Fir Bark – Probably the most common orchid media, fir bark is often combined with one or more of the other ingredients to create an orchid "mix". It is commonly available in sizes that range from “fine” for seedlings and Paphs, “medium” for orchids like standard sized Cattleyas and “coarse” for Vandas or large specimen plants. As it ages, fir bark becomes soft and eventually breaks down at which time repotting is needed. Typically fir bark will last for about two years before it begins to age and must be replaced, although we continue to grow Vandas and Dendrobiums for many years without repotting and no problems are encountered.
Sphagnum Moss is another common media that retains water well and can be used alone or mixed with other media. New Zealand Long Fiber Moss is commonly used for orchids, although Chilean and many other sources of moss are available. Regardless of which variety you use, always look for a good quality moss and avoid those that are stringy and don’t have a lot of bulky fibers. When used alone care must be taken to ensure the moss dries slightly between watering. Sphagnum moss should not be packed too tightly and should never be constantly wet. In our greenhouse orchids grown in fir bark need to be watered three times as often as those grown in moss. (We water orchids grown in bark every week but orchids in moss get watered only once every three weeks)
Orchiata – Growing in popularity, this substrate is produced from 100% pure New Zealand Pinus radiata bark. Orchiata is a hard and stable bark compared to other pine species; however, it needs to be processed from its raw state. This process allows Orchiata to hold water and nutrients on the outside layer of each bark chip, and creates a slightly rough surface for roots to anchor to. Dolomite (calcium magnesium) is applied to Orchiata in the final stages of production and for this reason it needs to be used straight from the bag (do not rinse or wash before using). The dolomite in Orchiata provides the plant with an initial start up supply of these two minerals. Growers must remember though that after a good length of time (around 9 months), dolomite will have broken down and growers must reapply dolomite or other liming compounds to maintain optimum plant growth.
New Zealand Tree Fern Fiber - this is the newest media for orchid growers. It is a fine product full of fluffy pieces and small twigs usually under 2 inches. It holds and wicks water throughout the pot and so is a great media to use for growing moisture loving orchids, and for growing any orchid on windowsills in the home where it is harder to maintain higher humidity. This type of Tree Fern is sustainably harvested.
Peat Moss holds more moisture than sphagnum moss, but the horticultural peat moss commonly found is too fine to be used in anything but a terrestrial soil-like media. However, the harvesting of any type of peat moss is unsustainable and therefore Kelley's has chosen to not support that industry - we no longer sell any type of peat moss product.
Charcoal doesn’t decay but it’s rarely used alone because it doesn’t hold a lot of water compared to other types of media. It’s a great addition when used with bark mixes however because it’s a long lasting ingredient that doesn’t break down. We like to use it because it stays intact and helps to aerate roots even as a fir bark ages and softens. Some growers believe that charcoal also helps to purify the organic material as the orchid media begins to age and decay.
Sponge Rock is rarely used alone (it can float!) but is a great additive to any orchid potting media. Like charcoal, it doesn’t break down which helps to keep mixes from becoming too compact for healthy root growth. Dry sponge rock is very light but it soaks up water and holds a lot of moisture which is why it’s one of our favorite ingredients for a good quality orchid media.
In the past, Tree Fern products sold in sheets or shaped like pots were common in the orchid industry - however the source for these products has been determined to be unsustainably harvested and are no longer available from responsible sources.
Coir is ground up coconut fiber often used in terrariums and vivariums. It is available as a compressed brick that will soften and expand when soaked in a bucket of water.
Diatomite is a porous rock that retains water and nutrients, while draining fast and freely, allowing high oxygen circulation within the growing medium. Diatomite is becoming increasingly difficult to find however, and other moisture holding alternatives may be needed in the future.
Everyone seems to have their personal favorites when it comes to potting so we offer you a large variety of choices. Being orchid growers ourselves, we have access to any of the orchid media mentioned and after many years of use have developed custom orchid mixes for all types of orchids. We personally use and highly recommend any of our custom "KK” Potting Media for the best in orchid growing.