ORCHIDOPHILOS by Tom Sheehan
Frequently I am asked by an orchidist how to tell whether or not he/she is doing a good job of growing his/her plants. Actually, this is a good question, because often times we look at our plants and wonder how well they are thriving, but have nothing for comparison. It is relatively easy to tell whether your plants are up to par or not. Color is always a good positive factor because the intensity of green will vary among genera, with some well grown plants dark green and some almost yellow green. But there is an excellent indicator that everyone can use to evaluate plants.
With sympodial orchids, e.g., Cattleya, Dendrobium, the new growth in mature plants should be equal to or larger than the height of the last growth, while in unflowered seedlings it should always be larger. If the newest growth is smaller, then you are not doing a good job of growing, or the plant may be suffering from soluble salt damage or possibly some pest problem and it is time to do something.
In monopodial orchids e.g., Vanda, Phalaenopsis, the situation is very similar. With these plants the spread of the new leaves should be equal to or greater than the last mature leaf or set of leaves. Again, in seedlings you expect each new leaf to be larger until the plant is mature and flowering, at which time the new leaves should be of equal size from then on. A well grown large strap leaf Vanda plant should have all the leaves the same length so the leaf tips would all touch a stick held perpendicularly to the leaves. I should point out that you are comparing mature leaves, not developing leaves. Consequently, you must be able to recognize the difference for all the genera you are growing. Once you do this the rest is easy.
Another problem that occurs in the fall of the year is the formation of brown papery sheaths on some Cattleya plants. Novices often cut them off, thinking they have lost the flowers, and this is not so. Those species and their hybrids that have the “mossiae” growth cycle, e.g., trianaei, labiata, produce their flowers from within the papery bracts. These plants flower from early fall through May, The other group, known as “gigas” flower in spring and summer while the sheaths are green and succulent. So be careful before you cut off any papery sheaths this fall when checking your plants. Gently squeeze the sheath and you will feel the buds inside.