Schlumbergera truncata, also known as Christmas cactus, Thanksgiving cactus, or crab cactus, is a beloved house plant. It is often kept in families and passed down through generations as an heirloom houseplant. It’s a hardy epiphytic succulent in its natural environment, tropical forests of south-eastern Brazil.
Schlumbergera truncata is not a difficult houseplant to grow, but it does have a few special needs to grow well and bloom in the winter.
We’ll explain how to care for your Christmas cactus and the best ways to water, fertilize, and propagate it so you too can enjoy it for years to come.
What you will need to follow this tutorial
You want to take care of your Thanksgiving cactus so it is healthy and thrives. You’ll need a few things for that:
- Your Schlumbergera truncata
- Watering can and spray mister bottle
- Rich potting soil
- Pot with good drainage
- 20-20-20 plant food and magnesium sulfate
- a space with bright indirect lighting
- a pair of sharp clippers or scissors
Schlumbergera Varieties and Hybrids
Christmas and Thanksgiving cacti are both in the Schlumbergera genus. They are short day cacti, needing long periods of cool temperatures and darkness to bloom. They need six weeks of 12 hours a day in cool, dim conditions to set flower buds. So if your schlumbergera isn’t blooming in winter, it’s probably getting too much light in a very warm space.
Christmas cactus and Thanksgiving cactus are two separate species in the same genus Schlumbergera. They are very similar but have different leaf structures. Schlumbergera truncata is commonly called Christmas cactus but is actually Thanksgiving cactus. The actual Christmas cactus is Schlumbergera bridgesii. The two are often just called Christmas cactus in the retail trade.
Schlumbergera truncata, Thanksgiving cactus, has clawed leaf edges and is sometimes called Crab cactus because of this. Schlumbergera bridgesii, Christmas cactus, has notched leaf edges which are not as pointed. Both have tubular, brightly colored flowers in shades of red, coral, peach, pink, purple, and white.
The plants in the Schlumbergera genus are leafless cacti with stem segments call cladodes. Some are flattened and some are rounded. The flowers are tubular and pollinated by hummingbirds in their native habitats. They consist of a central floral tube surrounded by petals and sepals, and have numerous stamens.
Is Schlumbergera an Indoor Plant?
Schlumbergera is a tropical epiphyte in its native habitat, growing in the canopies of trees. It was cultivated in the 1800s in Europe in greenhouses, and has been a cherished houseplant ever since, beloved for its winter blooms. It’s grown in homes and greenhouses and for retail sale.
Cultivating Schlumbergera truncata
Step 1 - Watering
Thanksgiving cactus is a tropical succulent and doesn’t tolerate dry soil or environment. It needs regular watering but not overwatering, so don’t waterlog the soil. If you overwater your Thanksgiving cactus, the leaves will develop spots and fall off.
Keep a pebble tray with water nearby or a humidifier, and mist the plant weekly with a spray bottle. Let the top inch or so of soil dry out between watering but not the entire pot of soil. Once or twice weekly is enough. Keep a watering log to write down the date and time you water so you are sure not to overwater.
Step 2 - Soil
Your Thanksgiving cactus needs rich but sandy soil with lots of organic matter. Regular potting soil with added organic matter like compost will let it grow ideally. You can have a regular supply of organic matter with a home composter like Lomi. Some added peat moss or perlite to lighten the soil will also help. The plant likes to be potbound, so don’t put it into an overly large container.
Step 3 - Light and Temperature
Schlumbergera truncata needs bright indirect light and normal indoor temperatures most of the time. But for winter flowering, it needs nighttime temperatures between 50 and 55 degrees to trigger blooming for the holidays.
A month or so before Christmas, put your plant in a completely dark space for 12 hours each night, with low temps. If you don’t want to be moving the plant daily, you can place a box over it at night instead. Water less during this time as well.
Keep the plant in the 50 to 55 degree temperatures during blooming and don’t cause any extreme light or temperature changes. That will make the buds drop and affect blooming.
Step 4 - Fertilizing
No need to fertilize until after the plant has finished flowering in the winter. Then, at the end of winter, start monthly fertilizing when you see new growth. Lowe’s recommends using a 20-20-20 or 10-10-10 plant food diluted to 50 percent strength, and a monthly application of magnesium sulfate solution. Use one teaspoon of magnesium sulfate to one gallon of water, and apply in a different week than the fertilizer, not together.
A plant food formulated for succulents will work well also for spring fertilizing.
Step 5 – Propagation
Cuttings
Propagating Thanksgiving cactus is fun and easy. You can grow more plants for yourself or to give as gifts to others. After the plant is done blooming, take a cutting of two or three segments from the stem tip. Let the cutting dry for at least a few hours or a day or so before planting to avoid any stem rot.
Prepare a small pot with a moist soil and sand mix, and stick the cut end of the stem into the soil about a quarter of its length. Put the pot in a well-lit area but not in direct sunlight. Water only slightly at first, for the first two or three weeks but don’t let it dry out completely. Then you should start to see new growth.
Repotting
Once the new cutting has rooted and started new growth, you can transplant it to a slightly bigger pot with loose sandy potting soil. Water and fertilize lightly at this time, and move the plant into more light but still not direct sunlight. You can water regularly, and it’s a good idea to keep the pot on a pebble tray with water to keep the surrounding area humid.
Flowering
Follow the same instructions as above to trigger blooms in late autumn, early winter, and your young Thanksgiving cactus will flower even though it’s small still.
Step 6 – Troubleshooting Thanksgiving Cactus
Remember, your Thanksgiving cactus is a tropical succulent. It needs humidity, but not waterlogged soil. It has special light needs to bloom in winter, which is why it’s known and beloved.
Follow these tips to avoid problems with your Schlumbergera:
- Pay attention to watering. Too much water in the soil will lead to stem and root rot and eventually, plant death. Letting the soil dry out too much for too long will cause wilting and plant death as well. Keep a watering log to write down the date and time and how much you water, and use a moisture meter to accurately gauge how moist or dry the soil really is for best results.
- The amount of light available to your Thanksgiving cactus is important, all year and in the winter months. Bright indirect light is needed normally, and the proper light/dark schedule in the fall is needed for winter blooming. Avoid placing your plant in direct sunlight.
- Make sure your Schlumbergera is not near direct heat sources or vents where it will get stressed.
- Watch for signs of insect pest, such as tiny white or black flies, spider mites, scale, or rust, and treat the plant as soon as you see them. Neem oil, soapy water spray, and isolation will eliminate most pests.
- Be careful not to over-fertilize, which will stress the plant and eventually kill it. Only fertilize after winter blooming is done and new spring growth is showing.
Consider Growing Schlumbergera
Schlumbergera is a beautiful and beloved houseplant adapted from epiphytes from the Brazilian tropical forests. Many people see them as a welcome gift of flowers in winter when it’s cold and snowy outside, with shorter days. Many families have Thanksgiving and Christmas cacti that have come down to them from grand parents, great grand parents, or other relatives.
With a little attention to their care and needs, anyone can keep a Thanksgiving or Christmas cactus for some winter cheer and perhaps to start a family heirloom plant to pass on to future generations.
Please share this tutorial if you liked it, and remember, the Lomi home composter makes a great addition to any home that has houseplants.