A Gardening Journal

Dwarf Osmanthus

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I was so nervous that dwarf osmanthus wouldn't be hardy for me that I planted it behind a hedge of dwarf box for extra shelter in the Winter.  Either the osmanthus is tough already, or the box did the trick: My "dwarf" osmanthus is topping two feet—a giant! 

 

True, true, the dwarf box is certainly not an inspired partner in texture or color.  I was so grateful for the chance to grow 'Nana' osmanthus at all that aesthetics seemed secondary.  At least I thought to put 'Color Guard' yucca in front.  Its huge variegated foliage is a good look; see how it picks up the gold rims of the osmanthus leaves?

 

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Gold rims?  Look closer:  Each leaf has a "hairline" perimeter of gold.  Elegant, eh?

 

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Eight years ago, the 'Nana' osmanthus cowered at the back of the foot-tall box hedge—and now it rests its elbows on it.

 

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If only I had planted a hedge of dwarf variegated box, instead.  For another garden, in another life.

 

 

Here's how to grow this quirky broadleaf evergreen:


Latin Name

Osmanthus heterophyllus 'Nana'

Common Name

Dwarf Osmanthus

Family

Oleaceae, the Olive family.

What kind of plant is it?

Evergreen shrub.

Hardiness

Zones 6 (with some forethought and protection) - 9.

Habit

Dense, mounding, and full to the ground.

Rate of Growth

Slow.

Size in ten years

To three feet tall and 18 inches wide.  Ultimate dimensions are likely to be four feet tall and three feet wide.

Texture

Fine-grained and full.  Internal branching isn't visible.  Much denser than taller cultivars, such as O. heterophylla 'Fastigiata'.

Grown for

its handsome foliage, which is, indeed, so holly-like.  The best way to tell Osmanthus and holly apart is to remember that Osmanthus leaves are opposite, i.e., in pairs, with each leaf directly opposite the other.  Holly —think English holly, Ilex aquifolium—has leaves that alternate up the stems.  Osmanthus : opposite / Ilex aquifolium : alternate.  In Zone 7 and souther, where Osmanthus is quick-growing and easy to establish, it is justifiably popular for evergreen hedges. 

 

'Nana' foliage is typical of a hardy osmanthus, in that it's much smaller (and, therefore, somehow, hardier) than the leaves of the more tender varieties, which can be as big as beech leaves.  It's prickly but not painful.  The edge of the leaf is yellow—truly, the narrowest perimeter line possible—but the effect is not of another color per se, but of unusual visual definition, one leaf from the other.  The leaf veins are lighter green than the body of the leaf, and give additional, if subtle, presence.  "Heterophyllus" means, in this case, that the leaves can vary a whole lot in how spiny and notched they are.  Younger plants tend to be pricklier.  Now you know.

 

its squat and dense habit, which makes the bush appear well-groomed, but without the need for the actual grooming. 

 

its small but sweetly-fragrant flowers that, even better, are surprisingly "out of season," in the Fall.

Flowering season

Fall here in Rhode Island: October, when the last thing one might expect is fresh, sweet fragrance in the garden.

Color combinations

The dark green foliage and white flowers let 'Nana' associate comfortably with all colors.

Partner plants

The rigid and dense habit of 'Nana' can be a strong partner to looser and flexible growth, such as that of ornamental grasses and ferns, provided they're not so close that they could shade out the growth of 'Nana' on the side that faces them. 

 

The yellow leaf-edge is a slender but, therefore, sophisticated opportunity for coloristic play with other plants with showy foliage.  Partners with leaves that are variegated or solid yellow are both possible.  Solid-yellow foliage choices include sun-tolerant 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 Plants page for cultivars whose common names start either with "gold," "yellow," or "variegated."  Over fifty choices and counting.

 

Color from yellow flowers is more ephemeral, and therefore more flexible.  There are daylilies to match that yellow leaf-edge—and also the leaves' green veins.  The sword foliage is a good textural contrast, too.  

 

A scandent partner is another opportunity for added color and texture both, provided that its growth isn't so lengthy or thick that the shrub would look swamped.  Perhaps one of the herbaceous clematis.  They're non-vining, and lean (or flop) instead of twining.  The usual Clematis recta 'Purpurea' is the right coloring all around—white flowers and purple foliage—but it gets much too tall.  Clematis addisonii could be perfect; it grows only a foot or two and its flowers can be rosy on the outside and pale yellow on the inside.  The species is variable; some suppliers show the flowers as blue with a cream interior.  C. reticulata is a small climber with similar potential as well as variability.  Both of these clematis are native to eastern North America, but only rarely seen in gardens here.  (I need to get with the program, too!)  It would be great to encounter them more often.  For more possibilities with native herbaceous clematis, all of whose flowers would associate well with 'Nana', visit the "American Bells" website. 

Where to use it in your garden

'Nana' is a natural front-of-the-bed shrub, because its foliage is full to the ground.  This is a shrub with no bad angle.

Culture

Easy where it's fully hardy.  Full sun to part shade in average to rich soil with good drainage in the Winter.  At the cold end of the hardiness range—the bottom of Zone 7 down into Zone 6—the site needs to be more advantageously sheltered from Winter wind.  Full sun is better up North, 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

 Although 'Nana' is one of the hardiest cultivars, from Zone 7 into Zone 6, any holly osmanthus is somewhat of an achievement, and needs planting (see Culture, above) in focal locations so that you and your garden visitors can be justly proud.  It's a help, as well, to locate the bush fairly near a pathway (but still with helpful shelter of neighboring structures, fences, or evergreens) so everyone can get their noses right up to the flowers, which are so small (again, like holly) that only their powerful fragrance announces their presence from any distance.  Siting near a pathway also helps everyone realize that this isn't, after all, just another upright holly, of which there are a number (i.e., the I. meservae cultivars) that are much hardier, more popular, and, therefore, proportionately less interesting.

 

In Zone 6, it's worth it to spray osmanthus with anti-dessicant the first few Falls, so the shrub looks all the better in May despite the trials of January through March.  On the other hand, by the time the flowers happen in Fall, the shrub will have (here's hoping) long-since recovered from the previous Winter's tip die-back and burned foliage. 

How to handle it: Another option—or two?

The growth of 'Nana' is so dense and regular to begin with, if you added just a snip here and a clip there, the shrub would be a perfect low hedge.  This would have to be all hand-pruning; pruning with power trimmers would multilate the comparatively large leaves more than it would cut them.  A hedge of 'Nana', then, would need to be modest in length, not just in height—perhaps as one of the lesser strands of a knot garden.  

 

You could take even more advantage of the naturally dense growth and modest height of 'Nana' by planting solos of it just at "important" corners or intersections in the knot garden, and training one vertical branch of each bush above the rest to clip it into a diminutive standard.  My knot garden is sheltered by high hedges; I'll try to practice what I preach. 

Downsides

If only 'Nana' were a bit hardier.

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.   

 

O. heterophyllus is the hardiest species, and there's a clutch of desirables even there.  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 must have it.

Availability

On-line.

Propagation

Cuttings and grafting.

Native habitat

Eastern Asia and Southern Japan

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