Oeoniella polystachys is one of the few Angraecoids that inhabit all three island chains that surround Madagascar; the Comoro Islands west of the northern tip of Madagascar, the Mascarene Islands to the east of Madagascar and the Seychelle Islands to the north and northeast of Madagascar as well as inhabiting the lowlands of eastern Madagascar itself. An epiphyte that grows primarily on trees not much higher than sea level.
The main reason I started growing Oenla. polystachys is because of the sub-tropical growing conditions here in South Florida. It thrives on large amounts of moisture and has a very short rest period. I started with plants in pots and mounted to tree-fern totems. In just a few short months, I eventually mounted all of the plants due to the aerial roots coming from the plant as it grows. It is almost always in a growing phase, no matter the time of year. As you can see in the image below; it was potted as a seedling and already in bloom for the first time. After learning more of the plants characteristics and realizing that it climbs somewhat, I thought it best to mount.
Oenla. polystachys first time blooming
Mounted to a tree-fern totem, Oeoniella polystachys will eventually start attaching itself to the totem. Aerial roots will form up the length of the plant usually to within 4 inches (10cm) from the top. It is best to have a bed of moss at the base to help hold moisture until the aerial roots have taken hold. The roots form just above the old inflorescence or opposite the leaf axils. Most of those roots will find the totem material and grab hold. Although I eventually mounted the plants that I had put in pots, doesn't mean you shouldn't grow them that way. My suggestion is that the pots be at least 5 - 6 inches (13-15cm) wide and a medium that would allow fast drainage and giving the roots the air that they need. The stems of the plants have the capability to grow to 24 inches (60cm) tall but are very seldom seen that high. To keep the plant from dropping over or becoming pendant, they should be staked or supported in a manner to keep them erect. Oenla. polystachys can start to branch heavily and keeping it erect will give the added support necessary.
Plants that are mounted should be watered daily and when temps reach above the mid 80s F, they should be watered or misted a second time about two - three hours prior to sunset. Allowing the plant ample time to dry before dark. Plants that are potted should be watered every 2 - 3 days and when warmer temperatures arrive, mist the plant mid to late afternoon. As stated earlier, Oenla. polystachys has a very short rest period. Watering should not be backed off unless temperatures drop below 70 degrees F.
Oeoniella polystachys will do very well in a warm greenhouse in the cooler/colder parts of the northern hemisphere while mounted or potted. If the plants are kept indoors such as a home, they should not be exposed to temperatures below 70 degrees F for any great length of time. As long as warm temperatures are maintained, watering habits should not change. Please note; if temperatures do lower, watering can be cut back to every other day when mounted and every 4 days while in a pot.
Oeoniella polystachys mounted to a tree fern totem
Oenla. polystachys is capable of taking very bright light as long as it is diffused or spackled the entire day. Most of my plants receive a fare amount of direct sunlight until about noon or mid-day. During the hotter part of the day, mid-after to late afternoon, the light is toned down. A bright shade or 25 percent spackled light works well. It is imperative that a good air movement be available; if it is not, do not expose the plant to any direct sunlight, keep it in a bright shade or a spackled light.
A mature, well nurtured plant should bloom or be in bloom twice a year; with a 2 - 4 month break in between. The inflorescence develop at the opposite side of the leaf axils and are about 6 - 10 inches (15-25cm) long. Each inflorescence carrying 10 - 15 flowers. Mature plants can produce 5 - 7 spikes at one time. The flowers range in width, 3/4 - 1.5 inches (2-4cm) across. The spur/nectary is about 1/4 inch (.6cm) long forming at the base of the lip and tapers at the tip. Flowers can last 3 - 4 weeks and longer if the plant is protected from harsh weather conditions and are fragrant in the early part of the evening.
My plants are fertilized every 7 days with a well rounded and balanced fertilizer year round. They are treated every 30 days with a systemic fungicide that I switch every three months. I am always on the lookout for signs of fungus on the bottom side of the leaves. A wet climate for too long of a period or cooler weather can bring about fungus issues. Keeping a quart spray bottle of a topical fungicide is a great idea.
Oeoniella polystachys is a phenomenal plant for those that keep warm conditions year round. Like any other Angraecoid, give it what it requires and then be prepared for outstanding flowers.