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Christmas Cactus (Schlumbergera)



Schlumbergera. It sounds like someone sneezing, yet it is the name of one of the most striking and surreal-looking plants, whose flowers appear to be invisibly stitched to look like leaping shrimps. It would make an ideal Christmas present.

Frederic Schlumberger, who patronised the work of horticultural botanists, was a leading collector of cacti and grew them at his home, Chateau des Anthieux, near Rouen. He was probably among the first in Europe to cultivate schlumbergera, which was discovered in Brazil and introduced by the Kew collector, Alan Cunningham, in about 1816.

Most people imagine that cactus in the wild eke out a precarious existence among the burning sands and rocks of deserts; however, the Christmas cactus lives epiphytically, high up in the trees of rain forests and jungles. Here it thrives on the rotting vegetable waste that gathers in the clefts and crevices of branches, enjoying comfortable dappled shade and plenty of warmth and moisture - facts that should be remembered when growing it in the conservatory or on a windowsill.

The heavy toothing on the leaves makes them look a little like shellfish claws and, in the States, it is known as the crab claw or Thanksgiving cactus. In fact, these are not leaves at all but flattened twigs growing from a thick woody rib, which is really a branch. Young plants tend to be quite upright and bushy in form but as they grow older the branches turn down, creating an attractive weeping shape.

A well-established plant, tumbling and flowing out of a hanging basket is a truly wonderful sight. It is the perfect plant for a jardiniere and, if neither jardiniere nor hanging basket is available, extra height can be achieved by putting the plant in its pot on top of another inverted pot.

The Christmas cactus (Schlumbergera x buckleyi) is a hybrid between two species - S. russelliana, which has deep pink flowers, and S. truncata, which comes from the country around Rio de Janeiro, whose flowers are variable in colour. S. truncata was probably the first introduction.

Since that first cross, which tended to produce fairly uniform mauve-pink flowers, some quite superb varieties have been developed, from almost pure white flowers (though they tend to be flushed with a faint rose) through shades of cherry red, mauve and orange.

Despite the delicacy of the flowers, these wonderful plants are surprisingly tough. I once saw a magnificent specimen which, apart from the time it was blooming, spent its life in the back of a garage. It still looked magnificent, albeit a bit dusty.

They also live to a great age, and, rather like aspidistras, are often passed on from one generation to another. In a perfect world they would obediently flower on Christmas Day, but they are unpredictable and can often burst into bloom in the middle of summer; in October, infuriatingly, so that they are over by Christmas; or somewhere around the beginning of February. However, there are ways of making them perform on their name day. Despite being fickle, they are the most splendidly satisfying plants to grow.

This family of plants, sometimes called holiday cactus, has undergone a number of name changes. Formerly known as Zygocactus, its official botanical name is now Schlumbergera.

The Christmas Cactus is a native of the mountainous rainforests of Brazil, where it grows on trees rather than in soil. When you are dealing with these plants think jungle, not desert. These cacti are not desert plants and do not like full sun or dry conditions. In Brazil these epiphytes grow high up in trees, in pockets of leaf mold and other organic matter.

Habits/Blooming Period

They are epiphytic cacti with tubular flowers with reflexed petals produced singly or in pairs at the end of protruding stems. The spindle shaped buds are about one inch long . The flowers come in a wide range of translucent colours: white, yellow, orange, pink, red, magenta. Individual flowers last about one week; one plant's display may last three weeks.

Planting/Maintenance

Soil: Holiday cacti prefer an acidic soil high in organic matter and very good drainage. A potting mix of 1 part sterilized loam, 2 parts peat and 1 part perlite is good. Refresh the soil every three to four years.

Light: Give your plant bright, indirect light. You cannot count on a plant bought in flower at a nursery or grocer on December 15 to repeat bloom at the same time the next year. Growers manipulate light and temperature to push flowering forward or to hold it back.

Temperature:Ordinary house temperatures about 20 degrees C are fine, but cooler nights are beneficial. Blooms will last longer at lower temperatures. Ideal location after flowering is a cool room (above 6 degrees C) with bright, indirect light.

Watering: Water blooming plants to keep the soil evenly moist, but not saturated. After blooming, cut back on watering slightly but do not let the leaves begin to shrivel. One of the biggest mistakes you can make raising these plants is to overwater them. When they’re blooming, they need water regularly, otherwise let the soil dry out between watering.

Humidity

A minimum of 30% humidity is best.

Fertilizing

Withhold all fertilizer during blooming cycle. When new growth begins in spring, fertilize at each watering with a soluble fertilizer applied at one half to one third strength.

Christmas Cacti respond to light feedings with diluted liquid fertilizer during spring and summer growing seasons. Use any good houseplant fertilizer or African Violet food. Stop fertilizing in early September to allow buds to set. Do not transplant or move the plant once buds have set. Resume fertilizing after flowering.

Propagation

Cuttings root easily. Take stem cuttings in summer, breaking off a terminal “leaf” pad or stem tip. Allow the cutting to dry for a few days before inserting it in a peat-based compost.

Diseases/Insects

Problems include mealy bugs and scale insects, as well as viruses that cause purple ring spots or line patterns on the leaves.

Organic Controls

Plants with mealy bugs should be isolated until free of insects. The insects can be removed by washing the plant with mild soapy water or by wiping the leaves with alcohol applied with a cue tip. Plants with scale insects should be isolated until free of these pests. The insects can be scraped off. If severe do not retain the plant.

There is no way to control or eliminate viruses.

Transplanting

If transplanting, disturb as few roots as possible. Press the soil firmly around the plant. Do not bury the plant too deeply – use the same soil line that it presently has. Leave a half inch space from the top of the pot to your soil line for watering.

Soil

Use a porous soil. For example, use four parts of high quality soil mix that is high in nutrients such as peat moss or leaf mold, amended with two parts perlite or pumice. The epiphytic cacti prefer a soil that is slightly acidic, and the liberal use of peat moss will provide this slight acidity.This is a great soil mix for your Christmas Cactus. If you can find a pre-packaged cactus soil mix, feel free to use it. If you should use clay pots, remember that they dry out faster and will need watering more often.

1 Place sterile container onto a work surface. The used pot or container will need to be cleaned thoroughly with a solution of bleach and water. Wipe out a new pot with the same solution to be sure there are no contaminants that will infest or kill the plant.

2 Choose commercial planting soil or mix your own. Combine two parts peat moss, one part garden soil with one part sterile sand and mix thoroughly. Place some potting soil in the bottom of the pot.

3 Gently pull the cactus from the old container and place it on a piece of newspaper.

4 Hold the cactus over the pot at the same height that it was sitting in the old container. Gently drop potting mixture around the sides of the cactus roots.

5 Let go of the plant when the soil holds it freely. Add a small amount of soil to firmly secure the plant in place.

Tips & Warnings

Transplanting the cactus will shock the plant. Keep it in the same location and at the same temperature and allow it to recover.

Recommended Species

Christmas Cactus (S. x buckleyii), Thanksgiving Cactus (S. truncata), and Easter Cactus (S. gaertneri) are readily available. Other hybrids have been created by early breeders who crossed Schlumbergera truncata with Schlumbergera russelliana.

Tips/Special Considerations

Positioning: In June you can move the plants outdoors, into a shaded or semi-shaded position. Hanging in a tree is ideal. Keep away from slugs.

Bringing on flowers: The end of the summer is the time to start inducing flower buds for the coming holiday. In early September stop fertilizing until flowering is finished. Cool outdoor nights are beneficial, though not critical, for bud set. Bud set is influenced by hours of darkness. Once the longer nights arrive after the fall equinox in the third week of September, the plants must have total darkness every night for at least three weeks (provide 12 hours of darkness). Outdoor street lights or porch lights can inhibit bud set.

Bud drop: Bud drop can occur for a variety of reasons. When you move plants indoors try not to shock them with drastic changes in light or temperature. Christmas cacti are infamous for dropping their buds when brought indoors. The cause is usually a change in temperature thanks to the proximity of a fireplace, radiator or hot air vent.

Ethylene gas can also be a problem. Keep blooms away from ripening fruit.

Try to keep the soil evenly moist, because sudden dryness of the soil may cause buds to drop. A change in orientation, once the buds are set, may also result in bud drop. Try not to move the plants at that time.



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