When watering from above, the water should be added until some comes out the drainage hole. If the potting medium has dried and pulled away from the sides of the container, the water will run straight through without moistening it. When this happens, leave the container sitting in water until the soil surface is moist, then discard the remaining water as in watering from below. When determining the watering needs of houseplants, it is important to take cues from the plants themselves. If the potting mix feels bone-dry and has shrunken in the pot, it needs water.
Dry media are lighter colored than moist soil mixes and more light weight.
The most reliable way to check for dryness involves feeling the potting medium. If the surface is dry, feel a little deeper. The decision of watering should be based upon the watering needs of the particular plant. This information is for educational purposes only. References to commercial products or trade names does not imply endorsement by MSU Extension or bias against those not mentioned.