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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

The Best Season Ever: Bamboo Muhly Grass

Eucomis pole evansii Hemerocallis Princess Irene Muhlenbergia dumosa 091415 640 

 

This year, my version of a "red" garden has continued to mellow. Yes, there are still flashes of hot colors but, really, everything else that could plausibly go with them is welcomed en masse. In the picture above, mango flowers of 'Princess Irene' daylily emerge over a longer period than any other: August into October. At their back, the thick spikes of creamy flowers are those of the tallest, latest pineapple lily, Eucomis pallidiflora ssp. pole-evansii. The centers of its flowers are just able to call out to the mango daylilies.  

 

At their back, the most graceful ornamental grass ever, Muhlenbergia dumosa. Bamboo muhly grass brings motion and can't-be-topped featheriness to all Summer gardens, "red" included, because it doesn't produce its sometimes-pink flowers until Winter.  

 

Muhlenbergia dumosa fingers 100315 640

 

The "bamboo" part is apt: Stems of this grass may be slender, but they are wiry verging on woody. And few classic ornamental grasses bear stems that form side stems, whereas many bamboos do. I first acquired clumps of this plant as filler for Summer containers for a client. And the whatever-they-were grassy things looked so spectacular when I returned to remove the containers in October that I couldn't resist potting up them up in hopes they'd overwinter.

 

But by February, my "bamboo" was in full bloom. Bad news! Many bamboos die after flowering (to regenerate from seed), so I was at first bummed that all my effort to preserve these beautiful "bamboos" were for nought: Maybe I'd have just a few seedlings for Summer, not the bigger-than-ever clumps I wanted.

 

Muhlenbergia dumosa fingers in flowers 022815 closer 640

 

A bamboo expert patiently explained that, no, this wasn't a bamboo at all. It's a cool ornamental grass, Muhlenbergia dumosa, that would thrive in a container for many years. Flowering in Winter was normal, not fatal.

 

So far, so good. The pair of clumps I had potted up finished flowering by Spring. Stems die after they flower so, before setting the pots out in the garden for the Summer, I clipped each dead stem off at ground level. By Summer, they were replaced by a lush fountain of new growth.

 

Muhlenbergia dumosa 100315 640

 

Muhlenbergia dumosa isn't hardy colder than Zone 7 and, even so, demands perfect drainage to overwinter. My garden has level terrain and deep heavy soil, so bamboo muhly grass would grow best when kept in a pot. I sunk each clump, black nursery pot and all, into a large terracotta tub of 'Black Knight' cannas. They have purple-edged leaves and—this being the red garden—flowers that were saturated scarlet.

 

Next season, I'll treat bamboo muhly grass as a soloist. Although it is easy to pair this grass with contrastingly large-leaved partners, it doesn't need those companion plants to be in the same pot. See "Partner plants," below, for possibilities.

 

The stems (narrow, long, and wiry) and foliage (narrow and long) of this grass synergize to create its fluffy, voluminous, and often cascading growth habit.  

 

Muhlenbergia dumosa full stem 100715 640

 

Stems can be four to six feet long, and only bear foliage at their top half. The slender leaves aren't born along the main stem nor, even, on the many lengthy side stems. Rather, still smaller stems emerge from the side stems, and they are the ones that bear the leaves (and, in Winter, the flowers).

 

 Muhlenbergia dumosa side stem 100715 640

 

The total weight of these tiny leaves might be just a few grams per stem. And while the stems that bear them are skinny—lightweight, in other words—they are strong; a given stem of bamboo muhly grass isn't going to weep because its foliage and upper stems are too heavy to be held erect. And yet, the group of stems of bamboo muhly grass that make up a clump invariably form a billowing and often weeping cloud.  

 

What gives? Because stems are so light, and bear enough foliage (thread-thin though each leaf is) to create at least some wind resistance, they catch even gentle breezes. These nudge each stem out of alignment and, because of all of its projecting side stems and the stem's overall lightness, there isn't enough pull created by the outward flex of the wiry stem for it to spring back and muscle it's way into the center of the colony to regain its upright position. Day after day, then, the upper portion of each stem is being blown to the outside of the clump even as it remains tethered to the base of the colony by the stem's strong and wiry bottom portion. And each time, the stem can't return to the interior. Plus, new stems keep emerging; they are more or less erect as they lengthen, so add to the central barrier that prevents the return of older stems that breezes have been keeping at the clump's periphery.

 

The clump's overall weeping billow, then, is more the result of what happens to the stems—being wind-tossing countless times out of alignment, then being prevented from regaining alignment—than from a stem's inner weepiness. The graceful habit of Muhlenbergia dumosa is both created and maintained by the wind.

 

What would a clump look like if growing where the air were never in motion? Without being nudged out of alignment by the wind—yanked, even, by the gusts and storms—would stems grow more densely and stay more erect? Even in a greenhouse, there are ventilation fans and doors that open and close; we may never know the shape a colony of bamboo muhly grass would assume without the assistance of air in motion.

 

 

Here's a closer look at Eucomis pallidifolia ssp. pole-evansii and Eucomis 'World Peace' in bloom, plus links to other cultivars and the full story on how to handle Eucomis.

 

Here's a look at another daylily cultivar, the strikingly late and miniature-flowered 'Wee Willy Winkie'—as well as information on how to handle daylilies in general.   

 

Here's how to grow Muhlenbergia dumosa

Latin Name

Muhlenbergia dumosa

Common Name

Bamboo muhly grass

Family

Poaceae, the grass family.

What kind of plant is it?

Clumping perennial grass; grows quickly when young, so can also be used as an annual. 

Hardiness

Zones 7 - 10.

Habit

Many slender but wiry stems emerge from a dense base. With assistance of the slightest breezes, but stiffening resistance of the wiry stem, their profuse upper side stems and foliage cause them to arch outward instead of merely flopping over. The result is a gloriously billowing and airy canopy of growth that is, nonetheless, sturdy and resilient. It ruffles and rearranges in even slight breezes; even after strong wind, the clump's canopy of growth reassembles gracefully. Unlike many a clump of Miscanthus that, by September, has split open as if squashed by the gods, clumps of Muhlenbergia seem to be playing in the wind, not just withstanding it, all season long.

Rate of Growth

Fast.

Size in one season and in five. 

Muhlenbergia dumosa grows quickly, either from seed or from plugs; even in a single season, plants can grow to three feet tall, and produce enough stems to form acceptably full clumps. Because of the unusual number and length of side stems along the top half of each stem, the volume of even a half dozen stems can large enough to form an acceptably full look. See "Grown for," below.

 

In climates mild enough for this grass to overwinter easily—or if it is grown permanently in a container and receives necessary protection—clumps can become four to six feet tall and wide.

Texture

Supremely feathery and graceful. The only plant in the grass family whose foliage and habit even approaches that of Muhlenbergia dumosa in delicacy is the subtropical (and much larger) bamboo Otatea aztecorum.

Grown for

its extraordinary texture: The individual leaf blades of Muhlenbergia dumosa are about three and a half inches long, but are very slender—a sixteenth of an inch wide. Even so, this species' exhilarating airy look depends as much or more on the structure of the stems that bear the blades. Unusual for grasses that are not true bamboos, stems of Muhlenbergia dumosa are well-branched. The main side stems form small side stems that, in turn, branch out themselves. The leaves are borne only on these smallest side stems. The combination of generous branching and long narrow foliage enables a single stem's overall volume to be sizable even though the bulk and weight of actual plant material—stems and leaves combined—is minimal. Hence, the startlingly airy habit.

 

its billowing, cascading, and even weeping habit—which, surprisingly, is not a result of any weeping tendency of individual stems; when solo, each is erect. See the article, above, for the solution to the puzzle of stems that are upright as individuals, but wide-spreading and cascading en masse

 

its ease of handling: Although established clumps are so drought tolerant they can partner cacti and succulents growing in lean, fast-draining soil, Muhlenbergia dumosa can also be grown in more moisture-retentive soils as long as they are very well-draining. It also thrives for the long term in a container. See "Where to use it in your garden," below.

Flowering season

Late Fall into Winter: Tiny greenish-white flowers in short panicles emerge from the leafy tips of the "stemlets." Perhaps in temperatures that are cooler than my greenhouse, which is frost-free but heated only to fifty degrees Fahrenheit, they take on a faint pink hue. The flowers bring an added note of fluffiness—or even, on a chilly morning, fogginess—to the look of a clump, but would never be thought of as anything but secondary to the high drama of the feathery foliage. They are both tiny and innumerable, so only a patient fetishist would consider clipping them away to maintain purity of the green show of the foliage. Flowering stems are removed in late Winter, anyway—see "Quirks," below—so be patient that extra month or two.

Color combinations

The light green foliage goes with everything. Bamboo muhly grass doesn't flower until Fall or Winter so, when used as a warm-season annual or container specimen, its flowers' pale-to-pinkish tones aren't relevant. If you grow Muhlenbergia dumosa where its cool-season flowers are prominent, you'll want to surround colonies with plants that are celebrating blue, pink, and burgundy; avoid those whose Winter display emphasizes saturated shades of yellow, orange, and red. 

Plant partner

It's hard to go wrong by growing Muhlenbergia dumosa near plants whose foliage is much larger and whose habit is stiff or at least not ethereal and "floaty." If your climate is Zone 7 or warmer, and you can provide the excellent drainage needed, you could grow bamboo muhly grass in the ground, pairing it with whichever forms of agave, aeonium, cactus, euphorbia, and phormium will thrive. In my garden, Muhlenbergia dumosa is tender, but I can create plenty of sizzling combinations with container plants such as Euphorbia cotinifolia, Furcraea foetida 'Medio-Picta'Kalanchoe beharensis, Strelitzia reginae 'Mandela's Gold', and Yucca gloriosa.

 

Perhaps in 2016, I'll group pots of bamboo muhly grass around my large tub of Arundo donax 'Peppermint Stick', whose mighty, thrusting corn-like canes and large, thick white-striped leaves could scarcely be a stronger contrast. Or around my biggest pot planted with 'Australia' or 'Russian Giant' cannas; each has burgundy banana-sized foliage. 

 

Bamboo muhly grass could also be a flowing underplanting around taller plants with narrow bases and large-leaved canopies that don't cast much shade: palm trees with palmate not pinnate fronds, say, or cordylines. These options are all tender for me, but I can choose among my container specimens ofBrugmansia,Cussonia paniculata, and Trachycarpus fortunei.

 

One happy but unexpected consequence of bamboo muhly grass's amenability to grow in containers either for the season or forever, is that the species' in-ground requirements for good drainage and a Zone-7-or-warmer climate don't need to dictate the partner plants. The Arundo grows best in soil that is saturated; each Spring, I set my huge pot of it in a galvanized tub that I top up with water daily. Brugmansia and canna perform best over the Summer when growing in rich soil that is fertilized lavishly. 

Where to use it in your garden

Where hardy, Muhlenbergia dumosa can be used flexibly and creatively as a permanent garden feature. It is drought-tolerant enough to be ultra-contrasting filler among succulent perennials, shrubs, and trees, whose thick water-storing features often make them look heavy, rigid, squat, and immobile. Its growth is regular enough, clump to clump, that the grass can function as a large-scale groundcover, or an informal low hedge. Its heat tolerance makes it comfortable even when billowing out onto stone, brick, or gravel walkways, which can become broiling hot under unrelenting sun—while its stems' feathery grace and catch-every-breeze motion are the perfect visual relief for such static, heat-radiating hardscape.  

 

Quick growth, beauty that only increases through the growing season, and tolerance of heat and drought all make bamboo muhly grass an easy keeper in a container, whether as an annual or starter plant just for the season, or as a permanent specimen nurtured year after year.

 

Provided colonies are groomed in early Spring to remove now-dead stems from last season, they seem to drop little or no foliage, let alone stems, throughout even a long growing season. Plus, flowering doesn't happen until late Fall and Winter. On both counts, Muhlenbergia dumosa could be stunning as well as practical alongside swimming pools and ornamental water features that are in use just Summer and Fall, because it wouldn't shed leaves or flowers during the active season even if placed such that its billowing growth extended directly over the water's surface. And even where the climate is mild enough that water features would be in use through the Winter, bamboo muhly grass might still be easy: Its flowers are tiny and comparatively sparse, while its leaves are nearly thread-like; if some of either fall into the water, they are unlikely to clog any normally-maintained system. Plus, if a clump receives a weekly go-over after flowering is through and as those stems die, "at risk" stems are both easy to identify (they have turned the color of straw) and to clip out.

 

Muhlenbergia dumosa is reportedly not fond of having its current-season's crop of stems cut back while still green, which might be necessary if clumps were sited too close to narrow pathways. Stems are reported to produce new growth only fitfully in response. Fully extended stems of mature and vigorous clumps can "fluff outward" three feet or more from the clump's dense base, and staking or tying them back—or pruning—would destroy the species' casual elegance. Site bamboo muhly grass where you can allow it whatever space it wants.

 

See both "How to handle it" boxes, below, for how to keep Muhlenbergia dumosa looking its best in all of these contexts. See "Plant partners," above, for suggestions on what looks great growing near bamboo muhly grass, whether just for the season or for the decade. 

Culture

Full sun and almost any soil that is well-drained, even those that are lean and dry. When growing in the ground, Muhlenbergia dumosa tolerates heat and drought despite its seemingly fragile appearance; it is maximally lush when it receives occasional supplemental water. In containers, root room and available water are both inherently limited, so supplemental water is essential. Muhlenbergia dumosa won't tolerate bad drainage at any time.

How to handle it: The Basics

Plant bamboo muhly grass in Spring, ensuring enough water for establishment. As is typical for ornamental grasses, clumps don't need attention as they launch themselves—nothing like the pinching or staking of annuals or perennials, or the pruning and tying-in of most woody plants and vines.

 

If growing directly in the garden, little care is needed other than cutting out stems as they die after flowering. Would bamboo muhly grass be a prolific self-seeder where the climate is mild and the soil is well-drained (as would often be the case in its native northern Mexico)? In that case, you might want to cut flowering stems before their seed has matured. Maturation is likely to be complete just before the stems turn yellow and die, so you'll want to clip out flowering stems sooner than when self-seeding isn't a problem.

How to handle it: Another option—or two!

Growing Muhlenbergia dumosa in a container just for the season couldn't be easier: Plant in Spring, water only when the top of the soil feels dry, and enjoy.

 

To enjoy this species year to year in a container, bring into protection each Fall before hard frost, supplying all possible light. As long as they are above freezing, cool temperatures, especially at night, are fine. Water only as needed. Unless you add artificial light, the light experienced by plants being kept under glass or the "poly" of a hoop house is always much weaker than that experienced outside. So growth will slow both because of shorter Winter days and weaker ambient light.

 

Even a young clump of bamboo muhly grass could take up way too much space on a greenhouse bench if allowed to billow ad libitum. Instead, tie the stems loosely together in a vertical sheath of growth, whose footprint need not be wider than the plant's pot itself. If this tying-in creates a silo of foliage that's now awkwardly tall, cut it down just to the lower side stems, so that some of the clump's foliage remains. It's not a great look, but is only temporary: All of these stems will be fully pruned out as Winter turns to Spring. Again, water only as needed, first allowing the top couple of inches of soil to feel dry, and the container to feel noticeably lighter overall.

 

Let flowering occur, and let stems that have flowered mature and die. If you've needed to "silo" your pot of bamboo muhly grass, you won't be able to cut off dead stems at the ground easily, nor extract them, one by one, up through the dense tied-in growth of the still-living stems. Instead, leave them in place, doing all possible clean-up at once, as Winter slides into Spring, when you untie the colony and release the stems to their billowing normality. Even so, it's likely that the last of last season's green-leaved stems will continue to mature even as the pot is returned to the outdoors after frost danger is past. In my experience, a containered specimen of bamboo muhly is surprisingly skimpy in late Winter and Spring, with most new stems emerging only after the colony is in place outdoors for the season. In a way, this is all to the good, in that the overwintering colony takes up the minimum of always-scarce greenhouse space from Fall and Winter even to early Spring, when it's still too chilly to set pots outside again.

 

I'm growing my colonies in three-gallon nursery pots, which are sunk into larger terra cotta pots for the Summer. So far, more is more: A clump of bamboo muhly grass that is four and five feet tall and wide is more exciting than one that is just three feet tall and wide. In early Spring, I'll slide my clumps out of their nursery pots to check if potting-up would be needed. Still, a clump in a five- or seven-gallon nursery pot will probably grow nearly as large as one growing directly in the ground in a mild climate. So in a year or two, the clumps will be in a steady state, pot-wise. I might divide them in early Spring, repotting in fresh soil only the portions that seem most active—but I won't repot into a larger container.

Quirks and special cases

Muhlenbergia dumosa is reported to be touchy about the renewal pruning so often performed on ornamental grasses: Cutting them down as low as possible to the ground in early Spring, before new growth emerges. This wholesaler says, flat out, not to prune stems shorter than six to eight inches. And yet, stems are monocarpic—meaning they flower once, then die—and, worse, turn tan in death. They then need to be removed lest they interfere with the ravishing soft green display of the live growth.

 

I keep just a few container specimens, which I go over in late Winter, stem by stem clipping dead ones off at ground level. But in milder climates, Muhlenbergia dumosa lends itself to mass plantings, where such detailed attention would be madness. Instead, prune back to six or eight inches with shears or a string trimmer just before the new generation of stems is likely to emerge. If you must cut living stems back during the growing season—perhaps a deer took a fancy to sleeping on your colonies, or kids trampled them during touch football—leave as much of the live growth in place as possible even if that means stray half-mast stems abound. After they've flowered and died over the Winter, then cut them down the rest of the way.

Downsides

Muhlenbergia dumosa is usually listed as hardy to Zone 7 at the coldest, but it's common for sources to state the lower limit of hardiness just to Zone 8. This species grows quickly enough to enjoy as an annual—but a container-grown specimen is worth overwintering, and will be even larger the next season. See the second "How to handle it" box, above.  

Variants

I'm not aware of any cultivars, which is no matter in that the straight species is so striking and successful it would be hard to improve upon it. Still, imagine a form with foliage that's burgundy or blue or yellow! And it would be such a help if any form emerged that were hardier.

Availability

On-line and at retailers.

Propagation

By seed: Bamboo muhly grass grows fast enough to succeed as an annual. Clumps could be divided in early Spring, just as new growth is emerging.

Native habitat

Muhlenbergia dumosa is native to southern Arizona and northern Mexico.

 
 
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