By Michelle Wach, horticulturist, Colorado State University
Do Your houseplants have a white crust on the the soil surface? The white crust found on the surface of potting mix in houseplants is a build-up of soluble salts. These salts come from the potting mixed themselves, from fertilizers and even from the water used to irrigate the plants.
Excess soluble salts can cause root damage, which then leads to problems with water uptake. Soluble salts also can cause damage to foliage.
The problem can be improved by removing the crust from the top of the potting mix, scraping excess salt from the outside, around the drainage holes and in the saucer. Remove about 2 inches of the potting mix. Place the plant in a sink or tub where water can drain freely. Using tepid tap water, fill up the pot several times allowing the water to drain out completely. Return plant to the saucer, add new potting soil to fill and water lightly.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010