Episode 84: Forest cacti part one: Easter, Christmas and Thanksgiving cacti
Christmas cacti defy the stereotype of the spiny desert plant: they grow in trees like leafy chandeliers in the jungly woodlands of South America. Along with their close relatives the Easter and Thanksgiving cacti, these members of Rhipsalidae tribe have secured a place as one of the most enduringly popular houseplants of the last 100 years: they sell in their millions, ending up as impulse buys in supermarket shoppers’ trollies as well as carefully raised specimens bought from specialist nurseries.
This week’s guest, Mark Preston, has been growing Rhipsalidae for years; he is a member of the British Cactus and Succulent Society and regularly gives talks to group meetings about these plants. In this episode, we discuss Christmas, Easter and Thanksgiving cacti, and next week Mark will be back to cover the other members of the Rhipsalidae: Hatiora, Lepismium and Rhipsalis. Check out the notes and images below as you listen to the show…
Cactus confusion… how to know if you have a Christmas, Easter or Thanksgiving cactus
If you’re confused about the differences between the various ‘holiday’ cacti, don’t worry - you are not alone! That’s due at least in part to the fact that there has been a great deal of interbreeding between different species in the last 100+ years.
Mark explains that two Schlumbergera species were imported into the UK from Brazil in the 1800s - first came Schlumbergera truncata, an autumn-flowering cactus. Then came the closely-related species Schlumbergera russelliana which flowers in spring.
In the 1840s, breeders began to cross these Schlumbergeras together to produce the first of the Christmas cactus hybrids so popular today. The timing of the flowering of your Schlumbergera will depend on its breeding: hence the so-called thanksgiving cactus probably contains more S. truncata genes and will flower before Christmas.
Easter cactus is a hybrid of two species of Rhipsalidopsis* - a small one, Rhipsalidopsis rosea, and R. gaertneri, which is larger and has orange flowers. (These were reclassified as Hatiora a few years ago although they have now been reinstated as Rhipsalidopsis. I know - it’s confusing!).
And a final note: there are other epiphytic cacti that aren’t members of Rhipsalidae tribe: that’s because epiphytic cacti aren’t an official family in botanical terms. Examples include the rat’s tail cactus, aka Disocactus, and the genus Epiphyllum, which are both part of the Hylocereeae tribe of epiphytic cacti. And there are are lithophytic cacti that grow on rocks, such as monkey’s tail, Cleistocactus winteri subsp. colademononis. We’ll try to cover more of these in another episode! (Intrigued by our talk of ‘stove plants’? Here’s a book published in 1840 that describes some of them.)
Holiday cactus care
If you’ve bought a holiday cactus home from the shop only to find it has dropped all its buds, you are not alone! Once a plant is settled in your home, don’t worry about the myths that turning the plant around when it is in bud will cause them to drop off - Mark tried this with a plant with 200 buds and it was fine! However - just-bought plants do have a tendency to drop their buds. This is because plants grown really quickly in ideal conditions in commercial greenhouses are then transported to retailers in poor conditions, and the shock of cold and wind is enough to cause these young plants - barely more than cuttings - to lose their buds. There’s not a lot you can do about this: you could try putting new plants in a clear plastic bag, but then you won’t be able to see the flowers well. Do avoid putting them in draughts, which could cause the buds to drop.
When it comes to potting these plants, remember that in nature they have fairly small rootballs, growing in nooks of trees and living on dead leaves, twigs and moss. They like open organic-based compost kept moist but not sodden. You can make your own mix of chopped bark, coir, perlite, and vermiculite; just make sure it offers a combination of moisture-retentive soil that’s also full of air pockets. Mark has had success growing Schlumbergera russelliana on the outside of hanging porous (non-glazed) terracotta pots secured with nylon fishing line and growing only in moss (pictured above).
Light-wise, think about the places where these plants grow in the wild. They don’t want direct sun, and will cope with surprising amounts of shade. Christmas/Thanksgiving cacti are short day plants - which means their buds appear as the days get shorter, so any artificial light that mimics longer days could affect them by slowing down bud production, but of course this depends on the light source and how close it is for the plant. They like a spell outside in the summer, provided they are not too exposed - hanging from a tree is ideal!
Schlumbergeras and Rhipsalidopsis appreciate a humid environment - try the terracotta technique above, or the usual techniques of gravel trays, grouping plants and locating in more humid rooms, eg the kitchen.
Holiday cactus will survive surprisingly low temperatures - around 55F/12C is acceptable during resting periods.
Getting these cacti to flower again can be a struggle. Try go give them time outside in the summer months and a rest before flowering, when the soil is kept fairly dry. New stem sections appear from April onwards after a winter rest - then there’s two flushes of growth during spring and early summer, and a lull while buds appear during late summer until they start to flower.
Question of the week
Alyson wants to know what to do about her prolific spider plant, Chlorophytum comosum, which is growing lots of baby plants (you can call them spiderettes if you like!) which are in turn producing more babies.
She wants to know how this will end: babies on babies on babies? Well, yes. The spider plant is generous with its stolons, the stems that grow offspring which will then root into the soil to make new plants.
You can either leave these on the plant, snip them off or let them make new plants. One way to do this is to pin a baby plant into a pot of compost next to the parent plant until it roots. You can also snip off a baby and root it in soil. If your spider isn’t producing any babies, it may mean that the plant is concentrating all its energies into developing new roots. Don’t worry, they’ll come!
I’d love to hear your spider plant stories for my Chlorophytum episode: maybe you have a monster plant, or you just can’t keep a spider plant alive? Or perhaps you want to ask me a question about some other plant? Either way, tweet @janeperrone, leave a message on my Facebook page or email firstname.lastname@example.org.
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This week's show featured Roll Jordan Roll by the Joy Drops, An Instrument the Boy Called Happy Day Gorkana by Samuel Corwin and Oh Mallory by Josh Woodward. Ad music is Dill Pickles by the Heftone Banjo Orchestra. All tracks licensed under Creative Commons.