Since not all accept the name Tolumnia, and all hybrids are labelled oncidium, we will refer to them as equitants. This genera related to the oncidiums, or still in it, is from the Caribbean islands. In their native habitat, they are warm growers, with high humidity for most species. The amount of water depends on which island and which area is their point of origin. T. guianense is from a very arid area of the island of Hispaniola, mainly on the Haitian side where they get most of their moisture from dew. Others are from beachside in the Bahama Islands and are subjected to nearly daily rainfall and nightly dew.

The general conditions for good culture are high light, high temp, high humidity, and water. Since many equitants die from improper watering, to me water is the most important factor in proper culture. The first thing to consider is your media, and that will tell you how often to water. I have seen/used all of the following media: loose charcoal, loose treefern fiber, treefern plaques, cork plaques, and even sphagnum moss ( though I would not recommend it). Each method requires a different watering frequency.

WATER:

This is the first consideration when growing equitants well. Once you figure out how often you are going to water the equitants, then you can choose the potting media. Since equitants don’t have a pseudobulb or other water retaining biological mechanism, they want to have moisture when they need it and want to be dry the rest of the time. We need to supply this need either by having a minimally retentive media or a non-retentive media and adjusting our watering to match the media. OR, do like I do and match the media to my watering schedule.

Equitants want to get their roots wet so they can get the moisture they need, and then they want to dry out so they are not waterlogged. I killed my first cork mounted equitants because I didn’t give them enough water, I watered at the frequency of the ones I have potted. They didn’t appreciate it very much, and expressed it by turning brown.

Potted plants or plants in a water retentive media will need to be watered every two or three days, 2-3 times a week. Plants mounted on cork will need to be watered every day or every other day, but misted more often.

POTTING AND MEDIA:

Potting is the second consideration I use, after choosing how often to water. Match the two methods, and your equitants should do well.

I grow my equitants mainly in clay pots, with loose long tree fern fiber tightly packed into the pot. If a plant has a poor root system during repotting, I will wrap the roots that are present with one or two long sphagnum fibers. Since the water/dry cycle will break down the sphagnum moss and make it less water retentive. So after a couple of weeks, water retention is no longer a problem, at about the same time new roots have formed. Cool timing, the way the two go together. In this method, I water 3 times a week in summer, and twice a week in winter in Miami Florida.

My second most common method is to pot the plant in a pot using medium charcoal chunks. Again, it is a method which will retain moisture for a short time, but then dries quickly. Although some people say that the charcoal will filter out the impurities of the water, I believe that after a few weeks/months, it absorbs (adsorbs) all the stuff it can handle and is then no more effective than any other media. My beliefs only, no other claims are claimed. But it has good qualities otherwise, so who cares. I do like it better than aliflor, although a mix of the two works well. I water 2-3 times a week with this method also. Another popular method is tree fern plaques, hanging with the fibers oriented vertically. This method allows the roots to explore throughout the plaque, and offers water retention with quick drying. I tie a small thin pad of sphagnum moss on the plaque, and then put the plant on the pad. Again, the water retention is not a problem after a few weeks, but allows the plant to have more moisture retention when it is establishing itself. I water these 2-3 times a week also.

Another popular method is to mount the plant on cork. Again, use a small pad of sphagnum moss, and mount the plant to the pad. The best pieces of cork for equitants will have either folds or holes in them, so that the plant's roots will have a place to suck up moisture while the cork is drying. A related method is to use a roughcut cypress board, especially the kind used for outdoor fencing, instead of the cork. Both cork and cypress require daily moisture, a spray or two from a squirt bottle once or twice a day to simulate dew, and a full watering at least once a week or so. I don’t like this method since I don’t want to water every day. A method which does work, but I don’t recommend is sphagnum moss either in a basket or in a pot. You have to watch the watering frequency with this method, and see if the plant is happy and adjust accordingly. If you are experienced this will work, but is not good for those who can't tell if the plant is unhappy from too much water or too little water.

LIGHT:

Light is easy. Give them as much as you can. When I first buy a plant, I don’t know at what level it was previously grown, so I start at low cattleya light and move it brighter over a week or two. They need it bright to bloom. If the leaves start to turn red, cut back slightly on the light, but maintain a high level, at least cattleya light. They can do well indoors on a windowsill, or under metal lights, but I had problems blooming them under flourescents indoors. They grew well, but no blooms although I only had a two light setup, so it wasn’t that bright.

TEMPERATURE:

Since these plants originated in the Caribbean, they like warm temps. They don’t like to go below the 70F range. They like it in the 90's by day, with the 80's by night. They will tolerate temps in the 80's by day, with nights in the 70's, IF you can keep the light bright they will still bloom. So windowsill is no problem with the temps.

PESTS:

The most common pest to attack equitants is scale. You have to be very determined to get rid of scale, since the larva and eggs can get down in between the leaves and are hard to reach. . I separate the plant, and its closest neighbors, so that the infestation doesn’t spread further.

The first line of defense when you first see a scale is to use an alcohol based mix to kill the little blighters and rub them off with a brush. I use a 50/50 mix of water/alcohol with a few drops of soap, and scrub with an old natural bristle 1/2" paintbrush. I have cut off the bristles at about 1/2 inch, so there is not much play while it is not too stiff. I like this better than a toothbrush. After I am done, I set the pot in a bath of the mix, and let the pot soak for 10-15 minutes. Then I repeat at 4-7 day intervals for a couple weeks. If this doesn’t get rid of the scale, I move up to a chemical mix, preferably a systemic insecticide. With a systemic, I don’t need to contact the insecticide by scrubbing with the brush. Repeat at 7 day intervals for a couple of weeks. Use the concentration recommended on the label, a weaker solution just breeds resistant bugs. Also, change insecticides every so often, so that resistant bugs are not breeding.

Another problem with equitants is that weak plants are susceptible to bacterial infections. I use rd20 or phyton27 when it happens. You can tell when they are infected because the fans turn yellow and fall off.

CONCLUSION:

The two main variables are watering frequency and potting media. Light and temp are constant for all the equitants, high levels of each. If you follow the matching method I outlined above, you should have no problem with culture.