Has your Christmas cactus or Thanksgiving cactus dropped leaves that look green and healthy? This is certainly really frustrating, and I have had a lot of people ask me why this is happening, so in this post, I'll go over the most common causes and it's all related to root health.
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Why Your Holiday Cactus is Dropping Leaves
Whether you have a Christmas Cactus, Thanksgiving Cactus, or Easter Cactus, the care is identical (and yes, they are all different plants). And what you see aren't technically leaves, but rather, leaf segments called phylloclades. But for the sake of simplicity, I'll call them leaves in this post.
The main thing that these plants dislike is extremes in growing conditions, especially: inconsistent watering habits, poor drainage, oversized pots that are much too big for their root system, and poor choice in potting soil. Let's get into each of these.
Inconsistent Watering Habits
Holiday cacti, like many plants that are often grown indoors, like stable conditions. While they are true cacti (a jungle version), they can take drying out completely, but they don't like to stay bone dry for too long.
What is worse though is keeping the potting mix too wet for too long. This can easily cause the plants to drop leaves that otherwise look healthy. If your soil is taking too long to dry out, it can be caused by so many factors: not enough light (this is unfortunately very common), the wrong type of potting mix, no drainage holes in the pot, and other factors.
I typically allow the top 1-2 inches of potting mix for any holiday cacti to dry out before watering again. ALWAYS use pots with drainage holes. Ensuring that your plant is immediately in front of a window with good light is crucial as well. Keeping your plant a few feet or more away from any window will not be good for growth or blooming, and it will cause your potting mix to stay wet for much longer. All of this can cause perfectly healthy looking leaves to drop.
After watering, it's important to discard any excess water that has accumulated in your plant's saucer. If you have pots that have saucers that are attached, I find that these types of pots are horrible for drainage and I avoid them for all plants after a few bad experiences with them. I encourage you to avoid those pots as well.
For complete care tips, read my article on christmas cactus care, but let's look at more causes of leaf drop now.
Terracotta pots go a long way in maintaining good root health for any holiday cacti like my Thanksgiving cactus in this photo
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Oversized Pots & deep pots
Holiday cacti have shallow root systems and they prefer to grow in pots where their root systems are a little snug. Using unusually deep pots is problematic because often times, the lower roots will rot due to the excessive volume of soil retaining moisture for longer. Anytime the root system rots, the plants will often respond by dropping leaves.
Whenever you are repotting holiday cacti, use a standard dimension pot or one that is shallower than "normal." As far as the pot diameter goes, a good rule of thumb is to only go up one pot size in diameter if you need to repot and your plant's roots are completely filling up its current pot. For example, if you are currently in a 4 inch diameter pot, only go up to a 6 inch pot. Only go up a pot size if your plant is completely root bound.
When you go up in pot size, the goal is to allow the roots a little more room to grow, but not to have SO much excess potting mix that it stays wet for too long and cause issues with rot. A scenario that is disasterous would be having your plant in insufficient light, poorly draining soil, and an oversized pot. This will surely cause your plant to collapse and drop leaves, or worse.
Pro tip: terracotta pots are wonderful for holiday cacti. They are porous and allow more air to the roots, which is beneficial for any plant, particularly epiphytes. They will dry out faster than other types of pots, so please note that the watering frequency will be higher than plants in plastic pots.
Poor Choice in Potting Mix
This is a big one. Christmas cactus, Thanksgiving Cactus and Easter Cactus are all epiphytes, which means that they grow on trees. They don't grow in soil in the ground, so I never use just any potting soil straight out of the bag. The potting mix, ideally, will have some moisture retention, but with very sharp drainage.
Typically, plant roots will rot not from moisture, but from lack of air/oxygen at the roots. When soil stays wet for too long and the potting medium isn't porous enough to allow air to the roots, the roots will start to suffocate and certain pathogens will attack the roots and you'll get root rot. When that happens, your plants will drop leaf segments.
Choosing your potting mix wisely goes a long way in preventing problems for any of your holiday cacti. Read my article on my recommended potting mixes for christmas cactus and other holiday cacti. A good potting mix is foundational for the health of any plant.
OTHER things to keep in mind about leaf drop
Now, this is a good "problem" but if you have a plant that got really huge over time, it can actually collapse under its own weight. I once had a Christmas cactus that had gotten so big, that an entire branch fell under its own weight. It was hanging in front of a large window and was draping over the pot about 3 feet.
If you only had one or two leaves drop, and then it stopped, I wouldn't worry too much. If it's a continual issue, you may want to re-evaluate your growing conditions and evaluate what I've laid out in this article.
Sometimes if your plant has been in the same pot for many years and the plant is extremely pot bound, it can also cause some minor leaf drop. Refreshing the soil and giving it one size larger pot will help.
