A Gardening Journal

The Best Season Ever: Swamp Crinum

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Crinum erubescens is hard to beat for hot-weather drama, with huge fragrant flowers and weird-wonderful pink stamens. In Winter, swamp crinum couldn't be easier: Staying green if the weather's mild, going dormant if it's colder. The plant isn't reliably hardy in New England, so I grow my colony in a large container that sits out the winter dry in the basement.

 

The flower buds are blushed with burgundy and yellow. When the flowers open, the surprise is the almost comically dramatic stamens. Not just lengthy, not just tipped with banana-like gold anthers, they are also bright pink shading to raspberry.  

 

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The flowers' size and giddy appeal makes pairing with other flowers a challenge; see "Plant partners" for suggestions. It's easier and, as the display below suggests, completely exciting when swamp crinum can be the floral star amid spectacular foliage plants.

 

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Even in bud, Crinum erubescens is a thrill. 

 

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The buds' length and subtleties of coloring—notice how the tip is the same shade as the thick flower stalk—are a pleasure in combination. The feathery rush at the back is Elegia capensis, which thrives in the same sun, heat, and moisture level as swamp crinum. Its delicate texture enhances the buds' big-boned appeal.

 

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Here's how to grow this high-performance perennial:

 

Latin Name

Crinum erubescens

Common Name

South American swamp crinum

Family

Amaryllidaceae, the Amaryllis family.

What kind of plant is it?

Perennial bulb.

Hardiness

Zones 7 - 10.

Habit

Thick-growing and, when given the opportunity, wide spreading. 

Rate of Growth

Fast when happy.

Size in ten years

Size depends on culture, climate, and handling. In mildest climates, growing in-ground in swamps, Crinum erubescens will extend indefinitely, much like cattails do in swamps in colder climates, thanks to vigorous and far-reaching rhizomes. Outward expansion is slowed but not stopped when growing in regular garden soil. The umbels of blossoms extend above the foliage, and can be three feet high; the foliage itself isn't usually taller than thirty inches. 

Texture

The foliage is, admittedly, as coarse as that of bearded iris or daylilies. As with both of these ever-popular plants, the sensational large blossoms more than make up for it.

Grown for

everything to do with its flowering: Flowering stalks—known as scapes—emerge at the sides of the ever-unfolding crown of leaves. At first, the scape is green; because it is nearly as thick as the strap leaves are wide, its presence is usually a surprise. As the scape matures, it turns burgundy, calling attention to the pale-green sheathed umbel of buds at its tip. The buds lengthen far beyond the dimensions of the sheath, and array themselves in a loose circular mound. Including its stem—the pedicel—each bud is easily eight inches long. And it is ravishing: The tip of the tightly closed flower is burgundy-blushed, whereas the pedicel is greenish yellow.

 

In a day or two, catching you by surprise, buds have opened into fragrant daylily-like flowers. In reality, they begin opening at dusk but, often, you won't have discovered that until the next morning. The bud that was fully closed one day has had plenty of time to progress to full openness by the morning of the next. The inner surface of each pure white, backwardly-curving petal creates all the more contrast with the raspberry-stemmed stamens. They are arrayed in an orderly fashion, each one lying along the middle of "its" petal. These stamens curve outward four inches or more, and each but one is tipped with a large banana-shaped anther that is soon ripe with gold pollen. The lone anther-less "stamen" is the pistil, which receives the pollen. As is typical of flowers that are white as well as fragrant and fully open at night, the flowers are pollinated by nocturnal moths. The flowers mature to seeds whose size increases if the plant receives more nutritious soil and greater access to water; seeds of aquatically-growing Crinum erubescens can be an inch in diameter.

 

 

its durability: Crinums are famously long-lived. Like Rhodophiala, crinums continue to performing beautifully even on long- abandoned property. Because these perennials' longevity was already known at the time of original planting, their siting would have been well-considered. The location and configuration of these perennials therefore has a certain archeologic value, suggesting the locations of previous structures and garden beds.

 

 

its imperviousness to browsers:  As is typical for the genus, the foliage of Crinum erubescens is avoided by grazing animals.

 

 

its flexibility: Crinum erubescens is opportunistic, succeeding as an aquatic planted in-ground, as a container plant growing seasonally or permamently in a water garden, as a perennial growing in regular garden soil, and as a seasonally-deciduous container plant that accepts months of unwatered dormancy late Fall through Winter.

Flowering season

July through frost. Depending on the size of the colony, the mildness of the climate, the richness of the soil, and the availability of water, flowering can range from sporadic to nearly continuous.

Color combinations

The green foliage, burgundy scapes, pure white flower petals, yellow-green pedicels, and deep yellow pollen of Crinum erubescens enable it to mingle with neighboring plants that explore a broad range of coloristic possibilities. Two things are clear: First, when swamp crinum is in bud, it's working with enough colors—burgundy, white, yellow, and green—already. Choose surrounding plants that add more of the same yellow, white, burgundy, or green. Second, it would be cacophonous to introduce yet another hue, such as blue or red.

 

But overnight, the buds become flowers that flaunt raspberry-colored stamens as glamorous as they are prominent.  A plant that didn't have a thing to say to pink when it was in bud yesterday is speaking pink like a native today. If you can, then, site Crinum erubescens near other pink-friendly plants. If you prefer (as I do) to keep the focus on this species' yellow-white-burgundy-green palette, think of these pink parts as horto-humor: Great fun, but not, in themselves, worth the effort to provide swamp crinum with an extensive and pink-focused setting.

 

To pink, or not to pink? See "Plant partners," for suggestion for either choice.  

Plant partners

If growing swamp crinum in-ground, your choices of plant partners would be guided as much by the necessity of keeping the crinum colony from overwhelming them, as by aesthetic niceties of color or scale or texture, or even cultural compatibilities of growing other moisture-loving plants nearby. Don't try to establish anything smaller near the crinum. Instead, choose woody plants, or large-scale perennials such as aroids, or ferns whose roots form mounding or trunk-like bases, whose emerging growth can be every bit as thug-like as that of the crinum. Then, the crinum can flow around the base of these larger neighbors, whose overhead growth will still receive necessary sun.   

 

When you grow Crinum erubescens in a container, your options are much broader because colony size is easy to control: Just clip off outward-bound rhizomes, letting the aesthetics of potential neighboring plants lead the way instead of their immunity from being swamped by the swamp crinum. Although the crinum flowers are stunning, they are ephemeral. The less-interesting green and strappy foliage is ever-present as long as the weather is warm. Partner the crinum, above all, with plants that provide strong foliar contrast, in size, shape, and, if possible, color. I surrounded my crinum with the banana-like leaves of 'Striped Beauty' canna; this canna also thrives aquatically (and in containers), and its leaves have unusual thin creamy stripes and strips of dots. The grassy foliage of gold-leaved sweet flag is so narrow it makes the daylily-like leaves of the crinum seem broad, while its gold color is a sharp change from the medium green of the crinum. Anything ferny would also be a winner; I dragged over my colony of the feathery-leaved horsetail rush, Elegia capensis.

 

Each of these choices is pink-neutral: None enhances the delicate shock of the crinum's showy pink stamens, but none clashes, either. But here are two plants that make an explicit pink link, and each enjoys the same range of soil moisture: 'Red Flyer' hibiscus, and 'Erebus' canna. If you're growing Crinum erubescens in a container that you set into a water garden, you could combine it with a container of 'The President' or 'Russian Red' lotus. Because both the crinum and the lotuses are notorious colonizers, growing each in a container is the way to keep them separate.

Where to use it in your garden

If Crinum erubescens is hardy where you garden, it can be used as a rough-and-ready groundcover anywhere it has access to enough soil moisture. Surface dryness, which could be readily apparent if the soil is heavy clay as much as pure sand, is not a deal breaker: The roots of crinums are legendary for their far-reaching as well as deep colonization of their beds. As long as there is moisture farther down, the plants will thrive.

 

This vigorous colonizer is difficult to restrain, and will quickly overwhelm smaller neighbors. It is also able to spread into adjacent lawn, where its leaves, which continue to emerge from the underground rhizomes despite regular mowing, look like those of a coarse weed. Contain swamp crinum by growing in a large container sunk into the ground, or by planting alongside paving instead of grass. Swamp crinum is also very much at home when growing aquatically, whether planted in the bottom soil of a natural pond, or growing in a container that has been placed in a hard-bottomed water garden or, simply, plunged into a large tub. 

Culture

Sun and almost any soil, saturated or not—including clay—that doesn't become dry.  

How to handle it

When growing Crinum erubescens aquatically, plant in Spring. If growing in a container, just use an inexpensive black nursery pot. If sited at the edge of natural-bottom ponds or in their shallows where Crinum erubescens is solidly hardy, no further care is needed for establishment. (See "Quirks and special cases," below, for possible assist in establishing in colder climates.) If growing in containers for placement in a water garden, plant the container on dry land first, then settle it slowly into the water garden. If placing in water deep enough for full submergence, mulch the soil surface with heavy gravel first, so that the soil and the plant remain in place during the submergence. A container of swamp crinum can also be grown just sitting in a shallow pan of water that you top up regularly.

 

If the containered water-garden specimen would experience frost during the cold season where you garden, either sink it entirely below the water surface so cold and ice can't reach it, or bring the container into shelter. If you have the space and the warmth, the crinum can be kept in active growth year-round. It's more often the case the space for overwintering is limited, in which case you can withold water entirely so that the container's soil becomes drier. The crinum's leaves will turn brown and can be clipped away, and the now-dormant plant can be stored under the greenhouse bench or in a frost-free basement.  

 

As Spring approaches, bring the container back into the light and warmth. When new foliage begins emerging, begin watering again. When resumption of growth seems sustained and vigorous, set the container back in a pan of water. Place back outside only after frost danger has passed.

 

It's not unusual for the rhizomes of containered specimens of Crinum erubescens to emerge from the pot's drainage holes. If you want, you can unpot the colony, which is often more easily accomplished by cutting the pot away from the root ball, so as not to damage these emerging rhizomes. Then clip away the rhizomes (perhaps potting them up to give to friends) and repot the mother colony in a new pot. It isn't necessary to encourage overall colony increase beyond that which can be sustained in a five-gallon pot: Swamp crinum flowers well when somewhat pot-bound. Do any repotting or dividing in early Spring, just as new foliage is emerging.

How to handle it: Another option—or two!

When growing Crinum erubescens in normal garden soil with just average amounts of water, plant in Spring, providing enough water for establish- ment. If swamp crinum is solidly hardy where you garden, little follow-up care is needed. If growing swamp crinum in a container that is not going to be placed in a water garden, or even set in a pan of water, you'll need to water frequently: While swamp crinum is flexible enough to grow in water or on dry land, "dry" only means not saturated. For soil that tends to become dry—whether because the crinum has become pot-bound in its container, or is growing in very sandy soil or in a climate with less rainfall—more drought-tolerant crinums, such as C. asiaticum, are likely to be easier.

 

Overwinter a containered swamp crinum as in "How to handle it," above.

Quirks and special cases

With exceptional flowers and vigor, you may want to try to establish Crinum erubescens in climates colder than Zone 7. Take advantage of its quickly-spreading capability by planting against the foundation of a building, so that heat penetrating outward into the soil can, potentially, bring the soil temperature around the crinum closer to what would be the necessary warmth for hardiness. From such a safe zone, the plant may be able to colonize outward by way of its rhizomes.

 

Another trick is to plant the bulb on its side—or even with the growing tip pointing slightly downward—so that cold surface water is less able to penetrate. 

 

A heavy mulch placed atop the colony after its foliage has been killed off by Fall frosts will also help—as will taking advantage of this aquatic bulb's ability to thrive in less-than-aquatic situations: Plant on a slope (perhaps one you create each Winter, by way of your mound of mulch), so that surface water flows away instead of penetrating into the soil. If you are growing Crinum erubescens aquatically, plant more deeply than usual, in water so deep that surface ice is never thick enough to reach the bottom.

Downsides

The spreading rhizomes make swamp crinum impractical for compact sites unless it is restrained. See both "How to handle it" boxes, above.

Variants

With nearly 200 species, and probably that many additional hybrids and cultivars, crinums are a big rabbit hole to fall into.  (I'm at seven and counting.)  Some, such as Crinum americanum, are strictly aquatic; others are amazingly drought-tolerant, thriving even in nutrient-poor Florida sand.  Some, like 'Queen Emma', grow from suitcase-sized bulbs with thigh-thick above-ground necks, almost like short trunks.  Some have foliage that's purple-blushed, dark purple, or variously green-and-white striped. The flowers themselves range from pure white to all possible shades of pink, sometimes striped with white, to a mid-rose. The pendulous curled-edge flowers of 'White Queen' are a peak of elegance that has never been bettered; if you grow only one crinum, this one should be it.

 

Hardiness varies greatly; forms that prefer to keep the necks of their bulbs above ground are (duh) more exposed year-round and, therefore, less hardy. Forms with bulbs that are entirely subterranean, such as Crinum x powellii and Crinum bulbispermum, can enter a dormant and deciduous phase just like that of a typical hardy bulb such as a daffodil. They can succeed as far north as Denver, Cincinnati, and southern New England. 

 

Crinum erubescens is one of the parents of numerous hybrids, but there aren't any named cultivars of just this species alone.  

Availability

On-line. 

Propagation

By seed and by division.

Native habitat

Crinum erubescens is native to Central and South America.

 
 
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