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Hints on Potting and Potting Media

Leo Holguin - originally published February, 1968

The question we hear most often is "When is the best time to repot?" Some people prefer to pot only in the spring, assuming that this is the growing season and therefore the best time to repot. In some cases this is true. When potting cattleyas or allied genera, one must remember that some species have a definite resting period and it is probably better, in most cases, to wait and pot when the growing season starts. However, the majority of cattleyas today are complex hybrids with little or no resting period.

Figure 1: A plant growing over the edge of its pot; obviously in need of repotting.

Repotting is usually done when plants are through blooming and are crowding the inside of the pot, or growing over the edge. The best time is when there are signs of renewed root action, such as roots commencing to grow from the base of the new growth. Whenever possible, it is best to wait for the new growth to make up and pot just before the new roots start to show at the base of the rhizome. However, if the medium is broken down, or sour, it is best to move the plant into fresh material as long as it is not in bud. If the plant is in bud and in poor condition, it is best to remove buds before repotting.

In some cases, root action will begin before the growth is made up. It is best to pot at this time to save the roots. In any event, potting should not be done just prior to blooming. This will prevent the flowers from developing properly. Allow sufficient space in the pot for two years' growth. Be sure and tamp the material in good and firm. In this manner it will retain moisture for a longer period of time and less watering will be necessary. If the material is too loose, you will have to water more often and you may have to repot before two years.

If one has a very good variety of cattleya and wants to keep it growing with as little setback as possible, I would suggest adding what I call an "annex." Some people call it a "nose bag" or "piggyback". This is especially good if the plant is over the edge of the pot, starting to root and in bud about ready to flower. By use of an annex, you can save roots and flowers, and the plant will grow on with more vigor. Later, when the plant is well rooted in the annex, you can remove it without disturbing the medium and pot on if you wish, or leave it for another season.

Figure 2: An "annex" attached to the pot,
allowing the new growth to
establish itself therein.

Assuming the plant is in a 6†(15-cm) pot, the idea is to get a 6†(15-cm) pot and try to break it in half (not easy). The best way is to find one that is already cracked on one side. Hold the opposite end along the rim, then hit downward with a potting stick near the crack - and a V-shaped area should be left. Trim this V-shaped area with a pair of pliers to fit against the original pot. Next, take a piece of flexible wire about 24" long, bend together at the center and twist the two wires together about two inches, then bend like a hook, and hook over the rim in back of the pot. Bring under the rim of the pot around the annex and twist the wires together again, then pull up to the rim of the annex and loop over. To tighten, take a piece of wire about three inches long, make a hook at one end, and insert this hook in the rim of the original pot at a point where the two join together. Then loop around the wire and pull up tight. Do the same on the other side. With a little patience, it will work. If you want to miss all this fun, take a plastic pot, use clippers and cut it to fit.

In regard to potting media, I think that just about every material with any possibilities at all has been tried. Fir bark and redwood bark mixes are very popular (Editor’s note: Fir bark and mixes of fir bark are less popular in hot, humid climates because they break down too rapidly – especially when plants are grown outside without protection from natural rainfall) because of the ease in potting with these materials. A mixture of one part redwood bark to three parts of fir bark seems to work very well. This mixture, assuming you use a good grade, and depending on how well it is packed around the roots, has lasted three years (Editor’s note: Today’s fir bark is of much poorer quality than when this article was first published. As a result, fir bark available today last typically about 18 months to two years at the most). Add ten pounds of dolomite lime to a cubic yard of material, or approximately one pound to a 2.5 cubic bag. Moisten the material before using and you will find that it packs better.

Some growers use straight fir bark as well as straight redwood bark with no additives, and with good results. At one time these materials were inexpensive, but like everything else, the price has gone up. As quality decreases and price increases, other materials will continue to be tried. For adult cattleyas, use medium grade; for seedlings, use the fine grade. For best results when using this material, regular feeding is a must.

Another mixture that has come into use in the past several years consists basically of 3 parts fir bark, 1 part German peat moss (This is a very different product from domestic or Canadian peat moss commonly available in garden centers. As it has become more and more difficult to find, other moisture holding products like chopped sphagnum moss and coconut husk chips have been used as replacements), 1 part sponge rock, and 1 part redwood bark and dolomite lime. I do not know the amount of dolomite lime used, but would assume ten pounds per cubic yard is about right. There are some modifications to this mix. Some growers add other ingredients, some less, depending on their area and success in growing in this type of mix. As with straight fir bark, regular fertilizing is recommended.

I hope the above suggestions will be of some help. However, most growers have their own preferences as to potting mixtures, and you will have to learn by experimentation to see which will do the best job of growing for you in your particular area. 2005 Armacost Ave., West Los Angeles, Calif. 90025.