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Plant Profiles

Dwarf American Holly

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Yes, this is American holly, but it's the cultivar that's afraid of heights.  Unlike the species, 'Maryland Dwarf' isn't a tree at all, but a prostrate shrub that only gradually—reluctantly—mounds upward to three to five feet tall at the highest.  This young plant is being bested in upward aspirations by—of all things—the dwarf boxwoods to the left, even though that shrub is legendary for its resolutely and permanently tiny stature. 

 

At any height—or lack of—deer ignore American holly.  So count on this ground-hugging shrub to stay green and leafy regardless of how many critters roam your garden.

 

 

Here's how to grow this rare mounding American holly:


Latin Name

Ilex opaca 'Maryland Dwarf'

Common Name

Dwarf American Holly

Family

Aquifoliaceae, literally, the "wet leaf" family, from Ilex aquifolium, English holly, whose leaves are so glossy they do, in fact, seem to be wet.

What kind of plant is it?

Broadleaved evergreen tree.

Hardiness

Zones 5 - 9.

Habit

Mounding, multi-branched, full to the ground; without a central trunk.

Rate of Growth

Slow to medium.

Size in ten years

Two to three feet tall and wide.  Potentially to five feet tall and six to eight feet wide.

Texture

Dense and full.  American holly is a rigid plant at any size and age; the branches are almost motionless even in strong wind.

Grown for

its rarity: By one count, American holly cultivars have topped a thousand.  'Maryland Dwarf' is one of the few dwarf cultivars among them.

 

its habit, which combines classic American holly foliage with a prostrate and only gradually-mounding habit more typical of cotoneaster.  As shrubs mature, their numerous stiff branches, mounding habit, and (eventually) dense coverage by spiny foliage make them ideal shelter for small animals.

 

its lack of appeal for deer, who eschew the stiff and prickly foliage, which would be painful to eat. 

Flowering season

Early Summer: May in Rhode Island.  Holly flowers are small and white, and not really showy.  'Maryland Dwarf' is a female, but blooms and therefore berries only sparsely.  Grow this holly for its habit, not its fruit.

Color combinations

Dwarf american holly goes with any colors.

Partner plants

'Maryland Dwarf' looks best when it grows full to the ground, so keep surrounding horticulture from casting any more than minimal shade.  Surround with very low spreading groundcovers—Lysimachia nummularia 'Aurea', say—that can creep outward as needed as the holly shades their inner reaches.  Yes, you may well need to pluck out the occasional Lysimachia shoot that is able to climb up into the holly. 

Where to use it in your garden

'Maryland Dwarf' is too dense and full to the ground to use anywhere but at the front of a bed.  Growth can be regular enough—especially with a bit of pruning—that the bush could be planted regularly down the front of a long border, or at the corners of a terrace or a rectangular bed.

Culture

Full sun to part shade, any reasonable soil.  Faster in full sun and rich well-draining soil.

How to handle it

American holly is often a part-shade understory tree where it's native, but the growth is so much denser in full sun that this is normally the choice for use in landscapes.  This is especially the case with 'Maryland Dwarf', which is open and irregular in youth.  Pinch the very tips of the young branches to help it branch out more, and therefore grow even denser.  

 

Hollies handle Winter better and better as they get larger, but because 'Maryland Dwarf' is slow-growing as well as rare, you're not likely to be able to start with more than a youngster a foot or two tall.  American hollies in general succeed well north of New York City, but appreciate your thoughtfulness in siting and care.  Plant small-sized individuals only in the Spring in Zones 6 and 5; larger-sized plants can be installed in the Fall, too.

 

"Full sun" doesn't mean being exposed to all possible Winter blasts.  Can there be large evergreens to the north?  Your house to the east?  Good winter drainage, as ever, is very helpful to hardiness, especially for any plant with evergreen leaves.  A thick but loose Fall mulching with leaves and shredded bark is also a good idea.  In Zone 5, spray with antidessicant the first few Falls. 

How to handle it: Another option—or two!

Although 'Maryland Dwarf' is slow-growing, and will always be a fraction the height of the straight species, it can become twice as wide as tall.  The plant is always dwarf in height, then, but with a mature spread of six to eight feet, it's not really a dwarf in width. 

 

So allow room if you want a full-size plant, or prune the tips of the perimeter branches to produce a dome whose width is only as wide as its height.  Prune in early Spring (which provides the maximum length of warm weather for the resultant new growth to mature and harden in advance of Winter) or in mid- to late-Fall (by which time the weather will have become so chilly that new growth won't resume until Spring).  Don't prune in Summer or early Fall, because the resultant new growth won't have time to hardy sufficiently to withstand the imminent Winter.

 

Hollies all respond easily to pruning, producing side shoots that thicken the growth of the plant much faster than if it were left to grow free-range.  If you are attentive with an annual early-Spring pruning 'Maryland Dwarf' as well as second round (which would be much less intense than the first; just pinch off any tips that are relatively out of bounds), you can shape 'Maryland Dwarf' into a tightly-foliaged dome.  It will be a celebration of uncompromising geometric fidelity—or, depending on your taste, a weird artifice that's a desecration of the plant's natural form.

 

You could create the ultimate geometric triumph—or weird desecration—by grafting 'Maryland Dwarf' to the top of a young tree of the straight species Ilex opaca.  Graft at four or five feet high.  Taking care that the branches from the trunk don't overgrow the slower 'Maryland Dwarf' grafted at the top, let all the branches, grafted or not, grow for a few years.  This will help thicken the trunk and pump up the 'Maryland Dwarf' all the faster.  The next Spring, cut off all the branches from the trunk, and keep any resultant shoots pruned promptly.  Gently pinch and prune the top canopy of 'Maryland Dwarf' in early Spring, to help it form a tight sphere of foliage.  After several more years, you'll have an impressive standard of American holly six or seven feet tall, with a dense head of foliage three or four feet across.     

Downsides

Hollies can be troubled by all kinds of pests and diseases, but strong-growing plants are much less susceptible.  Check with local nurseries as well as your local USDA Extention Office to see what American holly cultivars they recommend for your locale.

 

The branches of 'Maryland Dwarf' are startingly brittle, and can snap at the base if you bend them.  Prune the shrub gently and, as you weed among the still-open branches of young plants, take care not to disturb them in your zeal to reach every sprout and sprig.  Instead, reach weeds as best you can from between extant gaps in the foliage, instead of attempting to more branches to create temporary openings that would provide, fleetingly, more direct access.  Despite this fragility, the branches don't seem to snap from snow-load. 

Variants

There are about a thousand cultivars just of Ilex opaca, plus many hundreds more of the dozens of other holly species.  They vary in berry size, profusion, and color; leaf size, color, degree of glossiness, and spinyness; hardiness; and habit, which can be upright, wider, dwarfer, or denser.  Hollies of all kinds accept pruning easily, so in addition to free-standing, free-range growth, you can have terrific hedges of them.  Why don't I ever hear of espaliered holly?

 

But the overall look of American holly is similar enough, cultivar to cultivar, that this isn't the plant to collect extensively for regular garden usage.  Have a happy free-range specimen American holly, or a grove of the same cultivar; have a dwarf (such as 'Maryland Dwarf' or the similar 'Clarendon Spreading'); have a hedge; have 'Stewart's Silver Crown'—and you're about done.  Unless you're an arboretum or a holly fanatic, you're not likely to have more than a very few different American hollies.  So instead of the straight species, choose only among the cultivars that are of particular merit for your locale.

 

Oh yes:  Nearly all hollies are separately-sexed.  Unless you live where American hollies are occuring naturally in the woods, you probably need to plant a male American holly so your females get a respectable berry crop.  All the more reason, then, to plant a grove of free-range American hollies, with the lone male discreetly and respectfully at the back.  There's variety among the male hollies as well; see which are recommended for your locale.  The male doesn't have to be anything the size of the females at planting, and one male can handle a harem of females, too.  So while you need a different male for each species (and, sometimes, even each cultivar) of holly you plant, you'll only need one male American holly.  It's fine to start with a small-sized male plant, especially if that means that it's a better cultivar.

Availability

On-line.

Propagation

By cuttings that are started in the Fall.

Native habitat

Ilex opaca is native to the southeastern United States, from eastern Texas to northern Florida to New Jersey.

 
 
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