially in Winter. Growth is faster and stronger in soil that is humus-rich, loose, moisture-retentive, and nutrient-rich soil; established colonies are impressively drought-tolerant.

Mulch young shrubs well, so as to retain moisture and also provide easy cover for the stolons. As is typical for broadleaved evergreens, Sarcococca will not tolerate wet feet, especially in the Winter.

How to handle it: The Basics

Plant in Spring. Nursery stock are pot-grown and, given the outward enthusiasm of the Sarcococca stolons, the root ball will probably look (and be) pot-bound. The stolons loosen easily; as you plant, take care to keep them spread out. This will help the shrub establish itself, by exposing its current growth to a literally wide-as-possible expanse of soil and amount of moisture. It will also help the colony increase in size, because those outrigger stolons will, at least for their first season, have their surrounding soil all to themselves.

 

Take care to water as needed to ensure establishment. The growth of Sarcococca is naturally dense, so there's a lot of foliage and stems for the roots to keep hydrated. Established colonies are impressively drought-tolerant, but new plantings are at risk, especially if planted where sun can be strong, even if for only part of the day. Generous soil preparation and attentive first-season watering are better tactics for establishment than planting in otherwise unnecessarily-deep shade. 

How to handle it: Another option—or two?

Groom the colony in late Winter or early Spring to remove any Winter-killed portions. This need lessens as the colony establishes; it isn't needed at all if the colony has been sited in congenial habitat in the first place. An on-your-knees visit in early Spring is a good idea, regardless, because then you'll have the strongest exposure to the flower's scent.  I'm 6'3" and, when standing, I'm too tall to notice the fragrance unless the air is very still. The fragrance is worth kneeling for.

 

If you need to prune just to control the height of your colony (and in that happy event, congratulations for gardening in a mild-enough climate), do so right after flowering is finished. Then you haven't reduced the intensity of the flowering (and, more important, the resultant fragrance), and you've also given new growth the maximum length of growing season in which to mature and harden-off in the face of the coming Winter. 

 

If you haven't been able to surround your Sarcococca colony exclusively with shrubs and small trees that don't mind the increasing in-flow of the tide of Sarcococca growth into their immediate territory, some day you'll need to control the colony's extent. The runners are shallow and readily visible, but if the colony has thoroughly infiltrated to the core of an at-risk plant, it can be difficult or even impossible to extract Sarcococca runner by runner. You may have to dig up the plant you're trying to save to free it from the Sarcococca. Then replant it where it's out of reach, and plant something more Sarcococca-appropriate (see "Partner plants," above) in its place.

 

It's much easier if you control Sarcococca long before it has wandered into the heart of an at-risk neighbor—when it's only halfway there, in other words. Then, you can use a spade or soil knife to make a vertical incision through the Sarcococca colony. It's easy to pull up runners that are now beyond that "line in the sand." Few gardens have all the effective groundcovers they need; if you do complete the edging of your Sarcococca colony in early Spring, you can replant the outlying portions near shrubs and small trees beneath which they can effectively and congenially create new groundcover.

Any (other) quirks or special cases?

None.

Downsides

Downsides? As long as it's not challenged by Winter, Sarcococca is hard to beat.

Variants

There are around a dozen and a half species of Sarcococca; with hybrids and other forms, a sarcococcaphile could have a collection of two dozen and more. But only a sarcococcaphile would want to: the forms don't differ dramatically enough to warrant using more than a few in any one garden, no matter how extensive. The foliage is always both evergreen and green, more-or-less shiny, and pointed; the habit is usually stoloniferous; flowers are nearly always white, small, and fragrant; berries are black and only modestly showy; preferred habitat is shaded.

 

Sarcococca forms differ chiefly in height, from the height of pachysandra to the height of a small tree; hardiness—from Zone 9 down to Zone 5—is roughly in reverse proportion to height. Although popular in gardens for well over a century, no forms with colorful foliage have been found or produced. 'Purple Stem' is doubly rare in having even subtle color in its stems as well as its flowers.

 

If you're gardening in Zone 5, Sarcococca hookeriana var. humilis is your only choice. It's the shortest of the bunch, but every Sarcococca is a beauty. If you're gardening in Zone 6, consider growing 'Purple Stem', too. It could become twice as tall, three times if you're lucky. If you're in Zone 7, the opportunities are broad indeed, but while the shrubs are taller still, they aren't otherwise more diverse. Grow them as filler—as fragrant, never-less-than-tidy, elegant padding around and beneath more seasonally showy plants—so your garden won't become "over-cocca'd."

Availability

On-line.

Propagation

By division and by cuttings.

Native habitat

Sarcococca hookeriana is native to the western Himalayas and Afghanistan; S. hookeriana var. digyna is native to western China.

 
 
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