Cacti can grow prolifically during the spring and summer, and it's important to water them properly during this growth period. They absorb water rapidly, so be sure to keep the soil slightly moist. Withhold water during the fall and winter when cacti aren't actively growing. Apply only small amounts of water to moisten the soil around the roots, and allow the soil to become dry before you apply additional water. Water every two to three weeks to provide adequate moisture during the no-growth season. For more information, see PlantTalk script #1306, Cactus.
