WHERE NOT TO PLACE CACTUS PLANTS

When I visited a friend of mine recently, I saw these cactus plants placed near the main door of her neighbour's house.  As far as I know, this is not good as cactus plants have spiky or sharp energy, so feng shui-wise they are not recommended to be placed near the main door of the house, let alone inside the house. They are used, however, as a subtle feng shui cure for protection near the main gate or outside the perimeters of the house. If placed just outside the entrance to the house or inside, the sharp spiky leaves of these plants cause "Sha Chi" or Killing Energy.