QUESTION: Do Christmas cactus like to be rootbound? Someone told me not to repot it because it’s healthy right now. – Forrest D
ANSWER: Christmas cactus grows well with crowded roots, so your friend isn’t totally wrong. Christmas cactus can do ok when it has become rootbound, but you should still repot your holiday cacti every four years, increasing the size of the pot by two inches each time you repot.
Repotting a Christmas cactus can be a challenging operation, as you can easily hurt the plant trying to remove it from its pot when it has become rootbound. The easiest way to get it out without hurting the plant is to break the pot. Clay pots are cheap, so it’s not a big loss, and it makes it much easier to rehome your cactus without damaging it.
Signs that your cactus has become root bound include noticing the soil in your planter growing increasingly hard, seeing the roots growing out of the drainage hole/holes of your pots, or if the stems of your Christmas cactus start to turn yellow or brown (the latter symptom is also sometimes a sign of overwatering, not overcrowding). If you notice these signs, it’s okay to keep your plant in its overcrowded pot for a few more weeks, even months, as it really does enjoy being crowded. But eventually, you will want to repot to give it some more room, and to bring your cactus some newer, more fertile soil in the process.
Use a potting soil that is specially formulated for cactuses and succulents to increase water drainage speed. Put enough new soil in the new, larger replacement planter, so that the top of the root ball will sit approximately one inch deep from the top of the pot. Gently brush off the root ball and remove a good amount of the old soil from the roots and root ball. You may want to moisten or rinse the roots off with water to get the majority of the oil soil off of the roots and root ball.
Next, put your cactus into its new pot and carefully fill in the area around the root ball with the fresh new potting soil that was formulated for desert plants. Remove any yellowing or dried up stems that you notice while repotting. Once the new soil is firmly in place, water your Christmas Cactus deeply and select a shady area to place it in for a few days while it gets adjusted to its new home, new soil, and extra space.
Keep your cacti in a shady spot on the porch or patio during the spring and summer, where they can get lots of fresh air and indirect sunlight. Take a few cuttings every year in the fall if you like, and give them away as gifts once they mature. In the fall, bring them inside and keep them in a dry, darker location away from direct sun. If you can provide a slightly humid indoor environment, your Christmas cacti will do especially well.
When October rolls around, start drying the soil to encourage holiday blooming. In lue of watering once per week, cut down to just providing a light drink once every three weeks. Darkness and dryness are both essential to encouraging holiday blooms. Some gardeners even provide covers, keeping their cacti in the dark for a few weeks in order to encourage their Christmas cacti to flower.