Professional growers as well as hobbyists have long debated the best materials with which to pot their beloved orchids.
For decades, the potting mediums of choice were osmunda fiber or various bark mixes of redwood, pine or fir. The mixes often contained additional ingredients, such as perlite, charcoal, coconut husk, cork, lava rock or just about anything a grower thought would make the mix better. Nurserymen might consider their formulation to be proprietary.
Preparation of these special blends was no easy task. Perlite tended to float, peat moss sank, and coconut had to be triple-soaked to leech out the salt. Industrial machines were often used to scramble the ingredients thoroughly.
Techniques for repotting varied as much as the formulas. Some mixes performed best when packed tightly, sometimes using wooden rods. Others were moderately or loosely packed. Still others were just poured in. Getting consistent results for each pot was challenging.
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One medium that has had a unique place in the greenhouse for more than 150 years is sphagnum moss. Small seedlings, back-bulbs and weak or sickly plants all need tender loving care. Sphagnum has antiseptic properties that help lower the incidence of rot. In addition, sphagnum offers excellent water retention so delicate roots can develop.
Sphagnum is a genus of mosses containing more than 100 species and is found in bogs throughout the world. These mosses store large quantities of water — approximately 20 times their dry weight — for use during periods of drought. Bogs may be many feet deep with sphagnum on the top and decaying “peat” on the bottom. Moss is a sustainable crop as long as it is allowed to regenerate — typically more than 10 years.
Like many commercial nurseries, we began our business propagating mature Cattleyas, Oncidiums and Phalaenopsis in a bark mix and young or weak plants in sphagnum. Much to our surprise, we noticed that the meager were sometimes outperforming the strong. It wasn’t long before entire greenhouses were converted to sphagnum moss.
Arthur Chadwick is president of Chadwick & Son Orchids Inc. Reach him at 1240 Dorset Road, Powhatan, VA 23139; (804) 598-7560; or by email at info@chadwickorchids.com. Previous columns are on his website, www.chadwickorchids.com.