In the November 2006 issue of Orchids magazine pages 840-843, I was fortunate enough to read the article by Charles Rhodes entitled “No Longer A Killer.” This launched the beginning of a very pleasurable hobby. Prior to this growing strategy I was a bona fide KILLER. Sometimes they lasted a while but generally not for long and I was very discouraged. Below I would like to outline some of what I have learned from this magazine article, and from other on-line references. From that base and my own experimentation and observation I have evolved a system that is satisfying and low maintenance. These techniques (very painfully learned) have brought me to a point of near 100% confidence that I can purchase a new and lovely “treasure” and have it not only survive but thrive! Even those with poor roots usually do well. Every commercial grower and successful hobbyist has worked out their own system but the variables of one’s own schedule for work, travel, etc. plus your growing space and location result in variations in sunlight, watering, fertilizing, etc. The commercial growers regulate this very closely but some times we can not. So let’s make it simple:
1) NON ORGANIC MEDIA: All types of bark, sphagnum, etc. eventually decompose and rot, thus here cometh the root eating bacteria. Orchids need a substrate for moisture and air and someplace to cling to. Various types or rock and manufactured media are available and each has its own attributes. Here are my favorites:
A) Light Weight Expanded Aggregates (LECA) – a light weight expanded silica-clay pellet that not only retains moisture but has the capacity for capillarity or “wicking”, i.e. the ability to draw moisture up and through-out the media. The round nature of these pellets provides good air flow within the media. Two popular brandsof this type of material are Hydroton and Primagra. Other types and brands of “rock” are also used but an important characterist needs to be that of capillarity. Most of my experience is with the hydroton because it is locally available.
B) Diatomaceous Rock: There are several brands of this type of natural rock that is modified by heat and other techniques and contains a high amount of silica. From what I have observed it holds moisture very well, has reasonably good interspace for aeration but does not have the ability for wicking/moisture transfer up into the media found in the LECA material. All of these medias should be rinsed and soaked in water overnight and kept soaked until placed into the container.
Using these types of media, the size of the pots is less critical. Common “wisdom” claims that the roots grow best out near the sides of the pot to reach better oxygenation—with the rock or pebbles the entire pot is well aerated.
2) CONTAINERS: Various websites market a variety of plastic pots that are durable and have a manufactured set of two small holes up on the SIDE of the pot (with no holes in the bottom). Any non-vented plastic pot can be modified by burning holes ( approx. 1 1/8” up from bottom) with a soldering iron. This is the essence of the semi-hydroponic technique. The media at the bottom of the pot is fluid saturated and that above
receives moisture by the capillary action described above, wetter at the bottom to drier above. Now we have rather constant moisture and air through-out the pot. VIP! The media needs to be stacked about ¾ inch above the level of the holes(and fluid) prior to adding the plant so the roots never sit in the water! This technique works great for almost any orchid I have dealt with so far. A special point should also be made that when watering/fertilizing, do so from the side of the pot so that the main root base of plant does not become too wet. Also, as commonly known, keep the crowns of the phals and phrags absolutely dry! And very importantly, occasionally “flush” the pots thoroughly with the water hose ( I do this every 2 weeks) to remove retained salts, etc.
3) FERTILIZER: The two I have used are DynaGrow’s “liquid grow” 7-9-5 and MSU (Michigan State) liquid but various others are available. There are some differences but both seem to work well. Add 5 ml ( 1 teaspoon) per gallon to the watering solution and keep the reservoir in the pots wetand do not let them dry out. Other additives such as pH modifiers and cell stabilizers may be used as well. In the open bottom/saucer technique described below, I use conventional fertilizing, e.g. nutricote (dynamite) 180 day into the pots plus weekly spraying of dilute general purpose fertililizer. With the initial re-potting I soak the rock media in the liquid fertilizer plus add a root stimulator. Do not use this high concentration solution thereafter as it will damage the roots! For those plants that start out with poor roots a very dilute solution of the stimulator may be added until the roots flourish.
Now we have what I would like to call the “MIGHTY TRIAD” of constant moisture, constant air and constant nutrition. This eliminates the most troublesome variables!
SUNLIGHT: You know what to do here.
AIR FLOW: Always a good thing.
CONTAINER VARIATIONS: This gets creative. When I started growing outside of my screened porch, a problem was encountered. Detritus from leaves, pollen, etc. would fall into the pots collecting in the bottom reservoir and create rot. This mandates more frequent flushing and “tipping” of the pots to drain all of the water out of the bottom. Coconut fiber can be placed in the top of the pots to act as a filter to prevent the leaves from falling down into the media; this is effective but labor intensive. These classic semi-hydro pots are in fact a semi-closed system with poor drainage and this is a weak link for outdoor growing. The plants, however thrive outdoors. Now for the variations. We all know that different species have varying water needs. The various LECA and rock media retain and wick water differently and some fine tuning for your type of orchid is needed. Thus if we place a standard orchid pot with holes in the bottom onto a saucer, this creates a reservoir of water, i.e. Semi-Hydoponic. The type of pot can vary as classically known: slits up the side and/or clay allow more air and dry out easier ( for cattleyas and other “dry side” orchids). Plants requiring intermediate “wetness (dendrobiums, oncidiums) would probably go into a clay pot with no side vents plus the saucer and those requiring high moisture (phaleonopsis, prhragmipediums, etc.) would go into a plastic pot plus the saucer. The relatively cheap plastic pot/saucer combos from the home supply stores may also be used for any and all by simply adding some side holes into the pots with a small soldering iron, more holes—more air. These pots are easy to hang using vanda wire hangers and small holes in the rim of pot. With a little ingenuity the saucer may also be attached to the hanging pot thus yielding considerable flexibility as to where your orchid is placed. The saucer technique may be tuned a bit for the outside plants—if there is rain several days in a row, simply remove the saucer temporarily and the rain will not overwhelm the potting media. Remember that all of this rock-type media will dry out much faster than bark and watering habits need to be adjusted accordingly. I also pot many of my cattleyas in tight meshed baskets with the pebbles only but are watered daily—this works great.
For all new plants that I purchase with marginal root structure, these are placed first into the true Semi-Hydro pot, this would include keikis and rootings. After the roots become large and healthy, I transfer them to one of the above open saucer or open air techniques for simplicity and low maintenance. One “heretical” thing I have done routinely for several years, and have yet to regret, is to repot any new orchid, even if fully blooming!! I have not lost any blooms and believe this is a better long term strategy to protect and nurture the plant. If the plant is already potted in a rock media, I might leave this alone until repotting would normally be required. An observation about repotting after transitioning from the semi-hydro pots is the amazing root structure present with rarely any root rot at all! Obviously this makes any re-pot a much simpler task—simply pull the plant out and place it into a larger pot and add more media!
That’s it for now but the above is still a work in progress. However, these techniques noted above have made my orchid “addiction” much less painful!
Have fun!
BiminiBob
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