Key Points
Water Christmas cactus only when the top 1 to 2 inches of soil are dry, usually every 1 to 3 weeks.Light, pot size, and humidity all affect watering needs.Use room temperature water, drain excess moisture, and watch for signs of overwatering or underwatering.
The Christmas cactus (Schlumbergera x buckleyi), one of the three types of holiday cacti, provides joy and vibrancy to homes during the festive season. These tropical plants are native to southeastern Brazil; their bright green leaves and pink, purple, or white flowers brighten up any room.
Fortunately, Christmas cacti are easy to grow, and when cared for properly, they’ll bloom just in time for the festive season. Make sure you’re watering them correctly, though—follow these steps for best results.
How Often to Water
Christmas cactus needs to be watered when the topsoil is dry. Check the soil moisture by placing your index finger an inch or so into the soil. You can also use a moisture meter or pick up the plant to feel how heavy it is.
“A great rule of thumb is to water Christmas cacti when the top 1 to 2 inches of soil feels dry, usually every 1 to 3 weeks, depending on conditions,” says Kelly Funk, president & CEO of Jackson & Perkins.
The frequency of the soil drying out is based on many factors, including light, humidity, and temperature in the home. Experts recommend never watering on a fixed schedule—always check the soil moisture first.
Factors to Consider
How often to water a Christmas cactus can vary widely. “As your environmental conditions change with the seasons, this can affect how much or how often you water your plant,” says Justin Hancock, horticulturist at Costa Farms.
Sunlight
Christmas cactus does best with bright, indirect sunlight—it also affects how quickly the soil dries out.
“The more light your plant gets, the more energy it will have to grow and be healthy, and to reduce stress,” says Hancock. “If your plant doesn’t have a lot of bright light, its reduced growth rate might offset the increased evaporation. So you could find your plant needs less water in winter, even though conditions are drier.”
Sometimes, seasonal differences can play a role in how quickly or slowly the soil dries out. “Some people find their holiday cacti dry out a little faster in spring [and] summer than in fall [and]winter, because the days are longer and temperatures are warmer,” he adds.
Container Size
The size of your pot also influences how often you need to water. A smaller or shallower container dries out faster and will require more frequent watering, says Funk. An oversized pot stays wet longer; however, it could also increase the risk of root rot.
Temperature and Humidity
“Average to above-average relative humidity levels over about 45 percent or so are optimal for a holiday cactus,” says Hancock.
However, temperatures can increase and become drier with heaters during the colder months. “Dry air or low-humidity conditions increase the rate of evaporation of moisture from the potting mix, and potentially from the plant’s fleshy stems, too,” he says. “So if you have a spot with lots of bright light in fall [and] winter, then you might find your holiday cactus drinks just as much moisture as it does in the longer days of spring [and] summer.”
How to Water
Fill up your watering can or bottle with tap water, then top water.
“Use room temperature water and water thoroughly until it drains out the bottom,” says Funk. Be careful: Using cold or hot water can shock the roots. If there is excessive water sitting in the saucer, pour it out so the roots don’t sit in it.
Signs of Underwatering
A Christmas cactus that doesn’t receive ample water will usually lose its flair.
“When a holiday cactus gets a little too dry, its fleshy stems may be a duller, less vibrant green color,” says Hancock. “If it continues to stay too dry, then the stems may start to look a little droopy and wrinkled,” he says. If you touch the stems, you may notice that they feel softer than usual.
Signs of Overwatering
Wet, soggy soil is often the first indicator that the plant is overwatered. “If it’s been staying too wet, it may also start to droop,” says Hancock. The stems will feel mushy to the touch instead of pliable.
Stems will begin to turn yellow if overwatering continues. Overwatered plants can also emit a sour smell from the soil, which is often a sign of root rot, says Funk.
To avoid overwatering, observe how long the potting mix stays wet or moist after each watering. “If it still feels wet a week later, then you may be adding too much water at once; reducing the amount of water so the mix dries out faster is the way to go,” he says.
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