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never seen before & figuring out how to make them perform.- The Boston Globe

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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

Crab Cactus

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Behold, a truly tragic crab cactus, which I've neglected for so long that the stems are visibly wrinkled and droopy. A quick dunk in a pan of water has yet to bring signs of relief. And yet, look at all the flowers! Day-glow shades are the norm for Schlumbergera truncata, although white and pastel pink or yellow are also available. In its native Brazil, crab cactus grows in trees, so its downward-facing flowers are readily accessible to the preferred pollinator: Hummingbirds.

 

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Only when a flower is tipped upright are details of the interior discernible. The white stamens are tipped with yellow pollen, while the stigma—the tip of the raspberry-hued style—is electric pink. 

 

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When seen from below, the translucent petals bathe the style and stamens in such concentrated pink light that their actual coloring isn't apparent. Such subtleties aren't of concern to the hummingbirds, which are interested in the plentiful nectar deep in the interior of the flower. For them, the pollen is irrelevant in any color, and pollination is inadvertent.  

 

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It's often tricky to bring Schlumbergera truncata into flower. But, as my sorry specimen proves, as long as a crab cactus plant receives the necessary coolness and long nights, the plant can power through neglect, to achieve a truly colorful performance. Imagine the show if I treated this plant with the respect it deserves. I'm on it. 

 

 

Here's how to grow this extraordinarily showy succulent:

Latin name

Schlumbergera truncata

Common name

Crab cactus / Thanksgiving cactus / Claw cactus

Family

Cactaceae, the Cactus family.

What kind of plant is it

Thornless tropical succulent.

Hardiness

Zones 10 to 12.

Habit

Mounding and shrubby. Arching and cascading branches are formed by chains of thornless, flat, green stem segments, known as cladodes, that function as the plant's leaves. Eventually, cladodes at the lower portions of the stems thicken, becoming rounder, rigid, brown-barked, and woody.

Rate of growth

Medium; speed of growth depends on culture and handling.

Size in ten years

Mature size of the plants is dependent on age, handling, and culture. In containers, usually less than a foot tall and one to two feet wide; somewhat larger when growing in the garden.

Texture

Linear and ropy: The branching chains of flat green stem segments, which arch outward and eventually cascade, have a distinctive if modest rhythm.

Grown for

Its brightly colored flowers: The flowers have twenty to thirty tepals, the term used when there's little difference in look or function between petals and sepals. The outer ring of these reflect back, whereas those in the inner rings tend to be fused at the base to form a narrow cone that only broadens out at the tips. The result is a long flower that will strike most viewers as being double or "hose in hose." Although newer forms of Schlumbergera bear flowers that are white, pale yellow, or pink, the naturally-occurring colors are vivid shades of magenta, orange, and scarlet, often with a paler inner petal surface. There are also bicolor forms, with just the outer edge of the petals darker. To my eye, these are too interesting by half: The flowers are already large, profuse, colorful, and exotic in shape. Gardeners in the favored mild climates where Schlumbergera can be grown outdoors will enjoy the flowers' popularity with hummingbirds. 

Its tolerance and relative ease of handling: Schlumbergera is famous for enduring year after year, usually because of the neglectful handling that saves the plant from the certain death that results from overwatering. Bringing a crab cactus into bloom is another matter: See "How to handle it," below.

Flowering season

Usually by late November—hence one of the common names, Thanksgiving cactus—and continuing into December. 

Color combinations

Schlumbergera offers a wide range of flower colors: white, pale yellow, pink, rose, magenta, orange, and scarlet. Although there are pastel shades, there are no dark ones—no burgundy, terra cotta, or grape-purple. In any shade, then, a crab cactus in bloom is a bright presence; it's best to surround it with horticulture in neutral greens, or the dark colors its flowers can't achieve on their own. Burgundy coordinates with any of the cactus flowers' shades; terra cotta works well with any of the orange or scarlet hues.

Partner plants

Few gardens provide the foggy but frost-free conditions that Schlumber- gera needs to thrive when planted directly in the garden, and so crab cactus is most often enjoyed as a container plant. Despite this seeming portability, there are enough quirks in the process of bringing the plant into bud—and then into flower—that it's best not to reposition it during the entire bud-and-bloom season. Any partner plants will need to enjoy, or at least tolerate, the same specific conditions. See "How to handle it," below. 

Crab cactus flowers are not just eyecatchingly colorful; they are also structurally complex and visually voluptuous. So it's usually a mistake to pair Schlumbergera with plants whose primary appeal is also floral: If their flowers are so prominent and complicated that they don't appear out-gunned by those of Schlumbergera, the combination risks looking jangly and even juvenile, like a cake with green-and-pink frosting an inch thick. It's easier to welcome Schlumbergera as a temporarily-floral highlight to a display of foliage plants whose appeal is more constant year-round. 

What container plants are also lovers of shade and humidity and—most importantly—also require or at least tolerate cool and very long nights in Fall? Shade-lovers from the warm tropics, such as caladiums and elephant ears, are likely to fall into dormancy, if not rot outright, in the coolness that crab cactuses appreciate. Instead, choose among ferns, clivias, aspidistras, tropical gingers, camellias, Winter-flowering begonias, gardenias, and philodendrons. While most of these plants' foliage is various shades of green, there are plenty of begonias, and a few philodendrons and gingers, whose foliage is exuberantly colorful.

Where to use it in your garden

These frost-tender plants' flowering season—when the days are shortest and, often, the temperatures are most likely to fall below freezing—limit their use directly in a garden to locales whose cold season is merely cool at the worst. But climates that are frost-free by dint of outright warmth—Aruba any day of the year, say—aren't suitable, either: Temperatures above ninety degrees Fahrenheit, especially during the flowering season, are likely to cause bud drop. Instead, Schlumbergera flourishes in areas of tropical latitude (inside of, or at least not far outside of, the equatorial band between the Tropics of Cancer and Capricorn) at cooler elevations of over 2500 feet above sea level.

Farther north or south of those favored locales, Schlumbergera is a popular container plant, happy indoors or out wherever it receives high humidity and shelter from strong sun and temperatures that are rarely above ninety and never near or below freezing. Site in dappled shade all day, or where the plant receives direct sun only in the morning. 

Culture

I have only been to Brazil once, over thirty years ago, and didn't know to look for these natives growing where they grow best: In humid shady coastal subtropics, several thousand feet above sea level, where Winter temperatures can be cool but rarely below freezing, and where the high elevation means that warm moist air from the nearby sea rises high enough to condense into fog and light rains. In complete contrast with the habitat of the cacti of popular imagination—piercingly strong sun and baking heat, with weeks and months between rain—all forms of Schlumbergera thrive in circumstances more common to delicate ferns: Higher humidity, with bright but indirect light.

How to handle it: The Basics

Schlumbergera is strikingly tolerant of abuse, partly because our common sense of plant "abuse"—low light, not being repotted for years, sporadic watering, being left on a cool dark porch instead of being brought into warmer and brighter shelter—actually describes most of the conditions these plants require for a successful yearly flowering cycle: Dappled shade, a shallow and usually restricted root-run, occasional drought rather than overwatering, and cool nights and short days as prerequisites to bud formation as well as flowering.

Most likely, you'll be buying Schlumbergera as a small plant— ideally, a small flowering plant, so you can confirm the flower color. No problem:

Schlumbergera blooms when very young, and is usually for sale at retail locations only when in bloom.

If you buy from a succulent specialist, though, you might be purchasing unrooted segments of cladodes. Yes, you won't have direct in-the-flower verification of the color of the blossoms, but you do have the integrity of the specialist to rely on, plus the accuracy of its catalog's description and pictures. To root the cladodes, see "Propagation," below. 

Although Schlumbergera will tolerate dry periods, you'll achieve quicker growth and more flowers with regular watering and, in Spring and Summer, light fertilizing. Take time to get the sense of how much and how often to water, so you keep the plant's soil at a "Goldilocks" point: neither excessively dry nor moist. 

As demonstrated by the commercial crops of millions of in-bloom crab cactuses available each November, bringing a Schlumbergera into bud and then into flower isn't rocket science. But the process is definitely quirky.

The key is to provide at least a month of the following two conditions as Summer shifts into Fall: 1. Short days and long nights: Twelve or even sixteen hours of complete darkness, please, with absolutely no inter- ruptions from artificial light. 2. Temperatures that are cooler than you yourself would probably prefer: Sixties into seventies Fahrenheit during the day, and low fifties or even cooler at night. Temperatures much cooler than the mid-forties at night are likely to induce dormancy instead of bud formation.

Given that Schlumbergera flowers in late Fall and early Winter, when the weather is increasingly cold and days are naturally at their shortest, you'd think that achieving these bud-inducing conditions would be easy. Alas, the short days are just when we use artificial lighting the most. And for many gardeners, local seasonal temperatures are far colder than the cool that Schlumbergera requires. Crab cactus recovers only from minimal frost, which also destroys that year's flowers. The ideal would be to have a protected porch or a rarely-used room, whose windows receive morning sun only and whose heating you don't turn on. Then, the cactus can enjoy its natural "budding season" conditions of soft daylight, long nights, and frost-free coolness. If you have access to a stingily-heated greenhouse that doesn't need to be lighted, and doesn't receive spillover from the ambient light of surrounding buildings, that's another solution.

Throughout this bud-formation period, continue your "Goldilocks" watering as normal; witholding water does not encourage bud formation. When the cactus becomes loaded with buds, try to resist relocating the plant to conditions that make appreciation of the blooms-to-come any more comfortable: If the plant experiences higher temperatures, better lighting (and, certainly, lighting past dusk), or even unexpected drafts or hot spells, buds can be shed. Instead, if you've found a location that works best for bud formation, leave the plant alone and make accommodations yourself to enjoying the show under those circumstances: View it only during the daytime, wearing wool socks and a sweater as needed.

Such admittedly specific and even picky conditions mean that a crab cactus in bloom is usually on display as a single container plant, without any partner plants nearby. Unless you enjoy a collection of crab cacti, you might not be liable to have many other container plants that require the same conditions, or even tolerate them. For suggestions, see "Plant partners," above, as well as "Where to use it."

After flowering is completed, withold fertilizer and be extra careful not to overwater: In the continuing shorter days and cooler nights of Winter, the plant will need even less water. Indeed, you may find that the plant enters of period of dormancy, during which water uptake from the soil is noticeably reduced. Let the plant guide you on how often or infrequently you should water.

Lengthening days later in Winter usually bring the plant out of dormancy, which you'll be able to confirm by the emergence of new cladodes at the tips of the current ones. Slowly increase watering to keep pace. Although Schlumbergera is content growing in a container that seems small, now's the time to repot, especially if your goal is to increase overall plant size. Choose a pot that allows only an inch or so of additional room all around the current root ball. Because overwatering is far more often the cause of failure than underwatering, grow Schlumbergera only in containers made of unglazed terra cotta, and with a drainage hole. The natural pores of terra cotta will facilitate evaporation of excess water. Conversely, if the plant becomes so dry it wilts, you can plunge the entire plant, pot and all, into a sink of room-temperature water. The pot itself will absorb water and pass it inward, into the soil, as needed.       

Place Schlumbergera outdoors only after all danger of frost is past; choose a location that is spared hot mid-day and afternoon sun. If you grow orchids and Summer them outdoors in dappled shade, that's the same exposure to provide for your crab cactus.

How to handle it: Another option—or two?

Breeders are striving for forms that are more upright, but you could help your own crab cactus gain more height each time you repot. Older stems become woody at the base and, so, are self-supporting. During repotting, tilt the rootball in the new, larger, so that the bases of the most prominent stems are vertical; cut off old stems that have become angled farther outward as a result. After two or three such repottings, you'll have encouraged vertical woody growth, which will hold the canopy of arching chains of green cladodes more centrally over the base of the plant. In effect, you'll be forming your crab cactus into a small weeping tree.

Any (other) quirks or special cases?

In its native habitat, Schlumbergera is epiphytic, and grows in trees. The flowers face downward—possibly to protect the pollen from the frequent mists and rains—but, because of the plant's elevation, are still readily accessible to hummingbirds.

Schlumbergerais typically wider than tall, with stems that cascade below the bottom of the container. Display your crab cactus as high up as you can, so that you can get a hummingbird's view of the flowers' colorful yellow pollen and the (often) brighter inner surface of the tepals. Ideally, grow in a hanging basket that you can suspend from a wall bracket, or from the cross-beam of a shady pergola. Table-top display can also be effective if the plant is placed on some sort of a stand; the easiest is an inverted terra cotta pot. 

In their native Brazil, crab cactus is known as flor de Maio: May flower. At first, this could suggest that Schlumbergera actually prefers to flower during a season when the days are becoming dramatically longer as well as warmer. But in the Southern hemisphere, the seasons are reversed: The day length is shortening in May as Winter approaches, with the shortest day of the year at the solstice in June.

Downsides

Schlumbergera are spectacular in flower, but can be a snooze the rest of the year. Alas, none of the rare variegates are, to my eye, successful. The cladodes of 'Madame Butterfly' can have creamy edges or can be all cream except for a central green vein—but the flowers are a bicolor of hot-pink and white. Ugh.

Variants

There are six species of Schlumbergera; differences among them are subtle to anyone other than aficionados. Cladodes of forms derived mainly from S. truncata have points. Flowers are held more horizontally, bear yellow pollen, and are more likely to appear closer to Thanksgiving. Cladodes of forms of S. x buckleyi are more smooth-edged. Flowers are more pendulous, bear pink pollen, and are more likely to appear around Christmas. Although the main parent of all forms of S. x buckleyi is S. russelliana, there's usually some S. truncata in the lineage, too. Did I say that the differences are subtle?

 

In addition, there are still more forms derived mainly from S. opuntioides or S. orssichiana, let alone hundreds of hybrids and cultivars across all the species. Plus, flower color and timing can be affected by differences in temperature, watering, and exposure to light.

 

Breeders strive for forms with a more upright habit, especially when young, as well as flowers that are less pendulous. Forms that are more pendulous could be mistaken for being wilted, plus their pots can't be grouped as closely together during propagation or on the sales benches.

If the later flowering season is important, choose one of the S. x buckleyi forms. For earlier flowering, choose one of the S. truncata forms. Flower colors across the genus range from white and pale yellow to apricot, orange, pink, raspberry, and red; there are also bicolors with white. Unless you're shopping from an on-line specialist, you'll only know which group you might be buying from if you purchase plants when they're in flower. Those appearing first at nurseries in the Fall tend to be the S. truncata forms.

The habit, culture, size, and segmented stems of Hatiora gaertneri are very similar to those of Schlumbergera, but the showy flowers are much simpler in structure: They might remind you of those of gerbera daisies. So-called Easter cactus flowers months later than crab cactus: April into May. It is reported as being a bit fussier, and to form buds it needs needs cooler Winter temperatures: high forties to low fifties, Fahrenheit. I can see one in my future.

Availability

On-line and at retailers.

Propagation

Easy, by rooting the cladodes. If you are propagating from your own Schlumbergera; pull them free instead of cutting.

 

In either case, let the cladodes dry for a few days so their ends callus, then pot shallowly (or just lay directly on the soil surface) in a growing medium composed of equal parts peat moss and something inert and gritty, such as perlite or sharp sand. Shallow pots are best: Schlumber- gera is not deeply rooted and, as with succulents in general, it's wiser to limit the available mass of soil so that there isn't excess that remains unpenetrated by plant roots, and which could, therefore, retain moisture and increase susceptibility to rotting.

 

Water sparingly until the cladodes have rooted and begun to produce additional segments

Native habitat

All Schlumbergera species are native to higher elevations of coastal mountains of southeast Brazil, including the states in which the cities of Sao Paulo and Rio de Janiero are located. S. truncata has been cultivated in Europe since 1818; S. russelliana in 1839. An Englishman, W. Buckley, hybridized the two in 1852, originating the S. x buckleyi group. 

 
 
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