How We Grow Cattleyas
Most everyone is familiar with the voluptuous, fragrant “corsage” orchids commonly known as cattleyas. This common name encompasses a large number of closely-related orchid species in many genera (singular: genus) and their hybrids. They are native to the American tropics and subtropics, and are among the most recognizable orchid flowers anywhere in the world.
The species readily interbreed, and because it’s possible to make fertile hybrids between and among several genera we have an enormous number of complex intergeneric crosses as well. The orchid plants we call “cattleyas” may be species or hybrids within the genus Cattleya, or they may be close relatives (Laelia, Brassavola, Sophronitis, Epidendrum, Encyclia, Broughtonia), or hybrids among these genera. Although botanists have a fancy name for this group of orchids, they are also known as members of the “cattleya tribe”.
Fortunately most of the species and hybrids of the cattleya tribe are easy to grow, and some are highly recommended for beginners’ collections. Many of them adapt beautifully to our subtropical conditions, doing equally well in pots and other containers, or naturalized in our trees. Their extravagant, often highly fragrant flowers are popular with growers everywhere.
Cattleyas are sympodial orchids (unlike Vandas, which are monopodial). They have a thick horizontal stem (the rhizome). New growth sprouts from buds on the rhizome, and a healthy plant may grow from multiple points on the rhizome. Each new growth, or “lead”, begins with a bud near the base of the previous growth. Plants tend to grow horizontally rather than vertically and most cattleyas will grow out of their pots within a few years.
In their native habitats, the cattleyas (and most of the closely related species) are epiphytes. They grow on the limbs and trunks of trees, but are not parasites. The roots of epiphytic plants (including orchids, as well as some bromeliads, ferns and aroids) are specially adapted for this environment. The plants take no nourishment from the tree itself; their roots absorb moisture and nutrients from the debris that collects around the roots. Cattleyas are also adapted to seasonal changes in rainfall amounts. The thickened stems, called pseudobulbs, store moisture for the plant to use during the dry season.
Potting media –These orchids are highly adaptable and will grow well in pots, baskets or on mounts (cork bark, driftwood, tree fern). They are not generally fussy about the growing medium as long as it is very open, well-aerated and free-draining. Remember, they are adapted to growing in the trees, where they are subject to heavy rains alternating with breezy, dry conditions. The plants need good air circulation around the roots. This is perhaps the most critical element in caring for cattleyas, as the plants will not do well if their roots are smothered with soggy or poorly-aerated potting material. Different potting materials have different characteristics, particularly with respect to moisture retention. No one material is better than another – each has its advantages and disadvantages. Choose a medium that will be appropriate for your conditions. If you water your plants frequently, use mounts or clay pots with an extremely free-draining medium such as Aliflor or Hydroton (expanded clay pellets) mixed with a little chopped tree fern and redwood chips. If you water infrequently, choose materials that will hold moisture somewhat longer: plastic pots, or a mix that includes perlite.
Here at R.F. Orchids, we grow cattleyas in pots, in baskets, and mounted. Our preferred potting mix is Aliflor or Hydroton with treefern and redwood, in clay pots; this works well for us under our greenhouse conditions. If you’re using a different mix and your plants are doing well, stick with your regimen. Remember, the plants are adaptable; there is no single “best” potting medium. Many cattleya orchids grow well in slat baskets or mounted. This assures good air circulation at the roots – as long as the basket or mount isn’t rotten! – and is the closest thing to their natural habitats. You can add some coarse expanded clay pellets or hardwood charcoal to the basket. Once established, mounted cattleyas can remain undisturbed for many years. Potted cattleyas may require repotting every 2-3 years, depending on their growth rate.
Water – Watering cattleyas is dependent on several factors. The potting medium should be allowed to dry somewhat between waterings. If your plants are potted in a moisture-retaining mix, this may mean watering twice a week. For a more open, porous mix, you may need to water every two or three days. Cattleyas mounted on cork or driftwood can be watered every day while they’re growing, if the air circulation is good and the mount dries during the day. Always water early in the morning if you can. During the cooler, shorter days of winter, water less often, particularly if plants are not actively growing.
Light – Like most flowering plants, cattleyas want bright light in order to grow and flower well. They will take fairly high light levels early and late in the day, but should be protected from direct midday sunlight. You can easily tell if a cattleya is getting the right amount of light by looking at the foliage. If the plant’s leaves are rich, dark green, it isn’t getting enough light; if the plant is light yellow-green, it’s getting too much light. The correct light levels produce foliage with an attractive medium green color. If your cattleyas don’t flower, lack of light may be the culprit, but don’t move plants abruptly from too-shady to very bright conditions. Move the plant gradually to brighter conditions or you may scorch the foliage. Some species in the cattleya alliance grow in nearly full sun in their native habitats, although most of the commonly cultivated species and hybrids prefer just slightly shadier conditions than this. Let the foliage color be your guide to the amount of light necessary for good growth and flowering. As a general guide, cattleyas want very bright shade, with some sunlight early or late in the day.
Fertilizing – In “captivity”, cattleyas do best with supplemental fertilizing. The best fertilizer depends on the potting medium you use. For mostly inert potting materials (expanded clay is completely inert, as are charcoal, lava rock, perlite and similar manufactured materials), we recommend a balanced fertilizer with micronutrients. Peter’s 20-20-20 is one option, and it’s the fertilizer we use. Jack’s Classic 20-20-20 is packaged for retail consumer use. For potting materials that are largely comprised of tree bark, a fertilizer with a higher nitrogen content may be appropriate; high-N formulas have a higher first number, such as 30-10-10. The normal decay process of bark uses nitrogen, so you may have to supplement it. If your plants are getting plenty of light but they’re still dark green and not flowering very well, the problem may be too much nitrogen.
Growth Cycles – Most species cattleyas (and their species relatives in other genera) have relatively distinct growing and resting phases during the annual cycle. While the plants are actively growing, they should be fed and watered regularly. We fertilize weekly during the growing season, and cut back on both fertilizer and water during the shorter, cooler days in winter. Hybrids in this group, however, may or may not show a distinct growing/resting pattern. Some do stop growing and rest in the winter, some do not. Learn to recognize the signs of growth and the signs of resting, and care for your plants according to their needs during these parts of the cycle. If they are actively growing (no matter what time of the year it is), make sure they get regular water and fertilizer. If they are not growing, cut back on both fertilizer and water until you see signs of growth again. The resting phase may last a few weeks or a few months.
Temperature – Most cattleyas are native to mountainous areas of tropical America, and they prefer intermediate temperatures. A few come from warmer or cooler regions, but in general cattleyas do best with daytime highs in the 80s, and cooler nights. In winter, they will withstand overnight lows in the 50-55F range easily, and with protection from the wind a brief drop into the mid-40s is generally not a problem. During cool periods, keep the plants somewhat drier than normal. (Note: Cattleya violacea from Brazil is very cold-sensitive, and some of the species in related genera are also warm-growing. If in doubt, protect the plants from temperatures below 50F.)
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