AOS Culture Sheet
Paphiopedilums, the lady's-slipper orchids, originate in the jungles of the Far East including Indonesia. They are semiterrestrial, growing in humus and other material on the forest floor, on cliffs in pockets of humus and occasionally in trees. They are easy to grow in the home, under lights or in the greenhouse.
Light is easier to provide for paphiopedilums than many other types of orchids. They require shady conditions, as in the home in an east or west window, or near a shaded south window. In the greenhouse, shade must be provided. Give about 1,000 to 1,500 foot-candles. In the home, fluorescent lighting is excellent; suspend two or four tubes 6 to 12 inches above the leaves.
Temperatures for paphiopedilums cover a considerable range. Paphiopedilums are traditionally separated into two groups: the warm-growing mottled-leaved types and the cool-growing green-leaved types. A third, increasingly popular group is the warmer-growing strap-leaved multifloral paphiopedilums. Warm-growing types should be kept at 60 to 65 F during the night, and 75 to 85 F or more during the day. Cool-growing types should be kept at 50 to 60 F during the night and 75 to 80 F during the day. However, many growers raise all plants in the same temperature range with excellent results. The plants can stand night temperatures in the 40s if necessary (as when grown outside in mild climates), as well as temperatures to 95 F. Care must be taken to protect the plants from rot when cold (keep humidity low, and avoid moisture on leaves or in the crowns of the plants), and also to protect from burning when hot (shade more heavily and increase humidity and air movement around the plants).
Water must be available at the roots constantly, because all plants in this genus have no pseudobulbs. All of these plants need a moist medium - never soggy, but never dry. Water once or twice a week.
Humidity for paphiopedilums should be moderate, between 40 and 50 percent, which can be maintained in the home by setting the plants on trays of gravel, partially filled with water, so that the plants never sit in water. In a greenhouse, average humidity is sufficient. Using an evaporative cooling system in warm climates can increase the humidity. Air movement is essential, especially when humidity is high.
Fertilize on a regular schedule, but care must be taken to avoid burning of the fleshy, hairy roots. High-nitrogen fertilizers (such as 30-10-10) are recommended when potted in any fir-bark mix. In warm weather, some growers use half-strength applications every two weeks; others use one-quarter strength at every watering. It's important to flush with clear water monthly to leach excess fertilizer, which can burn roots. In cool weather, fertilizer applications once a month are sufficient.
Potting should be done about every two years, or as the medium decomposes. Seedlings and smaller plants are often repotted annually. Mixes vary tremendously; most are fine- or medium-grade fir bark, with varying additives, such as perlite (sponge rock), coarse sand and sphagnum moss. Moisture retention with excellent drainage is needed. Large plants can be divided by pulling or cutting the fans of the leaves apart, into clumps of three to five growths. Smaller divisions will grow, but may not flower. Spread the roots over a small amount of medium in the bottom of the pot and fill with medium, so that the junction of roots and stem is buried 1D 2 inch deep in the center of the pot. Do not overpot; an average plant should have a 4- to 6-inch pot.
The Canadian Orchid Congress
PAPHIOPEDILUM: Lady Slipper Orchid
These Asian relatives of our native lady slippers come in an almost infinite variety of shapes, sizes and colors, and include those that are very easy to grow and bloom and others that are much more difficult. Fans of green, or mottled leaves give rise to flower stems carrying one or more flowers in colors of white, green, yellow, earth tones, pink, red and black.
Healthy Paphiopedilum start with healthy roots:
Pot in a fine medium. Fir bark mixtures are best, with 0.5 to 1.0 cm chunks of bark, perlite and charcoal.
Repot when medium starts to decompose or new growths have reached the edge of the pot. Check for decomposition yearly, on newly purchased plants or if leaves are limp.
Remove old medium if it is loose and any rotting roots (dark and soft to touch); choose a plastic pot that will only just hold the roots of the plant and center plant in new pot.
Paphiopedilum require a basic (rather than acidic) mix. This is achieved with extra calcium. If your water does not have a high calcium content, top dress the medium with dolomite lime or crushed oyster shell and replace when it has disappeared.
Roots should be slightly moist at all times. Water when medium has begun to dry but while it is still damp. Water thoroughly, with a volume of water at least equal to that of the pot.
Do not use water softened in salt-consuming water softeners. Despite the need for extra calcium, low mineral water is preferred, such as naturally soft water or rain water. If hard water is used, water very heavily to flush minerals.
Fertilize weakly and frequently with a balanced fertilizer. One-eighth to one-quarter strength recommended by manufacturer for house plants every week in spring and summer and every two weeks in autumn and winter.
Healthy leaves produce more and bigger flowers:
Medium light levels are appropriate. Leaves should be a medium green, usually not yellowish (too much light) or dark
green (too little light). They should be firm, not long and floppy (more light needed).
Two to three hours of sunshine on a windowsill (East or West) or 15-30 cm under a four tube fluorescent fixture.
Leaves should be firm; if soft and desiccated, check roots for rot, and repot if necessary. High humidity (such as enclosing the plant in a plastic bag) will aid recovery if most or all of roots lost, but be careful of rot.
Paphiopedilum do best with 60-70% humidity but when mature will grow and bloom, although more slowly in lower humidity. High humidity is particularly desirable to form new roots, which may not grow properly in low humidity situations. Use humidifier to raise humidity – humidity pans and misting minimally effective. Enclosing plant growing areas is effective but ensure fresh air and air movement to avoid mold and rot.
Grow Paphiopedilum in intermediate temperatures with 14°C minimum winter nights and 29°C summer day maximum. Ensure 6-12°C day/night difference to aid flower formation.
Asian lady slippers usually bloom annually and the flowers last for several weeks:
Maintain plant orientation while spike is growing for best display.
Some types require slightly different conditions
Complex type: Plain green foliage, large round flowers. Medium size plants. Standard conditions.
Maudiae type: Dark green mottled foliage. Easiest to grow, small plant, warmer temperatures and lower light.
Multifloral type: Plain green foliage. Harder to grow, large plant, warmer temperatures and high light.
Brachypetalum: Dark green mottled foliage, bird’s egg flowers. Harder to grow, small plant, warmer temperatures, low light, more coarse medium and much calcium.
Chinese types: Mottled foliage. Small plants, standard conditions, coarser medium. The species delenatii does not require a basic medium.
Commonly known as the lady’s-slipper orchid, Paphs come from the Far East and grow on jungle forest floors or on cliffs. One of the easiest orchids to grow in the home environment as light requirements are similar to those needed for Phalaenopsis or the moth orchid. They are also known for having long-lasting flowers some lasting 2 to 3 months easily.
Paphs do not like to dry out completely and definitely do not want to stay dry for long periods. It is best to water the media thoroughly just as the plant starts to dry out, usually a couple of times a week. Be careful to keep water out of the center of the growths to avoid rot. It is always best to water early in the day so that any water on the plant dries out before it gets dark.
It is said that there are 2 distinct groups of Paphs which determine temperature requirements. The first being the mottled leaf group which is the warmer growing of the two. These warmer growing Paphs generally grow in a 60 to 65 degree temperature at night and 75 to 85 or more during the day.
The second group is the solid green leaf group which tends to favor somewhat cooler temperatures. These Paphs grow at 50 to 60 degrees at night and 75 to 80 during the day.
Multi-florals Paphs have solid green strap leaves but tend to grow on the warmer side.
All that being said, I grow all of my Paphs together with little problems. I keep my night temps in the high 50s and day temps are in the 60s during the winter and 80s during the summer.
Paphs are happy with humidity in the 40 to 50 percent range which can be maintained in the home environment with gravel trays or a humidifier.
Good air movement is always essential where humidity is higher to prevent fungus and rot.
I fertilize using 1/4 to 1/3 strength every time I water rotating between high nitrogen, high bloom and 20-20-20 on a weekly basis. Most importantly with Paphs and Phrags, I do a clean water flush at least once a month to eliminate any fertilizer salts that might have built up during the month. Again, this is very important with these 2 genera as they are most susceptible to fertilizer burn.
Except for the hottest parts of the summer and the dead of winter, Paphs can be repotted at any time and appreciate being repotted. I use a bark, perlite and charcoal mix - larger bark for the larger species and smaller bark for the smaller species generally. It is important to not overpot your Paph as they will grow and bloom more quickly if given just a bit more room to grow when repotting.
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