As you can surmise from these entries, many Cypripediums have yet to be artificially produced in large numbers, especially by means of micropropagation techniques. Of the 59 species, recognized varieties, and naturally occurring hybrids listed here, only 14 of these have been propagated in any quantity over the last two decades.
Moreover, 11 of these are either from the subsection Cypripedium or are hybrids of that subsection, and out of those, three are varieties of one species, C. parviflorum. Clearly, this group is the easiest to cultivate with known propagation techniques. Indeed, only 3 species outside this subsection have been mass propagated to adult size, C. californicum, C. guttatum, and C. reginae. In truth, of these only C. reginae has been truly mass produced to date. Regardless, lady slipper orchids remain some of the most sought after of all terrestrial orchids to this day – hence, there is a big disconnect between demand for them and the supply.
So, this begs the following questions, why is this the current situation and where are plants in cultivation coming from? The second question is easy to answer – many if not most are coming from the wild. The first question is more difficult. The bottom line is that most species are either tricky to germinate and/or they do not grow well afterwards. Others are simply slow growing, taking many years to bloom. Still others have high mortality rates from seed to adult size.
The simple truth is that before 1990 only a handful of expert growers such as Carson Whitlow and Werner Frosch were even attempting Cypripedium micropropagation. In the mid 90s that began to change with quite a few growers world wide getting in on the game. Dr. Bill Steele helped wax the wheel by making his nutrient formulations free and public to all. By late in the decade many thousands of Cyps, both naturally occurring and artificial hybrids, had been produced and sold. Recently, the focus of many propagators has been on artificial hybrids since they offer more variety and most are much easier to grow than the species. The upshot is, there is still a lot of work to do in effectively growing most of the known Cypripedium species.
For these reasons and others, Cyps remain a niche market in the horticultural trade. This situation also brings the inevitable – high prices for even the easiest and most commonly produced plants. All of this goes beyond the scope of this article though, so perhaps this discussion should handled at another time.
Here are the remaining plants. The names highlighted in blue are clickable links to more comprehensive pages about that plant:
japonicum – a widely kept species that remains difficult to grow and apparently very difficult to flower even after being firmly established. It is found throughout much of central China, the Korean Peninsula, and virtually all of Japan. As such it is fairly indifferent to temperatures enduring both severe and mild winters, and cool to very warm summers. It needs a lot of room to range since the distance between growths can be 15 centimeters or more. It is completely intolerant of dry conditions and is also a heavy feeder. Best grown in the ground in acidic conditions in a decidedly organic compost. Production from seed has been very difficult, so plants in the trade are virtually all wild sourced. When happy it forms formidable colonies with thousands of flowering stems. Not an easy species. USDA zones 4-9.
kentuckiense – widely grown and easily available. Virtually all plants in the trade are lab propagated since it is very easy from seed. Any free draining compost should work. Many growers suggest using a lot of sand in the mix. Neutral and slightly acid conditions is best. Straight forward in cultivation even in hotter climates with cold to cool winters. USDA zones 4-9.
lentiginosum – occasional smuggled plants show up on the world market, most end up in Europe, and no doubt to die. Like other members of Trigonopedia, this one is difficult to grow and little is known about its cultivation. Likely it demands a compost low in organics and fairly dry winters. Being a native of southern China and northern Vietnam, it probably isn’t very cold hardy either. USDA zones 7-8.
lichiangense – another difficult species that has been exported in quantity throughout the world, but in recent times has become less available. The main reason is that virtually all the plants exported ended up dead within a very short time. Successful long term cultivation is apparently difficult, but not impossible. Little, if any, organic matter should be used in the compost and the leaves have to be kept off the surface of the grown medium. This can be accomplished by placing cotton or the like under the leaves and only watering the plants from below (via capillary action, etc.). Attempts at growing them in the ground long term will most likely end up failures. Currently seedlings are being grown by a number of people and in time this species could become more common in the trade. It will always remain a very difficult plant to grow. No adult size lab propagated plants yet exist in the trade to my knowledge. USDA zones 6-7.
ludlowii – a mysterious rarity that lives in a very confined area of SE China on the border of Tibet. Not in the trade so far, in fact it remains almost a “ghost”. Virtually nothing is known about its cultivation, or for that matter, its existence beyond herbarium specimens!
macranthos – widely cultivated and widely available, but mature specimens remain difficult to obtain, especially in North America. Many plants have been sourced from the Chinese/Russian border and while some have been lab propagated, many more are wild collected. Fairly easy in cultivation, but not simple. Again, a mostly inorganic substrate should be used that is perfectly draining. Unlike its western Chinese cousins, this one is much more forgiving about winter rains and warm spells. More choice varieties, especially v. rebunense and v. hoteiastumorianum from Japan, are rare in cultivation and remain very expensive. One of the most choice species in my opinion. Reportly very slow from seed to flowering. USDA zones 3-6.
x macrosaccos – The natural hybrid of C. calceolus and C. shanxiense. Specimens started showing up in the West from collected material along the Chinese/Russian border some time ago. Cultivate as per C. calceolus. Probably easier to grow than either of its parents, both of which are a bit touchy. USDA zones 4-6.
margaritaceum – another plant that was exported throughout the ’90s to Europe and North America. Most perished and today even seedlings or divisions are nearly unavailable. Perhaps a few wild plants remain in cultivation here and there, but no one is talking about them in the open. Cultivation as per C. lichiangense. Very difficult in cultivation. USDA zones 6-7.
micranthum – widely, but rarely cultivated miniature species and to date, all wild sourced. It is reportedly not so difficult once established, but a bit touchy. Wild collected plants offered are either established ones or recently dug. Grow as you would C. bardolphianum. Not lovely, but certainly a neat little colony forming species. USDA zones 5-6.
molle – Like C. irapeanum, this one is nearly impossible to grow. It also is a very rare plant, found only in the Mexican state of Oaxaca. USDA zones 10 and higher.
montanum – widely grown and widely available, but remains difficult to keep outside its native range. Wild collected plants in particular are nearly impossible to reestablish, with most dying in a season or two. It requires evenly moist soils, but as the summer wears on it doesn’t like to have wet feet. In humid, hot summer areas this species will not long survive. Even seed propagated plants have proved to be really tough to keep going. Not commonly offered, but consistently offered here and there. Very difficult to establish and maintain in most climates – dry and cold areas are the best candidates. USDA zones 3-6.
palangshanense – wild collected material has been exported to the world market through the ’90s up to recent times. Perhaps some plants are being maintained in Europe and maybe even a few in the states. Not much being said about them however. A few seedling plants are offered in Europe each year. Like C. debile, it probably is difficult to maintain in the long term, but not impossible. In cultivation it probably should be handled like C. debile however grown at a near neutral pH. Being a western China plant, it would be wise to protect it from winter rains. USDA zones 5-6.
parviflorum v. pubescens – a widely grown and very available plant. Many thousands of plants are grown and sold each year throughout the world. Any free draining woodland soil will do. They seem to prefer near neutral conditions, but can easily handle fairly acidic soils. Easy species and a great one to start with. USDA zones 3-7.
parviflorum v. parviflorum – almost as easy as its big brother. A tad bit more difficult to get, but still very available. Southern races of this variety are found on rather dry, acidic soils, and have been more difficult to maintain than the northern forms. USDA zones 3-7, possibly even 8.
parviflorum v. makasin – this disputed form is very distinct looking and has been widely cultivated for many years. Both wild sourced and lab produced plants are available on the world market. Easy in a well drained, gritty compost with a fair amount of organics. Forms large clumps in a relatively short time if happy. Sometimes sold under the name “mokasin” in Europe. USDA zones 3-6.
parviflorum v. pubescens x kentuckiense – this hybrid occasionally occurs where parent species ranges overlap. Treat as you would either parent. This hybrid has been remade artificially and is registered under the name C. Lothar Pinkepank. Recently plants have become available in the trade. USDA zones 4-8.
passerinum – easily grown in cold climates, but nearly impossible even under cool temperate conditions. Due to this it is not commonly offered or grown, but at the same time can be found in collections in both North America and Europe. Apparently indifferent to soil conditions if grown cold – neutral to acidic soils are both fine if the drainage is good. Totally intolerant of hot, humid summer conditions. USDA zones 2-4, perhaps the coldest parts of 5.
plectrochilum – supposedly slightly easier to grow than its American cousin C. arietinum. Plants today remain mostly wild sourced. More and more though, lab propagated plants are making it into the trade. Grow it much like other Cyps of western China: inorganic based mix, neutral pH, and protect from winter rain. Probably best to grow in pots since it is such a small species and easily subject to injury. Not easy to grow long term. USDA zones 5-7, maybe even 8.
reginae – this one is perhaps even more widely grown and produced than C. parviflorum v. pubescens. This species is very easy in cooler climates, but cannot tolerate overly hot summers even if the winters are cold. “Dirty sand” from old inland dunes works very nicely, but the pH should be adjusted to right about neutral. Really though, any good free draining mix of neutral pH should do just fine. These plants can get huge in time and the roots spread very far, so pot culture is unlikely for the long haul and beds need to be big. While this species does grow in wetlands in the wild, this is not the best choice in cultivation since rot can be a problem. Some people grow them in artificial bogs, the so called “Holman type” bog garden. A good species to start with. USDA zones 3-6.
segawai – widely grown in scattered collections throughout the world. This rare plant was exported from its native Taiwan in fairly large numbers until recently. Currently it is nearly extinct in the wild. It seems to be grow-able, but not easy since it is such a dwarf plant. It probably likes a well draining compost with moderate organic matter. Being a dwarf species, it needs to be looked after carefully and pot culture is recommended. Occasional plants are offered here and there, but it mostly remains very difficult to obtain. That could change in the coming years since it is now being lab propagated by a number of people. A choice rarity. USDA zones 6-7.
shanxiense – this plant is rarely available in the trade. Occasional wild plants are offered and even a few seedlings have made it to the market. It seems to be quite touchy in cultivation however. Given its wide range across north central China to Manchuria (and even a dislocated population on Hokkaido), it seems indifferent to particular conditions. Probably it should be handled like C. calceolus, but with less emphasis on lime based soils. Very likely it will remain an unusual specimen in most collections. USDA zones 4-6.
sichuanense – another highly desirable spotted leaf species that defies cultivation. There are no good reports of this one stabilizing in the long haul, at least from wild sources adults. Seedlings are now being offered in Europe, so perhaps like C. lichiangense, this little beauty will eventually become established, at least among expert growers. Grow like C. lichiangense, and cross your fingers. USDA zones 5-7.
subtropicum – this species remained unseen for years until new colonies were found in Yunnan. The type site in for the species in Tibet was destroyed in a flood. In 2010 photos started showing up on the internet of this rarity. With a few months wild collected plants began showing up on online auctions. The buyers, whoever they may be, are saying little about them. I know of one case where seed was successfully germinated (the flowers have high seed set, and so might be autogamous), and other rumors of successful germination exist. A number of plants that have been sold as this species turned out to be an Epipactis instead or the more common C. henryi which are said to cohabit with this species in Yunnan. Cultivation requirements remain unknown. Unlike any other Cyp this one is a true evergreen plant with each growth, including the leaves, persisting for up to two seasons much like a Calanthe species. It is found in frost free regions in the deep shade of thick, subtropical forests. Highly sought after, expensive, and legally questionable, this plant remains a near ghost to all but a few who have seen it in the wild or possess one. USDA zones 9 and higher.
tibeticum – widely grown, but fairly rare in collections, especially in North America. All adult plants available are wild sourced currently, with some subadults from seed available from a very few sources. Seedlings in production and should become more available in time. This plant is grow-able, but more difficult than C. macranthos. Grow it in inorganic based compost and protect from winter rains or it will rot utterly. Unfortunately still hard to obtain legal, adult specimens. USDA zones 3-6.
x ventricosum – a widely grown natural hybrid between C. calceolus and C. macranthos. This plant is to this day largely available through plants that have been collected from the Chinese/Russian border in both Manchuria and adjacent parts of Siberia. Some lab produced seedlings are coming available each year too. Fortunately it is very easy to grow, even withstanding warm to hot summers provided the winters are cold. Grow as you would C. parviflorum varieties. Some forms are very possibly the most beautiful Cyps in cultivation. Look for choice selections of this one to become more available in the coming years. Due to the great variation in flower characteristics, this plant has been given many names in the past, the most common ones being C. manchuricum and C. barbeyi, and while neither name is accepted by science, both are commonly used in the horticultural trade. USDA zones 4-7.
wardii – exported in some number to Europe and even a few to America. Most probably died within a short span. Not much being said about existing plants in cultivation. Everyone I know who has tried to grow them from wild sourced plants has eventually failed with them. I have seen specimens being grown by Hengduan Mountains Biotechnology, Ltd., so perhaps they will be offering plants in the near future. Rumor out of Europe is that more are being produced by Camiel de Jong as well. Probably best grown in near neutral pH with protection from winter rains. USDA zones 5-6.
x wenqingiae – rare natural hybrid of C. tibeticum and C. farreri. Recently produced artificially (registered as C. Wenqing) and have been coming to market as seedlings so far. It should be a bit more easy to grow than its parents, but with similar cultural needs. USDA zones 4-6.
wumengense – enigmatic species that very likely is a form of C. margaritaceum. Known only from the type collection material now deposited in an herbarium. Not found in Cyp collections, but no doubt someone is offering wild plants under this name – what people won’t do to turn a buck.
yatabeanum – a close cousin to C. guttatum, but thankfully more heat tolerant, growing nicely in cool temperate climates that get long winters. It should be grown in a free draining, medium acid compost such as perlite (or sand) and composted pine duff. In high latitude areas it can be grown even in sun, but further south locate it in bright shade with some morning sun. Not often available, but widely grown nonetheless. Seems fairly easy and will clump in a relatively short time if happy. USDA zones 3-6.
yunnanense – a difficult to grow member of the C. macranthos complex. Seedlings are available on the European market, but have proved difficult to grow. Some wild plants are undoubtedly circulating. Cultivation the same as with C. tibeticum, but a bit more difficult to grow, at least so far. USDA zones 4-6.
So that’s it for now. As time goes on and new discoveries are made and new break throughs in propagation are achieved, I will update this list (Note: both parts I and II updated as of August, 2013 – I’ll check back again soon!)