When in doubt about watering your cacti and succulents, do not water. You can measure the soil moisture by using a moisture meter. Underwater instead of overwater. Never let cacti and succulents sit or stand in water. Check for stem and root rot: if the cactus feels soft and/or has black-brownish spots on the body of the plant, you may be overwatering. If you have a garden bed, you can improve drainage by raising beds, mounting the soil, and building terraces or slopes. Let the soil dry out completely between watering.