Potting Soil for Dendrobiums
Dendrobiums are one of the most common varieties of orchids that lovers of these tropical flowers grow and cherish. About 1200 species of dendrobiums exist, and with the proper lighting, temperature, humidity, fertilizer and potting medium, they are easier to grow than many people might imagine. Once or twice each year, a healthy dendrobium will send up one or more flower spikes, each containing numerous flowers in shades of lavender, white, yellow or red.
Dendrobiums, as well as many other types of orchids, have lived on Earth for many millennia. Fossil records from New Zealand show that this orchid lived as far back in history as the early Miocene period, which is included in the Cenozoic and occurred from 65 million to 1.8 million years ago, according to the University of California at Berkeley. The first hybrid dendrobium orchid was developed in Europe in 1864. By the end of the 19th century, their popularity had grown and a reported 66 hybrid species existed, according to the book “Dendrobium and Its Relatives,” by Lavarack et al.
Dendrobiums Do Not Like Soil
The website Orchids.org emphatically warns that dendrobiums and other orchid species “will not grow in regular potting soil.” They are a type of epiphyte, which is a plant that needs another plant as its host. Epiphyte means “upon the leaf.” They are also sometimes called air plants. The purpose of any type of planting medium is to help hold the orchid upright and to provide it with some moisture. Planting a dendrobium in standard potting soil can kill it.
Buying a Good Dendrobium Potting Material
Special potting mixes for orchids are available for sale. Miracle Gro makes an orchid potting mix that contains composted bark and peat moss: it also contains a slow release plant food that is said to help your dendrobium grow large and produce the maximum number of blooms. Other brands of orchid potting mix include Fafard Pro, Schultz, Pro Mix and Tindara. All of these products contain bark from various trees and some contain charcoal and other ingredients designed to make dendrobiums grow well.
Making Your Own Potting Medium
Do-it-yourself types can easily put together an orchid potting mix of their own. The website Orchids.org lists the following materials as appropriate components of an orchid mix: New Zealand sphagnum moss, peat moss, fir bark chips, redwood bark chips, tree fern fiber, coconut fiber, perlite, granular charcoal, cork and rockwool. The site also recommends using smaller pieces of each material if you want better water retention and larger pieces if you want your medium to drain faster. Experienced orchid growers usually use a combination of media and particle sizes.
Troubleshooting and Saving Sick Dendrobiums
If you inherit a dendrobium that is potted in standard potting soil, transplant it as soon as possible to an orchid potting mix containing bark and other materials. Orchid potting media typically breaks down and fails to drain water after two to three years, after which time a dendrobium or other orchid can begin to show signs of stress, fewer flowers and generally decreased vigor due to root rot and other problems. Repot your dendrobium at the start of its active growing season, usually in spring.
- University of California, Berkeley: The Miocene Epoch
- Dendrobium and Its Relatives; Peter S. Lavarack; 2000, p. 98
- Scotts Company: Miracle Gro Orchid Potting Mix
- Orchids.org: Orchid Culture