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

Cape Lilac

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The flowers of Cape lilac are slow in coming, late October into Winter, but so worth the wait.  Large pinkish-white panicles of buds develop at the end of every stem, from which—not quite at the tip, but at long last—lilac-and-blue flowers emerge.

 

The coiled stamens unfurl to their shout-of-joy upward extension, giving the flowers a "soprano trilling her top notes" profile.

 

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The first flowers to open are from the buds that are connected directly to the panicle's main stem.  New buds and new flowers develop both higher and lower.  The panicle's main tip keeps growing even as the side-branches at the bottom of the panicle mature.

 

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This complex show is just beginning.  Act II is even more remarkable. 

 

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By the time the flowers themselves have matured and fallen, the calyx that was the bud-cover for each has matured into a small lavender detail of its own, a Casper-the-Friendly-Ghost little homunculus. 

 

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Most deliciously, the color of the panicle stems changes from a mild burgundy to a shocking violet.  By now, the last few buds at the tip of the panicle are "coming on-line," giving the display yet a third peak of eccentric energy.

 

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Yes, it's quite a wait all Spring and Summer for the shrubby plants to develop buds and flowers.  The burgundy stems are an excellent hint of the color-play to come.

 

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When the buds begin to develop—later in September, in my experience—then the promise of the floral fireworks is nearly at hand.

 

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Here's how to grow this vivid Fall beauty:

 

Latin name

Plectranthus ecklonii

Common name

Cape lilac

Family

Lamiaceae, the Mint family.

What kind of plant is it?

Woody perennial that grows so large it can function as a back-of-the-bed shrub—and grows so fast can do it even as an annual.

Hardiness

Zones 8 to 11.

Habit

Upright but broad as well, thanks to its habit of branching all by itself.  Only somewhat taller than wide.  Shrubby.  The stems are square, and the showy lavender-blue flowers are in terminal panicles that can be ten inches in length.

Rate of growth

Very fast.

Size in one season

Plants propagate readily from cuttings in late Winter or Spring and, with encouraging circumstances–see "Culture" and "How to handle it"—can top six feet by the time they begin flowering that Fall.  To nine feet in a frost-free climate if left unpruned, but because pruning is part of normal handling, that size is rarely reached in cultivation. 

Texture

Full, so leafy and large-scale the plant brings an almost rhododendron-like presence.

Grown for

its flowers: Blue-lavender, in tall panicles of scores of flowers.  The tip of each stem usually produces a panicle, and because plants are naturally bushy, the show is big and even intense.  The floral display has two phases.  Flowers begin to open first near the top of the panicle; the flowers of the lower side-stems of the panicle open later, as do those of the still-developing top tip.  In this first phase, the stems of the panicle are a mild raspberry.  As the panicle matures, most of the flowers drop away, exposing the small starry pale lavender calyces.  The panicle stems now take center stage by turning bright indigo.  The panicles of an entire plant develop in concert, maximizing the fuller but lighter-colored effect of the flowers, and then the lively display of the pale calyces and indigo panicle scaffolding that follows.  

 

its vigor: Plectranthus ecklonii can be propagated from cuttings in Spring, which can mature to full-size blooming "shrubs" by the Fall.

 

its imperviousness to browsers:  As is typical for species in the mint family, Plectranthus is rarely sampled, let alone grazed.

Flowering season

Fall into Spring. 

Color combinations

The lavender, blue, soft raspberry, and indigo of the panicles make Plectranthus ecklonii a natural for plantings that celebrate white, pink, rose, burgundy, and, of course, other shades of blue.  Pale yellow would be swell, too.  To my eye, deep yellow, orange, and red would be a jangle.     

Partner plants

Plectranthus ecklonii is such a big show in itself that it can be used as the sole coloring in planting of neutral greens, or even as a sole individual plant with color amid those neutral neighbors.  Because the flowers combine so easily with pastels, let alone pinks of any saturation and depth, why pass up the chance to harmonize?  The first choices would probably be to add other cool-season plants that also peak via flowers.  Any whose individual flowers are large would be especially welcome: Fall camellias, say, or recurrent shrub roses that have ramped up their flowering thanks to Fall's cooler night.  (If only peonies were in bloom in Fall instead of Spring.  The contrast in flower form and shape, combined with the peony cultivars' infinite options of compatible pinks, roses, and burgundies, would be incomparable.)  Late-season salvias wouldn't provide contrast in scale or flower shape, but could bring additional jolts of pink, purple, and indigo that will shout out to every hue of the flowers of P. ecklonii.

 

The challenge with combining on the basis of floral seasonality, though, is that the whole planting is liable to look like so much green foliage in Spring or Summer.  Better, perhaps, to bring in some colorful foliage and texture that can respond all along to the muted raspberry stems of Plectranthus ecklonii.  If your climate is at once mild enough for the Plectranthus, but cool enough for Japanese maples, the contrast with a purple-leaved Acer palmatum dissectum cultivars, e.g., 'Red Pygmy', and the large shiny green leaves of Plectranthus would be marvelous in Spring and Summer.  But then, Fall:  The Acer is likely to pass into the clashing yellows and oranges of its Fall foliage just as the Plectranthus flowers start showing pink and indigo.  Rats.  Instead, choose Hibiscus acetosella, with purple leaves that are remarkably maple-like, but remain burgundy no matter what the season.  Its rosy hibiscus flowers would work as another of the "large-flowered" contrasters. 

 

I'd experiment also with Euphorbia cotinifolia; the flowers are tiny and white, but the rounded burgundy leaves maintain their color year-round.  Like the Plectranthus, the Euphorbia tolerates only the mildest frosts without dropping its leaves and flowers both. 

 

Other burgundy partners for mild-climate (or container) partnering include any of the darker cultivars of Phormium tenax, as well as Coprosma 'Roy's Red'

Where to use it in your garden

The blue-lavender flowers of Cape lilac are so profuse, and are automatic as long as you've sited the plant in reasonable soil with reasonable water.  But that very generosity can seem almost excessive, or even insistent: Plectranthus eklonii is an all-too-easy temptation in mild climates—like similarly showy and equally bullet-proof Agapanthus and Strelitzia—resulting in gardens that rely too much on flowers and not enough on good design.

 

On the other hand, the show is so big and so uniform—as is the plant itself—that Plectranthus ecklonii can be used for mass plantings in even the largest institutional settings.  Here, too, success is a matter of good design, not in using a lot of an easy-flowering showstopper just because the climate allows.

Culture

Sun or part shade in rich soil and with regular water.  Larger, faster, and bushier in plusher circumstances.  Tolerates full sun as long as the plant isn't drought-stressed.

How to handle it: The Basics

As an annual, plant in Spring, pinching the stems a bit over the Summer to make the plant even bushier than normal, and to keep what can become a sprawling monster somewhat in check.  The plant is so fast-growing that it quickly outgrows even normal-sized planters.  Go right for the large ones: seven- or even ten-gallon isn't too optimistic.  If planted in a too-small container, you'll need to water it twice a day; better to "go big" right from the start.

 

If growing Plectranthus ecklonii in a conservatory (or in the ground in a nearly frost-free climate), where it can flower through the Winter, remove spent flower clusters to encourage further flowering.  If growing it outside where Fall frosts are likely, you'll be lucky to bring it into flower at all, let alone have the opportunity to groom it in preparation for a second crop. 

 

In Spring or whenever the plant has passed its peak, cut all stems down to lowest buds to begin the cycle again.  Expect to renew permanent plantings every few years—which you can do easily, using cuttings from the current planting.

 

If growing in-ground, a group of Plectranthus ecklonii will form a solid mass of growth quickly if planted 30" apart. 

How to handle it: Another option—or two?

Plants grow so quickly in a single season that there's no need to overwinter a containered "specimen" plant to achieve larger size the next.  I myself grew Plectranthus ecklonii this year in a container, and I'm overwintering it just as a stock plant for Spring cuttings.

Any (other) quirks or special cases?

If the ground is moist and the light is dappled, cuttings can be rooted simply by pushing them directly into their permanent locations in the bed. With such ease of handling, Plectranthus should be on the list for every children's garden.

Downsides

Plectranthus ecklonii "works" as an annual outdoors—i.e., comes into bloom before frost—only in climates mild enough that frost isn't expected before late November, or rarely arrives at all.  Where the growing season is shorter, grow the plant in a huge container and bring it into shelter to enjoy the flowers.  Or enjoy the many variegated-foliaged forms of Plectranthus, whose considerable appeal—their foliage and vigor—is independent of their ever-present spikes of modest white flowers; they are exciting from the moment you plant them in Spring, and only become more so as Summer burgeons.

Variants

There are several hundred Plectranthus species, from prostrate and even cascading groundcovers to "biggest coleus you ever saw" perennials that are so fast growing they succeed as annuals, to true giants such as P. eklonii.  No garden should be without a yearly sampler of them.

 

The thick, veiny, gray foliage of Plectranthus argentatus is as elegant as the plant itself is vigorous.  To three feet tall and four feet wide even when grown as an annual.  As is often the case with gray-leaved plants, P. argentatus is very heat-tolerant as long as it isn't unduly stressed by drought.

 

The mint-green leaves of Plectranthus amboinicus are edged in cream.  It's as vigorous and tolerant as P. argentatus, although not as large.

 

The flowers of Plectranthus barbatus are the bluest in the entire genus; this five-foot monster flowers Fall to Spring.  Those of Plectranthus cremnus are blue, as well, and are borne year-round on a plant that's a spreading weed-proof mat of silvery foliage only six inches high.  It's on my wish-list.

 

Plectranthus verticillatus is the classic cascading houseplant known as "Swedish Ivy," which is a misnomer twice over.  The plant is native to South Africa and, being a Plectranthus, isn't an ivy at all: All forms of true ivy are in the genus Hedera.  I crave the bright-foliaged P. verticillatus 'Variegatus'. 

 

Plectranthus ecklonii itself has several cultivars.  The flowers of 'Medley Wood' are distinctly darker than the species; the flowers of 'Tommy' are white, and those of 'Erma' are pink.  'Mona Lavender' is significantly smaller—less than two feet—with lavender flowers.  'Medley Wood' is the one for me.

 

More cultivars and species of Plectranthus graduate from specialist nursery fetish to the mass marketing of garden centers and big-boxes each year.  The Fall- and Winter-flowerers are practical only in subtropical climates, or as conservatory specimens.  The ever-increasing number of forms with variegated foliage are terrific as warm-weather annuals, because their show is based on foliage, not flowers.  (They also tend to flower continuously, but the flowers are usually very small and white, and so are secondary to the foliage.)

 

Availability

On-line and, where hardy, at retailers.

Propagation

By cuttings and ever-opportunistic self-layering: Stems root where they touch—or seem likely to touch, eventually—the ground.  The straight species propagates readily from seed, as well.  Cuttings mature to full-sized plants in under a year.

Native habitat

Plectranthus ecklonii is native to South Africa.  The "Cape" of Cape lilac, then, is the Cape of Good Hope.   

 
 
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