Brown leaf tips, yellowing leaves, and unaccountable wilting of leaves are all signs that salt build-up in the soil is affecting your houseplant’s health. Roots can also be affected by salts in the soil and result in foliage that is wilted even though the soil is moist. The most obvious sign of accumulated salts is a whitish crystal build-up around the lip of a pot or on the top of the soil.
Salts may be present in water, especially “softened” water, and many fertilizers are salt based. As moisture evaporates from the soil, salts are left behind. To help avoid salt build-up in the soil, apply fertilizers at the recommended rate, and water houseplants thoroughly so that water drains from the bottom of the pot. Be sure to discard the water that drains out after watering. Do not allow the plant to stand in the water. If the plant has symptoms of salt build-up, salts can be leached from the soil. In extreme cases the soil may need to be changed and the plant repotted.
To leach out soluble salts, remove and discard the white crust and some of the potting mix from the surface of the root ball. Depending on the size of the plant and root ball, one-half inch to one inch of potting mix can be taken off without harming the plant. Be careful not to damage the roots.
Remove the saucer and place the pot in a sink where water can drain freely. Make sure the pot’s drainage holes are not plugged. Using tepid tap water, rinse the potting mix by filling the pot to the top with water a couple of times. Wait for the potting mix to drain well between rinses.
Scrape excess salts from the outside of the pot, the drainage holes and the saucer. Using warm soapy water, clean the saucer. Rinse and allow to dry.
Replace the potting mix taken from the surface with new mix and water lightly. Water the plant only when the original root ball feels dry to the touch.