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Plant Profiles

The Best Season Ever: Himalayan Mint Shrub



It was the first of October, and my Colquhounia had just begun to flower.  The shrub was young, too, so these were its first flowers ever.  And it was also my first experience of this species, finally doing what it does best: providing red-and-yellow flowers—in Fall!—on a critter-proof shrub that loves heat and sun.  So far, so good.




My overall handling of the shrub, though, was amateur-night-in-Dixie.  The species isn't hardy here, so I kept it in a pot.  But growth was so quick that the pot dried out daily by August.


Next year, I'll do better by this unusual species.  I'll even follow my own advice in "Culture" and "Handling," below.



Here's how to grow this rarely-seen mint relative:


Latin name

Colquhounia coccinea.  The genus is pronounced "co-HOON-nee-uh."

Common name

Himalayan mint shrub


Lamiaceae, the Mint family.

What kind of plant is it

Evergreen shrub that, at the colder end of its hardiness range, can become deciduous and, at the coldest end, herbaceous and resprouting from the base.


Zones 8 to 9.


Multi-stemmed almost from the base, like a Buddleja.  Upright, usually taller than wide.  

Rate of growth

Fast when happy.

Size in ten years

Colquhounia is normally pruned back severely in Spring, so the free-range size isn't relevant in the garden.  In climates with only mild frosts, unpruned individuals can become six to ten feet tall, and as wide.  With Spring pruning, the shrub could still be four to six feet tall and wide by the time it begins flowering in late Summer. 


Fuzzy and loose; the overall habit has a similar gawkiness to that of Buddleia davidii.

Grown for

its eccentricity: It's tempting to grow Colquhounia just to pronounce it, let alone because, while the shrub's foliage, woody habit, and scale suggest that it's a Buddleja, Colquhounia is actually in the mint family.  The two groups of plants are cousins, botanically—both are in the Lamiales order—but it's still a frisson in terms of our garden experience of mints as spreading herbaceous perennials, with white or pinkish flowers, that look and behave nothing like a stiffly-stemmed shrubby Buddleja, nor the stiffly-stemmed shrubby Colquhounia.  


its flowers: narrow trumpets can be anything from pink to orange to red; a yellow throat is the one constant.  They are arrayed in crowded short racemes at the tips of stems, with smaller clusters emerging from the leaf axils below.


its late-Summer flowering, which brings a jolt of color and enthusiasm to gardens that might otherwise be looking tired.


its imperviousness to browsers:  As is typical for species in the mint family, Colquhounia flowers and foliage are not at risk.

Flowering season

Late Summer into Fall. 

Color combinations

The pale felty foliage goes with everything, but the red-and-yellow flowers—which read as orange unless you're appreciating them directly—most definitely do not.  Site Colquhounia amid neighbors that are also thumping for yellow, orange, and red, or cooling things down with burgundy or dark green.  Avoid pink, rose, or blue, and consider white only if the larger context is also clearly introducing it: Although, technically, white can mix with everything, it brings only a chilly diplomatic cordiality to the yellow-red-apricot-orange liveliness of the flowers of Colquhounia.  See "Partner plants," below. 

Partner plants

The flowers of Colquhounia are multi-colored—variegated is a fair description—so neighbors with variegated foliage of even congenial colors are likely to look hectic.  The felted stems and foliage of Himalayan mint shrub is another interesting-enough-already feature that also augers for partner plants with simplicity of form and coloring.  But "simple" doesn't mean dull or bland.  If you're gardening in Zone 8, Colquhounia and purple-leaved forms of Phormium tenax are both quite hardy; both thrive in good drainage, full sun, and all possible heat.  Other purple-leaved partners hardy in Zones 8 and 9 include Cordyline australis 'Purpurea' and Cotinus coggygria 'Velvet Cloak'.  Coppice the Cotinus so that it doesn't produce dusky-pink flowers, which would clash spectacularly with those of ColquhouniaEuphorbia cotinifolia and Hibiscus acetosella also supply heat-loving burgundy foliage, but can only be grown as permant in-ground partners in Zone 9.  Colder than that, both thrive in Summer containers.


Partner plants whose main calling card is their flowers work best when the flowers are in solid colors, and have distinctly different shapes than those of Colquhounia.  Avoid the repetition of tubular and trumpet-shaped flowers, so no nearby Aloe, Buddleja, Jasminum, Kniphofia, Leonotus, Salvia, or Tecomaria, please.  No Campsis radicans, either; the flowers of Campsis grandiflora 'Morning Calm', however, would be glorious, being of identical coloring but extraordinarily broad and flaring shape, and dramatically larger size. 


Instead, consider orange and apricot forms of Canna, Dahlia, and Hedychium, whose flowers are on a much bigger scale, and also will be peaking in late Summer and early Fall.  


Colquhounia could also be part of a more xeric context, where its grey foliage and hot flowers would mix with succulents as well as members of the woody lilies: Agave, Nolina, and Yucca.


Because the habit of Colquhounia tends toward bare ankles, or even bare shins, the shrub benefits from being sited in back of broad plants whose habit is full to the ground, and whose contour is mounding and dense instead of upright and spiky.  Foliage that is non-felted or even shiny would be a help, too, as would be a notably darker color.  Buxus and Ilex crenata have just such dense mounding forms, and thrive in Zone 8 and 9.  Forms of Pittosporum tobira are appropriate, too, especially because, like Colquhounia, this species isn't hardy colder than Zone 8.  In a xeric context, consider fronting with a colony of one of the spreading forms of Opuntia, such as O. basilaris.  

Where to use it in your garden

With its tendency to bare shins, Colquhounia welcomes being sited farther back in a bed.  This sun- and heat-lover needs all the advantages you can provide to maximize the warm and mild conditions it prefers.  See "Culture" and "How to handle it," below.


I'm going to use Colquhounia in my red garden, where any plant with hot coloring that doesn't interest a groundhog is at a premium.  Thank goodness for the shrub's minty heritage.  I'll be growing it is as a "Summer sunk" container plant; see "Quirks" below.


Full sun in almost any well-draining soil.  As usual, excellent drainage enhances hardiness.  The shrub appreciates being sited with walls to the north or east, to reduce cold wind and also maximize the effect of hot afternoon sun and, after sunset, radiated stored heat.  If those walls are masonry, so much the better at night: They'll have absorbed all the more heat during the day. 

How to handle it: The Basics

In Zone 8 and warmer, where the shrub is solidly hardy, plant in Spring, and water just until established.  The shrub appreciates good drainage and light, loose soil more than attentive watering. 


Handle year-to-year as you would Buddleja davidii, by leaving stems intact through the Winter and waiting in Spring until leaf-buds begin to swell and reveal new foliage before cutting back to just above the lowest of them.  Colquhounia is slow to flower, at least here in New England, but if you wanted to keep the shrub lower, and to encourage even more heads of bloom, pinch off the tips of the young stems in mid-Spring, when they have only a few pairs of leaves.  You'll double or even quadruple the number of stems that will be producing flowers by Fall. 

How to handle it: Another option—or two?

If attempting establishment in Zone 7, siting with impeccable Winter drainage is essential.  Plant on a slope, no matter how slight.  Siting to the west or south of a masonry wall would be the next imperative.  Leave stems up through the Winter, but mound over the base of the shrub with sand to the depth of six inches or even more.  in Spring, scuffle the sand back with your fingers, trying not to damage any leaf-buds that might be becoming active.  Wait until new growth is clearly in evidence before cutting the old stems back to the lowest active leaf-buds.

Any (other) quirks or special cases?

Colder than Zone 7, Colquhounia is too fast growing to be attempted in anything but a very large container for Summer-long success.  But that container would be so large that it would be difficult to drag the shrub into shelter in Fall.  Instead, grow Colquhounia in a medium-sized nursery pot—5 gallon, say—which you sink directly into a hot-and-sunny location in the garden, or into a much larger (10 gallon at a minimum) container for the Summer. 


After light frosts have convinced the shrub to contemplate dormancy, cut all stems back by half to make the nursery pot more easily accessible.  Then plunge a shovel vertically all around the outside of the nursery pot to sever roots that have grown out of its drainage holes, and lift the potted shrub for overwintering in shelter.  Keep in cool frost-free light, watering little or not at all, so the shrub stays dormant but expectant of Spring's return.  I don't have experience overwintering Colquhounia in frost-free darkness, but that has worked with tender Buddleja species I grow (B. nivea and B. salvifolia), so is worth a try.


If you have the space, bring the shrub into stronger light and greater heat in late Winter, to encourage resumption of growth.  Only then should you prune the stems down to their lowest active leaf-buds.  If growth is unexpectedly vigorous, you can pinch the stems to control size and encourage still more branching. 


Return the shrub to its Summer location only after Spring has reliably warmed up.


If only Colquhounia were a zone hardier.  An enduring and enthusiastic colony would probably be an achievement north of Philadelphia.


The stems and leaf-backs of Colquhounia coccinea var. mollis are covered in dense rust-colored hairs.  The hairs of Colquhounia coccinea var. coccinea are more sparse, and the look is silvery instead of rusty.  In actuality, the difference is minor—or there's plenty of confusion in identifying which plant is which. 





By cuttings and by seed.

Native habitat

Colquhounia coccinea is native to Nepal, and is named after a Scot, Sir Robert Colquhoun, who lived in Nepal in the 19th Century and was, reportedly, a patron of the Calcutta Botanic Garden.  The shrub is reported as having been cultivated in Great Britain by 1850.  In North America, Colquhoun has come to be spelled Calhoun 

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