Holiday Cacti*, particularly Thanksgiving and Christmas Cacti, are amazing, beautiful, and very common (or at least in the US). You see them in all the garden stores around the holidays because they're one of the few show-stopping plants that bloom in Nov-Dec and which grow easily indoors. Unfortunately, many are mislabeled, and most are actually Thanksgiving Cactus (Schlumbergera truncata) rather than Christmas Cactus (Schlumbergera x buckleyi; How to Tell the Difference). However, you can pick them up after Christmas for nickels and dimes and propagate them till your house is covered in them. Three segments is enough to start a whole new plant which makes them an excellent candidate for doing a large planting VERY inexpensively.
Last year I picked up more than a dozen pots of Thanksgiving Cactus for about $7 which was outrageously cheap. I grew them all year giving them as much outside time as possible, so they were outside from roughly April till early November here in Central Texas.
Schlumbergera are epiphytic cacti and thrive in shade, humidity, and quick-draining soil. Wait, what? Humidity and quick-draining soil? Despite what some sources say, they do not like water-retaining soils, and I have the rotten plants to show for it. They are in the Cactaceae family after all. They come from tropical jungles and grow in the trees much like epiphytic orchids, and also like orchids, they like a coarse "soil" and humidity. Their roots will rot easily if you give them a potting soil rich in compost and peat moss.
Towards the middle of October, my Thanksgiving Cacti started to bud as the daylight hours shortened and my watering regime lessened. I submitted this particular planting to a garden show competition and got a Green Thumb (the equivalent of an A+). I might have taken a "Best of" had it been fully in bloom rather than just budding. Of course, it started blooming a week after the show, and they've been blooming and setting new buds ever since. For the rest of the year, they look like a pretty green lawn of non-threatening cacti which is very attractive in my opinion.
This Instructable shows how to mix an organic cactus potting soil, repot a Thanksgiving/Christmas Cactus, take advantage of after-Christmas plant sales, and prepare an extravagant planting for next year. I'm doing this on a smaller scale as I already have a huge planting and have spent the past year experimenting with the plants. However, once you know how to prep the pot, mix the potting soil, and separate the plants, you can easily create a huge planting of them. Like most inexpensive, DIY gardening projects, you have to wait to reap the benefits, but you will have something spectacular in the end. I worked on a single planting for a year, and I don't regret it. I have other plantings that will take decades. Consider this "quick" when it comes to plants and gardening in general.
Note: I say "cacti" rather than "cactuses" out of personal preference. Spelling nazis can argue the finer points of which is correct.
Note: I am using plants in this Instructable that are budding/blooming which is something you do not want to do. The blooms and buds are very sensitive to movement and will drop off easily. Wait until the plants are done blooming before repotting so you can enjoy them for as long as they last - there will be plenty of time to see them without the blooms/buds.
Note: As with many gardening how-to's, there's going to be disagreement. Many gardeners, including myself, are reluctant to be explicit in how to care for plants because it's more art than science, but if it weren't for gardeners willing to be explicit, I never would have tried because it would have required too much mysterious gardening voodoo. In the end, you're going to develop a sense of how to best care for a plant by feeling it out and trying lots of different things, and depending on how you garden, you might have to adjust some of the things I suggest.
Step 1: Mix Cactus Potting Soil
1 Part Builder Sand
1 Part Pea Gravel or Perlite
1-2 Parts Compost (preferably your own)
Take a container (tin can in my case) and fill with sand. Pour into a large bucket. Repeat for the gravel and compost using the same container.
Note: You will need enough to fill the pot.
Step 2: Potting Materials
-Holiday Cactus (this variety is called 'Beach Dancer') - Grab these up after Christmas
-Piece of Thin Paper (or a piece of panty hose)
-Sand (shown in the tin can)
Note: If you want to replicate the large planting in the intro, you will need a galvanized steel feeding dish into which you'll have to drill drainage holes. Mine is Behrens, and I picked it up at Home Depot and used a drill bit capable of drilling through metal. Use a file to grind down the rough edges.
Step 3: Cover Drainage Hole
Cover drainage hole with a thin piece of paper (or piece of panty hose)
Step 4: Add Initial Soil
Add a bit of potting soil and pat down.
Place the potted cacti in the pot to estimate how much you need.
Keep adding until you have the appropriate amount with roughly 1-2" of headroom.
Step 5: Separate Plants
Gently separate the plants in the pot. You will be able to feel points where they will release from one another. Keep coaxing until you have each plant separated.
Step 6: Pot Up
Start pressing and filling soil around each plant. You may have to add some soil underneath each one depending on how much of the original potting soil you lost. You want each plant to be snug in the potting soil.
Continue until each plant is potted, all gaps are filled, and the soil is firm.
Step 7: Finish
Top the potting soil with fresh sand. This will help keep the gnats away and make the pot a little prettier.
Make a small hole in the paper covering the drainage hole with the point of a pen. Skip this step if you use panty hose.
Step 8: Maintenance
THESE ARE VERY GENERAL SUGGESTIONS!!
Gardening is more art than science.
How to Water:
Soak the soil completely with each watering.
Allow the soil to completely dry between watering. Shriveling is a sure sign it's time to water.
Mist regularly or keep a small tray of water nearby if in a low-humidity environment (e.g., indoors).
How to Fertilize after First Year:
Fertilize with a fish emulsion twice a year following the directions on the bottle.
How Much Sunlight:
Keep in the shade if outdoors (min temp 45F).
Keep near a sunny window but out of direct sunlight if indoors.
How to Remove Hard Water Spots:
Mist HEAVILY with distilled water.