Cacti are succulent plants with a unique and attractive appearance, making them a popular choice for indoor gardeners. They’re relatively low maintenance and flourish in warm and dry conditions, making them ideal for indoor environments. However, they still require adequate sunlight and occasional watering to thrive.
With nearly 2,000 species of cacti found worldwide, it’s vital to know which types you’re growing to give them the proper care. Most cacti are native to desert regions throughout the Americas; however, a few varieties grow in tropical and subtropical areas. Keep reading to find out how often you should water your indoor cacti!
How Often to Water
Proper watering is one of the most critical factors for successfully growing cacti indoors. In general, indoor cacti only need occasional watering. However, their moisture needs depend on the species, the season, and growing conditions, such as temperature, humidity, the size of the pot, and the amount of sunlight the cactus receives.
It’s essential to avoid overwatering cacti, as they are highly susceptible to root rot if the soil stays wet for too long or doesn’t drain well. Check the soil regularly and water only as needed.
Watering Desert Cacti
Most cacti are native to arid desert climates where they only receive occasional rainfall. These plants have adapted to retain moisture for long periods in their fleshy stems. They also have shallow root systems that are thin, fibrous, and widespread to absorb moisture from the soil surface. Desert cacti grow best in sandy, well-draining soil and prefer ambient humidity of 30 percent or less.
As such, during the spring and summer, when the plants are in their most active growth period, water desert cacti when the top inch of soil is dry. The frequency with which you water depends on humidity levels in your house; the drier your home, the more often you need to water. Bottom watering your cacti ensures they get a good soak but remember to drain off excess water. Never leave your cacti standing in water.
Cacti go dormant in winter when temperatures are cooler and daylight hours are shorter. During this time, they need less water — just enough to keep them from shriveling. Generally, reduce the frequency and amount of water by half in the winter, allowing the soil to dry out between watering.
Examples of desert cacti include:
- Star cactus (Astrophytum ornatum)
- Sea urchin cactus (Astrophytum asterias)
- Golden barrel cactus (Echinocactus grusonii)
- Candy barrel cactus (Ferocactus wislizeni)
- Devil’s tongue cactus (Ferocactus latispinus)
- Bunny ears cactus (Opuntia microdasys)
- Rainbow cactus (Echinocereus rigidissimus v. rubrispinus)
- Pincushion cactus (Mammillaria elegans)
Watering Tropical Cacti
There are a few tropical cactus varieties. Most of which have broad, flat stems and few-to-no spines. They produce showy displays of large, colorful flowers more often than their desert counterparts.
In contrast to desert cacti, tropical varieties require more water and higher humidity levels (about 50 percent). Occasionally misting them is beneficial, especially if you live in a dry climate. However, they shouldn’t become waterlogged and grow best in well-draining soil rich in organic matter.
Avoid letting tropical cacti dry out completely between watering, especially during the spring and summer when the plants are most active. When you water, thoroughly saturate the soil until water begins running out of the drain hole at the bottom of the pot. Be sure to empty the drainage tray afterward. It’s best to keep the soil consistently moist and have a similar consistency to a wrung-out sponge.
To encourage flowering, cut back on moisture and allow the top 1/2 inch of soil to dry out between watering during the pre-flowering stage. Once the flower buds form, increase watering to keep the soil evenly saturated. After the plant finishes flowering, reduce watering by half for the next three to six weeks, keeping the soil just barely damp.
Examples of tropical cacti include:
- Christmas cactus (Schlumbergera truncata)
- Thanksgiving cactus (Schlumbergera x bridgesii)
- Easter cactus (Rhipsalidopsis species)
- Orchid cactus (Epiphyllum species)
Signs of Overwatering and Underwatering
Overwatering is one of the most common problems when growing cacti indoors. If the soil stays wet for too long or the plant sits in standing water, the root system cannot absorb enough oxygen or nutrients and suffocates in the waterlogged soil.
If your indoor cactus gets too much water, it will appear puckered and feel mushy. Since these plants primarily store moisture in their stems, the cell walls rupture when they receive too much water. They may also become floppy and turn yellow, brown, or black, especially near the plant’s base.
Another symptom of overwatering is root rot. To check on your cactus’s root system, gently remove it from the pot and look for any black or brown roots. They may seem slimy, and the soil will likely have a sour, rotted smell. If the problem isn’t too severe, remove as much of the diseased soil as possible, cut off the rotted roots, let it callus over, and then repot your cactus in fresh soil. Allow it to dry out for several days before giving it more water.
On the other hand, too little water is also a problem. The stems begin to shrivel and turn brown, usually from the bottom of the plant upwards. They often feel brittle and appear calloused.
Cacti make fantastic, low-maintenance houseplants and will live for many years with the proper care. Correctly watering your indoor cacti is critical to keeping them healthy and thriving. It’s helpful to know which type of cactus you’re growing so you’re able to care for it properly.
Do cacti prickle your fancy? Please share your thoughts on these spiny succulents in the comments below!