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

 
 

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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.

 
 
 
 

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Allergic to bees? You can still have an exciting garden, full of flowers and color and wildlife.

 
 
 
 

Plant Profiles

Tree Buddleja

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The first flowers of my young tree buddleja!  Individual blooms are so large they look more like flowers of Weigela, and are born on a plant whose thick veiny foliage can be large enough to look more like that of a loquat.  And "tree" buddleja isn't merely somewhat larger overall than the usual butterfly bushes.  The aspirations of Buddleja colvilei are truly arboreal: To twenty feet, with a single stout trunk, too.

 

The green stigma emerges from each bud long before the flowers are open.  Perhaps this is to prevent self-pollination:  The only pollen that could do the job would come from other flowers that have already opened and revealed their four anthers laden with white pollen. 

 

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That the flower buds of this giant species of buddleja resemble dollhouse radishes is just one its charming eccentricities.

 

 

Here's how to grow this unusual Buddleja:

 

Latin Name

Buddleja colvilei 

Common Name

Tree buddleja

Family

Scrophulariaceae, the Scrophularia family?  And that would be?  Another name: the Figwort family?  And that would be?  Finally: The Snapdragon family.

What kind of plant is it?

A small tree, evergreen in Zone 9, semi-evergreen in Zone 8, deciduous in Zone 7b.

Hardiness

Zones 7b - 9.

Habit

Upright and, somewhat unusual for any Buddleja, often single-stemmed, with a short trunk and a broad, mounding, and dense canopy.  Also unusual for a Buddleja, the flower racemes are pendulous instead of projecting.   

Rate of Growth

Medium in my experience growing a containered specimen, but probably faster in Zone 9, where the plant is evergreen and is subject to only mild freezes.

Size in ten years

Size depends on handling and climate.  Slower and shorter in Zones 8 and 7b than in Zone 9.  Potentially, to twenty feet tall and wide.  I'll never forget my first encounter with this species.  Towering over a high brick wall at Kew, it looked more like a giant loquat or, on account of the outward-then-downward arc of the leaves, a monster peach tree.  But no loquat or peach has pendulous racemes of pinkish-red flowers. 

Texture

Even discounting its unusual size, Buddleja colvilei appears to be much weightier than a typical butterfly bush.  The foliage canopy casts dense shade.

Grown for

its non-Buddleja-like qualities: The blooms of its dangling flower clusters are many times larger than the tiny and closely-packed flowers typical of cultivars of B. davidii.  They are more loosely arrayed, too, and on racemes that droop gracefully beneath the foliage; flower racemes of all the usual forms of Buddleja are held fully above surrounding foliage.  Buddleja colvilei is eccentric in its preferred handling, also.  Whereas few Buddleja forms are at their best without drastic pruning—either before flowering (as with B. davidii, B. lindleyana, B. x weyeriana) or after (B. alternifolia, B. globosa, B. salviifolia, and B. yunnanensis)—B. colvilei prefers only minimal pruning, and does not tolerate the routine massacres that are the key to growing handsome specimens of most other forms of Buddleja.  Finally, if the climate and site are sufficiently mild, Buddleia colvilei will grow into a tree, on the scale of a loquat, peach, or American dogwood, with a single trunk and a wide-spreading crown.  Such size and habit could hardly be less related to the multi-stemmed trunk-less growth typical of popular Buddleja varieties.   

 

its large foliage: The fuzzy leaves of B. colvilei can be almost as broad and long as those of rhododendron or loquat, and can be twice as long, even, as leaves of B. davidii cultivars, which are themselves large among Buddleja forms.  The leaves of my young plant are nowhere near full size.

 

its flowers: Pink or reddish bells usually have a white interior, and are dead ringers in size and coloring for those of Weigela.  (The resemblance falters when it comes to petal count:  Flowers of Buddleja have four, whereas flowers of Weigela have five.)  They are sparsely arrayed in attractively relaxed clusters, with their supporting stem fully displayed.  My Buddleja colvilei is still tiny, and its flower clusters are only trial-size: three blossoms at the end of a stem arising from the base of the leaf.  The clusters born by more mature plants can lengthen to eight inches, with several dozen flowers arrayed in five or six tiers.  The flowers of typical butterfly bushes are tiny, and are so numerous and so densely arrayed that they form a tight cone of bloom that completely hides the supporting stem.  The flowers of Buddleja colvilei have only a light fragrance.

Flowering Season

Flowering depends on the climate.  In Zone 9, where the tree would experience little or no Winter stress or die-back, flowering can be in June and July.  In Zone 8 and colder, flowering is usually in late Summer. 

Color Combinations

The mid-green leaves go with everything, but the rose-and-white flowers clearly place Buddleia colvilei in a pink-friendly context.  Because the flowers are bi-color already, additional colors work best when they are solid and in closely-related shades.  Beyond burgundy—which in these circumstances could be seen more as extremely dark rose—contrast from colors other than white, pink, and rose isn't needed.       

Plant Partners

The white-and-rose flowers of Buddleja colvilei would show up well if one or more neighbors had flowers or foliage that were as dark as possible.  Choose from those that also appreciate all possible sun, drainage, and heat, such as Physocarpus opulifolius 'Summer Wine', Cotinus coggygria 'Velvet Cloak', Sedum 'Matrona', Hibiscus acetosella, and, if you're lucky enough to be gardening in Zone 7 and warmer, any of the deep-purple cultivars of Phormium tenax.  Because Buddleja colvilei can grow tree-sized, it casts shade.  All of these burgundy partners need to be planted on its sunniest side. 

 

Plants that feature burgundy and are also more shade-tolerant include Ligularia 'Brit Marie Crawford'.  This perennial requires afternoon shade in anything but near-boggy conditions.  To bring the Buddleja and Ligularia close enough for maximal contrast, the ideal would be for the Buddleja itself to supply the shade the Ligularia needs.  But on account of the dense foliage and wide canopy of Buddleja colvilei, the shade under it is likely to be dry. 

 

To compensate, prepare an unusually rich and moisture-retentive location for the Ligularia—or even create its own bog by excavating a hole large enough to sink a ten-gallon black nursery pot entirely below grade.  Line it with a black "contractor" trash bag and, using a nail, poke a single hole through the bottom of the bag, out through one of the drainage holes in the pot.  The pot will retain water from rainfall or hand-watering, but without the risk of rotting nearby Buddleja roots.  Fill the lined pot with extra-rich soil, mounding up so that the rim is hidden and the Ligularia clump has as much root room as possible.  As you plant the Ligularia, the ultimate kindness would be to use that same nail to poke a single hole in the bottom of a gallon-size plastic milk jug, and "plant" it along with the Ligularia, so its opening is barely above-ground.  It will act as a slow-release reservoir, which you can top up every other day during drought.

 

The round shiny burgundy leaves of the Ligularia provide excellent contrast in shape as well as texture.  If Buddleja colvilei blooms in June and July where you're gardening, there won't be a clash with Brit's deep-yellow daisies, which appear later in Summer.  Buddleja colvilei will almost certainly be the rarer plant and, unlike the Ligularia, is grown primarily for its flowers.  If the two are likely to flower at the same time, disbud the Ligularia.

 

Admittedly, the achievement of such a voluptous Ligularia colony is garnered only by ongoing fussing.  Here are some shade-tolerant partners that also prefer good drainage, appreciate or at least tolerate dry soil, and bring contrast in texture and form, rather than color:  Cephalotaxus harringtonia 'Duke Gardens', Aspidistra elatior, Mahonia bealei, Aucuba japonica, Taxus baccata 'Repandens', Rhodea japonica, Euphorbia robbiae, and all forms of Epimedium, Sarcococca, and Liriope.

Where to use it in your garden

If you're gardening in Zone 8 and warmer, where Buddleja colvilei is reliably hardy, the tree's low spreading canopy and pendulous flower clusters suggest that it shade a small terrace, where you can recline in shelter and enjoy the upward view.  Even better, could the tree also be sited near a shed or cottage whose low roof can nuzzle up into the canopy?

 

In colder climates, Buddleja colvilei must grow in a container, so that in late Fall you can move the shrub into shelter.  The tree prefers to remain evergreen, so can be attractive throughout the Winter.

Culture

Absolutely full sun and well-drained soil.  Buddleja species and cultivars have no interest in shade whatsoever.

How to handle it: The Basics

Buddleja species and cultivars grow fast; there's no need to buy anything but a small starter size.  If growing in-ground, plant in Spring, in any soil as long as drainage is excellent and the exposure to sun is unrelenting.  Because Buddleja colvilei is usually hardy only in the warmest portions of Zone 7 and warmer, drainage and heat are particularly important.

 

Banish the temptation to perform the radical pruning typical of Buddleja.  Instead, let the tree grow free-range, limbing it up gradually if your climate is mild enough (Zone 8 and warmer) for it to form a tree.  After the tree has begun active growth in Spring, you'll be able to identify any leafless stems that were winter-killed.  Prune those off in Spring.  If you need to do formative pruning, do it in Spring also, keeping in mind that any resultant new growth will not flower in the same season.  In Zone 8 and warmer, you can, instead, do any larger-scale pruning after the tree has finished flowering, usually, in July.  There will still be time for resultant new growth to harden sufficiently before Winter.  If flowering is in August or September, it's probably best to delay any pruning that is more than cosmetic until the following Spring, and even then, just prune away winter-killed portions.

How to handle it: Another option—or two!

Colder than Zone 8, Buddleja colvilei is best grown in a container.  In the warmer months, place the container outside where the tree can enjoy full sun.  Water regularly, to encourage generous new growth and the racemes of flowers it produces.  Because you'll be bringing the container into shelter before frost, there's no danger of pruning after flowering even if it occurs into September.  You may well need to prune just to reduce the overall size of the tree's canopy; no matter how big a greenhouse you begin with, eventually space will be at a premium, and especially the warm and sunny spot preferred by B. colvilei.

 

During overwintering, water only when the tree needs it; in cooler greenhouses, and with the shorter days and weaker sun, growth will be slower, or may even stop.  When in doubt, delay watering for a few days, then check the soil surface to feel how dry or damp it is.  Withold water until the soil surface is dry.

 

Because Buddleja colvilei is as hardy as typical camellias and "hardy" palms, you could overwinter the tree in a greenhouse that is only frost-free at night, not one that is truly warm.  In these circumstances, the tree might even drop its leaves, but even if it doesn't, it will probably become dormant.  To minimize the chances of root-rot from excess moisture, let the tree become as dry as possible without causing it to shed leaves from dehydration.  Check regularly to see if the tree is looking too droopy, and could benefit from a little water—or, if lengthening days and strengthening sun in February and March are encouraging it to return to growth, in which case you can increase watering apace.  Bring the tree outside only after there's no further danger of frost, and the weather is reliably warm.

Downsides

Buddleja colvilei is hardy in Zone 7 only with ideal siting; its aversion to pruning makes it a poor candidate for the kind of "extreme overwintering" I enjoy: The species can't be cut to the ground and heavily mulched, or heavily mulched and grown as a die-back, like I do with fruiting fig, Ficus carica.  The growth isn't fast enough or flexible enough to lend itself to espaliers, either.

Variants

The Buddleja genus is positively rife with variants.  There are about 100 species, the majority of which are native to the New World, from the southern US to Chile.  Dozens of other Buddleja species are native to Africa and Asia; none is native to Europe or Australia. 

 

All Buddleja species and cultivars are woody; most are shrubs but there are a few trees in the genus, too.  Evergreen as well as deciduous varieties abound, and the flowers, usually fragrant, can be indigo, blue, purple, pink, yellow, or white.  There are currently no readily-available cultivars with blooms in true red or orange.  The foliage and, as with B. salviifolia, stems of some species and cultivars can be a show in themselves.

 

Buddleja davidii and its endless cultivars are, hands-down, the most popular, with variants from two-foot dwarfs to twelve-foot monsters.  B. davidii is so proficient at self-seeding that some locales have declared it a noxious weed.  Check with the USDA Cooperative Extension Service to find out its status where you garden.  Fortunately, there are now a few sterile cultivars to choose.  B. alternifolia 'Argentea' is unusual in blooming on old wood instead of new, so is pruned after blooming instead of before. 

 

On the list to add to my gardens:  B. lindleyana, which, like B. alternifolia, is so hardy it can be trained as a weeping tree, and B. hemsleyana, which is similar in habit and hardiness to B. lindleyana, but a quarter the size.

Availability

On-line and, rarely, at retailers.

Propagation

By cuttings and by seed.  

Native Habitat

Buddleja colvilei is native to the Himalayas.

 
 
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