Popular and FUN! Full sun is required for most succulents and all cacti. Allow to dry well in between waterings. For succulents - if the soil is dry, but the leaves are firm, the plant is not ready for water. If the leaves are flexible or have some give to them, the plant can be watered well. Succulents and cacti have very shallow root systems, so many can be planted in one pot without worrying about overcrowding.