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Schlumbergera

Description

 

Christmas Cactus

Christmas Cactus

This is a cactus native to the tropical moist forests of coastal Brazil which is very different in conditions from the desert cactus that commonly comes to mind.  They grow on trees and rocks in shady places.  Each arching stem is made up of many oblong, flat segments of a bright green from whose tips hang many-petaled flowers.  The flowers coincide with the holidays, each flower lasting only a few days but new blooms emerge from the tips of the flat segmented stems over a period of several weeks.  Red is the original species color but new hybrids include white, pink, violet, orange and even yellow.  This plant does take some attention but with care can become an heirloom lasting for generations.

 

Light and Temperature

 

Indirect light and cool temperatures are ideal for the Christmas cactus.  Summer temperatures outside are fine and you can leave it outdoors, in a shady location, until nighttime temperatures fall into the low 50’sF (10°C).  Be very careful that it does not freeze.  When you bring it in for the winter be sure to put it into a cool room.  55°F (12°C) is a good winter nighttime temperature for this plant and 65°F (18°C) during the daylight hours.  If you take it from 50°F (10°C) outside and bring it into 70° (21°C) indoors you can expect some segment drop.  This is normal.  You may not keep your home this cool and your plant will do fine – just keep it as cool as you can.  Close to the glass of a northern or eastern exposure for the coolness and indirect light would be good.  A western facing window on a sunny day may be too hot.  If you have only a western or southern window be sure it is filtered and not too warm.  This plant does not like drafts so keep it away from forced air heating registers and outer doors.

 

Watering

 

Water when the soil is dry, about 1” (2.5cm) down, from early spring through early fall using room temperature water.  Give enough water so it runs through the drainage hole in the bottom of the pot.  Never let the pot sit in water.   Gradually cut back on the watering in September until you are waiting to water until the pot is dry 2/3’s down.  This transitions will take about a month and is your plants first rest period.  After this first month you will pick up slowly on the watering to give the plant energy for the setting of buds.  Do not water until the water runs through.  Only moisten the top few inches.  When the bloom time is over and the flowers begin to fall off, (or mid-winter if your plant did not flower), the plant needs a definite second rest period so cut back on the watering again to 2/3’s dry until spring.  As they are tropical they will appreciate a tray of pebbles to sit on that is filled half way with water to provide humidity.

 

Medium

 

A mix of 2 parts coarse sand,1 part perlite (or vermiculite), 1 part sphagnum peat (or coir) and 1 part humus (or compost) would be a good mix for this plant.  To every cubic foot add 2 oz. of dolomite limestone.  This is a little richer than your basic succulent mix with the addition of the loam and the limestone raises the ph.  If you purchase a commercial potting soil check to be sure they have added the limestone as your Christmas cactus likes a more alkaline medium.

 

Feeding

 

Feed your plant with a diluted fertilizer like 10-10-10, every 2 weeks or so when you regularly water, from spring through early fall.  Christmas Cactus are heavy feeders for the flowering season and if you have it you can use a ¼ dilution of a fertilizer labeled 5-10-10, every time you water, from early fall through until the last flower bud has opened.  You do not feed your plant from the time of the last opening flower until spring.

 

Flowers

 

Christmas Cactus flowers

Christmas Cactus flowers

As the October days (in the Northern Hemisphere) grow shorter and the nights get cooler the plant is signaled to begin the formation of flower buds.  About 3 months before you want flowers you must cut back on the watering so your plant is dry about 2/3’s down before watering, using room temperature water, and by moistening only the top 2-3”, not letting the water run through as you did in the summer.  This is the first rest period.

You also need to simulate the total darkness of the forest from sunset to sunrise. Christmas cactus must get no artificial light through the night.  If the nights are still above 50° (10°C) and your plant is outside you can provide the necessary total darkness (remember street lights or porch lights, etc.) with a cardboard box over the top with something heavy on top to keep it from blowing away.   When your plant is indoors you can cover it, put it into an unused bathroom – covering the windows, or into a closet for the night.

Keeping your plant cool, 50-60°F (10-15°C), will help the formation of flower buds.  The closer to 50°F (10°C) the better.  The warmer room usually means fewer blossoms.  The biggest danger I have found is forgetting it’s hiding from the night lights (and me) and forgetting to give it the bright light it does need through the daylight hours.  Not enough light during the day will cause those flower buds you’re working so hard to get to fall off.  Be sure to get into a good routine each morning; give it light, rotate the plant ¼ turn for even flower coverage, and check for water.

Following this regimen should give you a brilliant show for the holidays.

When you see flower buds forming, about 1 month into your routine, increase the water slowly, moistening the top few inches only when dry about 1”(2.5cm) down.  You can stop the dark nights when you see several flowers and lots of buds.  This takes about 6-8 weeks.  It could use a humidity tray at this time.  Adding humidity will help the plant retain the flower buds until they open.

When flowering you should have no problems if you move it into a slightly warmer location for the show.  You may get some flowers without all this fuss but with it you will have a magnificent display.  After flowering it will need a second period of rest so cut back on the watering again until dry 2/3’s down until spring.  You can pinch off the flowers that are done to encourage future branching.

 

Pests and Problems

 

White or transparent spots on the segments may be a sign of overwatering.

Root rot will occur if too much water.

Yellowing of the segments may mean you need to add limestone to raise the ph of your soil, especially if your soil in mainly peat based.  Christmas cactus like a slightly more alkaline soil.

Christmas cactus may attract aphids, spider mites or mealybugs.

You may get fungus gnats in the soil if you are keeping it too moist.

 

Re-potting

 

The wider the pot the bigger the plant but too big a pot and your plant may not flower.  To produce flowers they prefer to be pot-bound.  A good time to repot is after flowering and about a month of rest.  Perhaps every 3 years in February, March or April.  Use a well aerated medium as described above. Do not fertilize for 2-3 months after repotting.  There will be enough nutrients in a good soil mix.

 

Propagation

 

Christmas cactus are easy to propagate.  Just cut a few pieces with at least 2 joined segments using a clean, sharp knife and set them out to dry.  The following day put them in a soilless medium to get them started.  Once you see growth begin you will move the new little plants to the mix described above.  If you have a nice mix for cactus and succulents you can use this also as it should not have too much in the way of nutrients that would burn the new roots forming.

 

Tips

 

Your Christmas cactus will benefit from a vacation outdoors in the milder summer months.  As with any houseplant, it will dry out more quickly due to the breezes but will dry out less quickly if the humidity is high and you will adjust the watering schedule accordingly.

One day when the flowers are spent and your plant needs a regular watering you can place it in the shower and gently rinse it off with tepid water.  This will clean any dust that may have accumulated through the time indoors.  This is always a good idea before bring the plant inside for the winter too as explained in the blog article.  After a shower do not put it into direct sun but into a well-ventilated place for it to dry off.

 

Varieties

 

Schlumbergera bridgesii – Christmas cactus

Schlumbergera truncatus – Thanksgiving cactus or crab cactus due to the pointed claw-like edges at the tips of the segments.  It has white, nearly any shade of pink or red, or bicolored flowers.

Schlumbergera russelliana – Shrimp cactus – a dwarf plant with 2 small flowers at the end of each flowering segment and is spring blooming

Rhipsalidopsis gaertneri – Easter cactus – blooms in spring – requires a bit warmer temperature than the Christmas cactus

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