The Stenocereus Pruinosus succulent is also known by its common name of Gray Ghost Organ Pipe. The most common sign of discoloration is caused by either over- or under-watering. A: You can touch your succulent plants, but only if you wish to check for discoloration or signs of pests and diseases. These are signs that your succulent has outgrown its pot. Some succulent aficionados recommend placing a saucer filled with water under the pot. This will allow the roots of the cacti to draw the water up. It can be watered as long as it is not completely dried when it is removed.