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

Wild Olive

Despite historically severe winter temperatures, one of the rarest broadleaved evergreens in the garden is thriving. Although native only to mild-winter reaches of southeast North America, devilwood is hardy to Maine. Not just the woody stems, either: the shiny, smooth foliage also.

 

Osmanthus americanus Osmanthus heterophyllus Nana 042318 overall 915

 

The leaves are a puzzle for northern gardeners: Is devilwood some kind of rhododendron? (Not implausible considering the foliage of R. x laetevirens). But it also looks like many broadleaves that aren't at all hardy here—ficus, camellia, and Japanese privet amoung them.

 

Actually, devilwood is a cousin of holly osmanthus. In the picture below, the spiny leaves of one of the many forms that I grow, Osmanthus heterophyllus 'Nana', are just below my little finger. My fingers hold a nearby stem of the devilwood steady. 

 

Osmanthus americanus Osmanthus heterophyllus Nana 042318 915

 

True to its name, Osmanthus americanus is native. It's one of the handy quirks of this species that, though it occurs naturally only from Virginia down to central Florida, then west into Texas, the plants are hardy into coastal Maine. I'm delighted that this one feels quite at home here in Rhode Island.

 

Why "devilwood?" See the "Common name" box below. Why can't you buy this great plant everywhere? See the "Propagation" box. Snap it up when you can. 

 

 

 

Here's how to grow this rare broadleaved evergreen:

 

Latin Name

Osmanthus americanus

Common Name

Wild olive. Also known as devilwood. Why? This source says the wood is dense but susceptible to splitting, making it a devilishly difficult to use in carpentry.

Family

Oleaceae, the Olive family.

What kind of plant is it?

In Climate Zones 5 and 6, an evergreen shrub. In Zones 7 to 9, an evergreen tree.

Hardiness

Zones 5 - 9.

Habit

Loose and irregular when young, but gracefully branched and full with maturity. Osmanthus americanus responds readily to pruning, so trained specimens can be strikingly compact as well as dense.

Rate of Growth

Slow even where fully hardy, in Zones 7 to 9.

Size in ten years

Ultimate size seems to be very much influenced by the mildness of the climate. In Florida, Osmanthus americanus can become fifty feet high, but averages "just" ten to twenty feet high with a spread of ten to fifteen feet. Even there, the tree is described as slow growing.

 

My thriving youngster might barely top six feet by the close of its first decade. My specimen is about five feet tall and was planted four years ago, at which time it was likely already a couple of years old. I doubt it will ever top twelve. This ultimate shortness might be a consequence of the species' slow growth in general, exacerbated by a further slowing of growth in Zone 6's comparatively shorter growing season and relatively cooler temperatures winter as well as summer. The cooler climate limits ultimate height no matter how many years pass. 

Texture

Loose when growing free-range. Dense, even rigidly so, when pruned. This might be just the look you'd want when growing Osmanthus americanus as a hedge. See the second "How to" box, below.

Grown for

its evergreen foliage. In contrast to the prickly leaves of the aptly-named holly osmanthus (Osmanthus heterophyllus) that is the only other osmanthus reliably hardy in Zone 6, the leaves of O. americanus are smoothed-edged. They look much like broadleaved evergreens not at all hardy in Zone 6, such as the ficus (F. benjamina) sold by the millions as a tender indoor foliage tree, Japanese privet (Ligustrum japonicum), or almost any camellia (Camellia japonica and its numerous hybrids). So the surprise with devilwood is threefold: that this broadleaved evergreen is hardy, that it therefore isn't a ficus, privet, or camellia, and that it's a rarely-seen species of osmanthus.

 

its highly fragrant white flowers, whose combination of penetrating sweet scent with relatively small size is typical for those of woody plants that flower in late winter or early spring. The flowerbuds are reported as being prominent by early winter, so are a welcome portender of the floral display to come.  

 

its hardiness: No other osmanthus is hardy to Zone 5; the ever-popular O. heterophyllus cultivars are hardy to Zone 6 at the coldest but, with the exception of 'Goshiki', which seems particularly tough, can be challenging to establish in climates colder than Zone 7.  

 

its rarity: Although broadly native in the American southeast, devilwood is seen all too infrequently in gardens, even where hardy. One reason could be the reported difficulties of propagation, which see, below.

 

its tolerance of soil moisture: broadleaved evergreens for soil that is even transitorily wet are few and far between. (Can you think of even one other than Ilex glabra?)

 

its shade tolerance, which is reported to be the best of any osmanthus. 

Flowering season

Early spring or even late winter, which is a surprise in Zone 6 in general, but even more of a surprise for those familiar with the only other osmanthus that's at all hardy in Zone 6, the fall-flowering Osmanthus heterophyllus. My young devilwood isn't mature enough to flower; this might be simply be a matter of young age or comparatively small size—barely five feet high, and with still slender growth at that—or a combination of both. 

Color combinations

Its dark green foliage and white flowers let Osmanthus americanus associate comfortably with all colors.

Partner plants

Devilwood's white flowers are striking in their fragrance and, especially here in New England, the tree is also thrilling on account of its extreme rarity. But if considered strictly for visuals when not in flower, devilwood's shiny, smooth leaves and, with maturity, full canopy but unremarkable habit overall, say "background filler." Combine this with the species' shade tolerance, and you have a congenial dark-leaved evergreen to associate with all kinds of showier near neighbors.

 

The loose habit provides easy access for vining or scandent plants whose ornamental thrills would be better displayed when lifted higher off the ground and set against a classy green backdrop. I have planted nearby a rare variegated winter jasmine, Jasminum nudiflorum 'Aureum', and could easily swag a couple of its long willowy stems through the devilwood's branches. Winter jasmine is normally a monster that can swamp parked cars and outbuildings, but this variegate is almost tentative at extending just six feet or so. Clematis or roses that also don't grow too large are other options.

 

Foreground partners with colorful foliage that's either season-long or year-round would be excellent. Solid-yellow foliage choices include yellow hostas, 'All Gold' hakonechloa, 'Pee Dee Ingot' liriope, 'White Gold' spirea, and the compact bald cypress, Taxodium distichum 'Peve Yellow'. Trim the latter to keep it dwarf enough. For more choices, look on the More Plants to Try page for cultivars whose common names start either with "gold," "yellow," or "variegated." There are over fifty choices and counting.

 

I wish that Lonicera nitida 'Baggeson's Gold' were hardier in my in not-quite Zone 7 garden. Its minute gold leaves are arrayed with nearly ferny density on arching branches, and would provide a stunning contrast. It dies back to the base during a severe winter (such as this past one) and, so, will never reach the height and bulk needed to pair with devilwood.

 

Because devilwood is shade-tolerant as well as evergreen, it could be an understory to larger deciduous plants with cool-weather performances to enhance. There's particular potential in Zone 6, where devilwood isn't likely to grow taller than eight to ten feet. (In warmer climates, it can grow several times as large, so could only understory high shade trees). There are scores of possibilities amoung Acer, CornusFraxinus, Hamamelis, Parrotia, and Styphnolobium to savor.

 

When used as a hedge, devilwood could backdrop anything a hedge of yew or holly could. 

Where to use it in your garden

In Nature, Osmanthus americanus is often found in shady spots near fresh water, and is a natural candidate for such habitat in gardens, too. That said, excess soil moisture usually compromises hardiness, so at the cold end of this species' hardiness—Zones 5 and 6—success is likely to depend on decent to excellent drainage. Consider Osmanthus americanus for wetland use only in Zone 7 and warmer.

 

In Zones 5 and 6, devilwood is likely to be a "What is it?" mystery, and should be sited prominently lest curious visitors trudge deep into beds to puzzle over its identify. It's a help, as well, to locate the bush fairly near a pathway so everyone can get their noses right up to the flowers. Although their penetrating fragrance announces their presence from any distance, you'll want to appreciate that all of that scent comes from surprisingly small blossoms.

 

In Zone 7 and warmer, this evergreen shrub would make a great evergreen backdrop, or a filler for difficult damp and shady locations. Anywhere it's fully hardy, it could make a fantastic hedge if planted in sunny locations, which encourage dense growth, as well as a quick response to pruning.

 

Devilwood foliage can be a target for browsers, so don't plant it in locations that don't offer protection. The plant will eventualy grow too large to be sprayed with, say Ropel; it will also get too large to protect with a seasonal deer-proof barrier, such as mesh or snow-fence. Better to site devilwood in an enclosed garden, or plant it in semi-shady urban gardens, where browsers aren't an issue.

Culture

Easy where it's fully hardy: Zones 7 through 9. There, devilwood thrives in full sun to shade in average to rich soil that doesn't become dry enough to subject the plant to drought stress. Unusually for any evergreen, broadleaved or coniferous, devilwood tolerates soil that is sometimes saturated or even submerged by seasonal flooding, so it's a godsend for shady, low spots that might otherwise lack for any evergreen presence.

 

In Zones 5 and 6, by contrast, decent to excellent drainage will likely enhance hardiness and, therefore, the likelihood of success. I'll never forget my first encounter with an older devilwood, at the Arnold Arboretum near Boston, during a grim winter where the snow had become literally knee-deep. The location was on a hillside, so had fantastic drainage; the devilwood's foliage was unscathed by the relentless Zone 6 cold.

 

Full sun is better in Zones 5 and 6, too, which helps each season's growth to ripen as much as possible in summer and fall, which, in turn, helps it better withstand the stresses of the coming winter. Larger individuals are hardier than youngsters, so buy the biggest you can.

How to handle it: The Basics

In Zone 6, plant Osmanthus americanus only in spring. In Zone 7 and warmer, you could plant at almost any time, spring into fall, that the tree is available. In Zone 6, it's worth it to spray the young tree with anti-dessicant the first few falls, to minimize any delays in maturation that might be caused by recovery from regular bouts of winterkill.

 

This kindness helps the devilwood increase in size as well as speed toward the onset of flowering, neither of which seem very eager in my experience. Anti-dessicant may be a cosmetic preference even after flowering is regular: The flowers will appear long before new foliage is formed, and any winter-damaged foliage would detract from them. Note, though, that I have not used antidessicant for my devilwood, even in these last two harsh winters, and there has been almost no winter-damaged foliage. But there still aren't any flowers, either. Flower buds form in late fall, before damaging winter weather has arrived. In years to come, I'll experiment whether those buds would benefit from the protection of antidessicant to survive until early spring, and post the results.

 

If using devilwood as a natural-growth screen or filler, formative or maintenance pruning isn't needed. In my experience, the foliage and, therefore, the branches can be weighted down dramatically by heavy snow. This hasn't caused damage yet, but likely slows the increase in height—hence the staking I've provided to the central stem of my youngster.

How to handle it: Another option—or two?

Devilwood's enthusiastic response to pruning suggests that it can be formed into a hedge. Space plants three feet apart, clipping off the tips of the tallest stems in early spring for the first couple of years to encourage bushier growth below. Eventually, you'll want to control width by cutting the tips of side branches in early spring as well.

 

After some years, you may need to reduce width and height dramatically by cutting into older woody stems. Not to worry: Devilwood responds readily even to radical pruning. Do it in early spring, so that the hedge has the longest possible portion of the growing season to sprout new growth, then mature it enough to be hardy during the coming winter.

 

Devilwood hedges won't flower as much as free-range plants, because the annual pruning often removes much of the growth that is mature enough to form buds. It would be a worthy experiment to prune devilwood right after flowering is completed—in mid to late spring, in other words—to see if the resultant new sprouts have time to form buds in the fall. If not, the next experiment would be to prune only every other year, or even every third year, if that's how long it takes for resultant new growth to mature to flowering age. The trade-off of a year or two of shaggier hedge could be counterbalanced by the unusually heavy production of flowers: Depending on how much growth is removed, the pruning could encourage a crop of new stems that is much more profuse than would have arisen from normal free-range increase—and, being roughly the same age, those new stems would all come into floral maturity the same season.

Quirks and special cases

Osmanthus americanus gets its other common name, wild olive, from its hard, dark bluish purple fruits that, at about a half inch across, are dead-ringers for the fruits of its true-olive namesake and cousin, Olea europaea. They are not edible by humans, although birds relish them.

Downsides

Osmanthus americanus is reported as being difficult to propagate, whether by cutting or by seed, making it a challenging plant for growers to offer. It would be great to use devilwood as a hedge—but, likely, maddening to try to locate enough plants.

 

I've learned the hard way that foliage of the other osmanthus hardy in Zone 6—O. heterophyllus—is likely to be unpalatable to deer because it is spiny, not because it tastes yucky. At any rate, the unarmed leaves of O. americanus can be completely devoured. Devilwood needs protection from browsers.

Variants

Ah, the osmanthus. So many to yearn for, not least because so many species aren't hardy at all below Zone 7. South of the Potomac River, osmanthus are increasingly popular, i.e., not "Uncommon & Astonishing" at all. But east of the Hudson River? Notable, indeed. To my knowledge, Osmanthus americanus and O. heterophyllus are the only two that could possibly be established.   

 

Osmanthus americanus is the hardiest by far, with success reported even in Zone 5; there can never be too many hardy broadleaved evergreens in Zone 6 and colder, so the species is desirable on that basis alone. (Plus, there are its fragrant flowers.) A softly variegated form is sometimes available at this peerless nursery.

 

O. heterophyllus is the second hardiest species, and there's a clutch of desirable forms. Far as I can tell, 'Ogon' is the same as 'Aureus'; ogon is Japanese for gold. The young foliage of 'Purpureus' is so dark and shiny it seems dipped in tar; I'm still trying to establish it. 'Gulftide' is green-leaved but reputedly hardier than the species; you can't prove it by me, though. 'Goshiki' has strongly variegated foliage, and seems substantially hardier than other cultivars. 'Fastigiata' is loose and upright; it and 'Nana' both seem fully hardy in Zone 6. 'Sasaba' has small, deeply-incised green leaves that, unlike the rest of the "holly" osmanthus, are armed with spines so rigid and sharp they are guaranteed to draw blood. Of course, I had to have it. I have succeeded in establishing all of these but Ogon.

Availability

On-line and at specialty nurseries, but often only rarely.

Propagation

By both cuttings and seeds but, says this source, difficult either way. Says this source, seeds need to be handled as soon as they are ripe, and usually take two years to germinate: You are never likely to be able to buy devilwood seeds, then, and could obtain them only through direct harvesting from fruiting trees.

Native habitat

Despite its hardiness into Climate Zone 5, Osmanthus americanus is native only to Zones 8 and 9, in the southeastern United States from coastal Virginia south to central Florida and west to Texas, as well as in Mexico. 

 
 
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