Leaching
is the process of losing nutrients from the soil in a container due to the water dissolving them, so any water dripping from the container will carry some nutrients from the pot.

Nutrients are also leached into the walls of the pot itself, if it is porous. If you use clay or terra-cotta pots, you may see white or gray stains that are hard to remove. These are evidence of leaching.

If the nutrients are not replaced, over months this loss can be enough to cause yellowing of the foliage or a generally poor looking plant. A natural Tea can be used to combat leaching.

Place a saucer under potted plants to reclaim its dissolved nutrients. An hour after watering, return the leachate to the plant. Do not apply it to a different plant, since this may spread diseases among your plants. The donor plant may be immune to diseases that may be lethal to others.