20160228A.jpgIf your tap water is very hard, with a pH of 7.5 or higher (your municipality will be able to tell you), it would be wise repot your houseplants twice a year, in spring and early autumn, replacing almost all the potting mix each time. Hard water contains a lot of dissolved mineral salts, salts that are toxic to plant roots when they accumulate… which they will do very quickly in a pot where excess water doesn’t drain away, but remains in the saucer. By repotting twice a year and throwing the old potting mix into the compost, on the other hand, you’ll be cleaning the roots of contaminants, leading to much healthier growth from your plants.

If you can’t repot that often, consider leaching the mix every two months by letting water run through the soil and drain into the sink. Leaching likewise reduces the accumulation of mineral salts. You can find more information on leaching in the text Happy Houseplants Need Leaching.

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

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