You should water indoor cactus plants every 2-4 weeks in summer and every 4-6 weeks in winter. The soak-and-dry method works best for these desert plants. Drench the soil until water runs out the drainage holes. Then wait for the soil to dry before watering again.
I learned this lesson the hard way when I first started growing cacti. My barrel cactus got watered every week because I treated it like my other houseplants. Within two months the base turned soft and mushy from root rot. That mistake taught me that cacti play by different rules than most plants in your home.
The right cactus watering schedule depends on where your plant sits and what time of year it is. Cacti near sunny windows in warm rooms dry out faster than those tucked in cooler corners. A small pot in bright light might need water every two weeks. A large pot in dim conditions could go a full month between drinks without any trouble at all.
Cacti store water in their thick stems using special tissue that holds moisture for weeks at a time. This adaptation lets them survive long dry spells in their native deserts. When you water before the soil dries you fill the air pockets around the roots with water. Without air the roots suffocate and rot-causing fungi move in fast to attack the tissue.
The finger test gives you a foolproof way to know how often water cactus plants in your home. Stick your finger two inches deep into the soil before you even think about watering. If you feel any moisture at all wait another few days. Test again until the soil feels bone dry all the way down before you add water.
Watch your cactus for signs that tell you whether your timing is off. An overwatered cactus turns yellow or brown at the base and feels soft when you press it. The damage often shows up weeks after the excess water first hit the roots. An underwatered cactus looks shriveled with skin that pulls away from the ribs. This fixes itself fast once you give it a good drink.
My neighbor kept a saguaro in her kitchen and watered it every Sunday for years. The plant looked fine until one day the whole thing toppled over. The inside had turned to mush from constant moisture while the skin hid the damage. She could have saved it with less water and more time between drinks.
Your indoor cactus watering routine should shift with the seasons because cacti slow their growth in winter. During the cold months most cacti enter a dormant phase where they barely use any water. Cut back to watering once every four to six weeks from November through February. When spring arrives and you see new growth at the tips you can return to your summer schedule.
Humidity in your home affects watering more than most people realize. Dry winter air from heating systems pulls moisture from soil faster than humid summer air. A cactus in a bathroom with 50% humidity needs water less often than one near a heat vent. Let the soil tell you when your cactus needs a drink instead of marking dates on the calendar.
Terra cotta pots dry out faster than plastic or ceramic containers. The porous clay wicks moisture away from the soil and releases it into the air. This makes terra cotta a great choice for cacti because it helps prevent overwatering. Plastic pots hold moisture much longer so you need to wait more time between waterings with those.
Read the full article: 7 Essential Tips: How to Care for Cactus
