Cypripedium (abbreviation: Cyp.) has been very popular among plant enthusiasts and can be considered to be a true "garden terrorchid". Their distinct flowers show the relationship with 4 other genera that are extremely sought after among orchid hobbyists in general: Paphiopedilum, Phragmipedium, Selenipedium, and the lesser known Mexipedium. They all belong to the Subfamily Cypripedioideae.
Cypripedium (lady's slipper orchids) are generally though winterhard plants -some occur in the the Alaskan tundra- that can be grown outdoor year-round in showy clusters of dozens of plants.
Please note that Cyp. species are readily available from commercial sources and hobbyists. Prices are sometimes high for a plant, but remember that most of them multiply steadily. Natural habitats have become stressed from over collecting and this is a genus which has proven to be difficult to re-introduce, partly due to continued poaching.
Species from the Section Trigonopedia are treated differently. They have one true leaf and an oversized bract, giving the impression of two opposing ovoid spotted basal leaves. The flower emerges on a very short stem and the plants grow in and around China.

The majority of species occur and prefer cool summers in elevated altitudes or forests. This should be kept in mind when choosing a place in the garden or greenhouse. Look up the individual species and decide from there whether it can take full sun or dappled shade on mid-day. Gardeners on Swiss hill slopes or between the Rocky Mountains of British Columbia will be able to grow them as weeds, but we're not all blessed with that surrounding. Winter average and maximum temperature plays an equal role in successful culture. Most of them require -5°C to trigger dormancy, if this is skipped they'll start the following season with a hangover. A freezer can do the job (from November/December to February/March), but this means culture in pots as they have rhizomes with long brittle roots…you can't dig them up every year so you should opt for large or XL-sized containers. In nature they grow from sea-level (Alaska and Siberia) to 5,000 meters (Himalayas). The elevation is inverse linked to the distance to the (hot) equator: closer means higher … temperature is really important. In the high altitudes the plants get large amounts of direct sunlight, it's not possible to emulate low temps and direct exposure to the sun in lower altitudes (where we live). For this genus temperature is more important than the number of hours of direct sunlight. In pot culture, the container shouldn't be placed in direct sunlight. You can reduce temperature of the roots by placing the pot in a larger terracotta one, filling the space with wet perlite or expanded clay. Evaporation will cool the roots down. A minority of growers cultivates in pots (mostly due to bad experiences), it is advised to try to establish them in raised beds or in a dedicated spot in the garden. Greenhouse culture is an option, but you'll have to do a bit of rebuilding to achieve an alpine greenhouse with plunge beds.
The crawling rhizome sends up a jet of flowers and leaves, the latter last until autumn and are often a spectacle on their own (Cyp. japonicum, Cyp. formosanum). Depending on the species the rhizome can grow from 1 to 20 cm per year, the speed in growth is often correlated to their division rate. These are all factors that you should evaluate before making the purchase or trade.
The basic rules for a good soil:

• constantly humid, but …
• no stagnant water, very good drainage
• airy
• no compaction
• should not be exhausted after a year.

The basic ingredients for culture are Pumice, washed expanded clay, sand, gravel, seedling bark, pine needles, (untreated!) wood chips and if you live near a large forest: some sandy composted soil from a forest floor (the smell is fantastic).
Cyps can be categorised in 3 groups for soil:

For this genus we ignore the symbiotic fungi, the soil we choose provides all the nutrients and a comfortable environment. You might want to test your soil with a test-strip for pH, available at your local chemist. If pumice is not available, you can use Turface MVP 1) (coarser and decays slower than Turface). Don't use peat to bring the pH down unless you're certain the plants can survive a wet soil, use pine-needles, bark, crushed oak-leaves or tropical orchid mix bark instead. Most commercially available bark is treated with nasty chemicals.
Cyp. acuale is probably the only true acidophile (pH = 6 - 6.5), Cyp. reginae and Cyp. formosanum are referred to as acidophiles by a number of sources but they appreciate basic soils in culture. The majority want a neutral soil. The bottom should be composed of minimum 5 cm of expanded clay (neutral pH) or silica grit (the others). You might have presumed we're just talking about soil for pot culture, but you'll also have to do this in the garden. Dig out the soil up to 50 cm deep and layer the bottom 15 cm with grit,sand and gravel for drainage, the soil on top of this is what you'd use for pots. Garden soils for Cyps should not contain as much organic material such as bark & leafmould as soil for potting them up. In the garden this will lead to soil compaction, in general organic matter that touches the rhizome is one of the reasons of rot - both in pot culture as garden culture. In nature the rhizome crawls between the boundary layer of a rocky or sandy base and an organic topsoil (humus).

Cypripedium calceolus community pot
Image copyright orchidoquebec, image provided by Webshots.com

Garden soil is more difficult to control than a pot, but stabler and is a large buffer for moisture. Pot culture, on the other hand, is 100% scalable and diseases like snails and bugs are easy to spot. Cypripedium species are rather large, so you should consider protection from strong winds. Most growers prefer to use garden culture, protecting the plants in winter by mulching. One of the arguments against pot culture is that plants tend to outgrow their container quite fast. Plants in pots also experience temperature swings: frost at night and thaw during day, which is not appreciated by the emerging shoot. This is why some grower overwinter them in a cold frame until spring. The cold frame is basically a ventilated glass shielding (a greenhouse of 30cm high) with a sand basin. The pots are buried in the sand to reduce fluctuations and isolate the rhizome from the most severe frosts.
Water with rainwater or reverse-osmosis water, you can use tap water only for the species that live in limestone habitats but you should leave it out a night to get rid of the Chlorine. Tap water should not be used for every watering as the roots can't stand the buildup of salts, most references will point out that tap water is not a valid alternative and they're right. Keep the medium damp at all times during active growth. In the winter-resting period the soil can go a bit drier. The resting period starts when leaves start to fade to yellow.
Use of fertilisers depends on the soil: If you use a lot of organic humus or aged manure (organic fertilisers like manure or urea are not advisable) you shouldn't add extra fertiliser. If the medium is on the inorganic side you can apply 5%-10% of a normal orchid fertiliser every three waterings. You should flush the pot first with an abundant watering to get rid of residues from the previous application. A lot of growers prefer to give mild servings by spraying foliage feed or mixing small amount of fish emulsion or osmocote in the soil.
Long exposure to direct sunlight will cause burn marks on most Cypripedium leaves. They can take a few hours in the morning and enjoy a bright spot of indirect light.

Cypripedium reginae emerging flowers Photograph © Wes Hanson

Cyps have a resting period between November and February, order plants before this period so they can be sent to you during dormancy. They'll normally arrive as a bare-root rhizome with a shoot sticking out. The roots should be pale-brown to brown, long and brittle, soft dark ones are dead and can be cut of. Vendors shouldn't cut or trim the roots if they want to stay in business, they should be kept intact and handled with care. Plants with cut root tips are most likely wild-collected and require special attention and foliar feeding for surviving the first year. The shoot is white or white/yellow with a greenish tip. Take care not to damage roots and shoot during handling. There is off course the chance of shoot bud damage due to mail-handling, snails, rodents or clumsiness. If the shoot is broken of you shouldn't expect new growth there. The older part of the rhizome normally has a number of dormant eyes, cut of the oldest part of the rhizome for a length of 3 cm (minimum,with roots attached) and wrap all the parts each in a ball of live sphagnum moss, mist with demineralised water. Put them in a bag in a fridge at 4 - 10 C and check every week, new shoots should appear. If the rhizome is long enough you can take several of these pieces. The same can happen in the garden or in a pot: shoots get tramped on or eaten of. Don't dig the rhizome up but leave it in the soil and treat it like a normal plant: watering, fertilisation and protection from heat and drought. The next year one or more young shoots should emerge. This is often the reason behind plants not emerging for a year: rodents or snails ate the shoot bud.
After planting, the tip of the shoot should just stick out of the surface, roots and rhizome are covered completely. C formosanum can abort growth if the tip of the shoot is covered. Water the medium gently with cold water, better a couple of mild waterings then one flushing to avoid compaction. Keep the soil humid but not wet. If you've planted in a pot, place the plants in a sheltered spot outside, growth will start with the first warmer days in spring. The shoots shouldn't be exposed to constant thaw and frost, initiate growth by gradual increase in temperature, e.g. by placing moving them out of the fridge into the garden after frost.

Cypripedium calceolus timelapse
© S. Zingel, image provided by the Swiss Orchid Foundation at the herbarium Jany Renz

After the peak of flowering, you'll get the impression that growth has stopped and nothing is happening. Nothing is further from the truth: underground new roots are forming, the rhizome is storing starches, new shoots are forming and this is the time when you should pay attention to watering. The soil shouldn't dry out, be very generous when watering. Make sure you have a good reserve of rainwater to flush the medium between applications of fertiliser. Provide shadow and maybe spray with water in the morning and evening during the hottest days. Depending on your climate, a handful of ice cubes in the bucket an hour before watering can do miracles.
So far we've just discussed pot culture and garden culture, but Cyp growers have adopted a technique which lies in-between: sunken box culture. In this case you use a polystyrene box (the kind they use for storing fish in ice) with a perforated bottom as a pot, but you place it in a square hole in the garden. This has a few advantages: the polystyrene creates a buffer against drought, useful when you want to plant your Cyps in the shade of a tree - trees can dehydrate the soil on dry summer days. Secondly you can easily move the box to a cool cellar or freezer in winter. It's also easier to repot and split plants. You could also do the same for plastic pots, but Cyps tend to outgrow them, boxes are larger.

Cypripedium californicum
Photographs by Scott361, under Creative Commons License

Naturally occurring where water is abundant in southwest Oregon (Siskiyou Mountains) and northwest California. One of its regular companion plants is Darlingtonia californica, which tells a lot about the soil requirements in habitat: sphagnum (with peat) and leafmould in contact with cool water to keep the roots cool in full sunlight, but not as winterhard as its insectivorous neighbour. Sources are contradictory on hardiness in culture: some report full winter-hardness in Scandinavia 2), others warn of damage in moderate winters… To be on the safe side protect them from frost, if you're in a region with strong winters you'll have to apply protection (mulching). Keep them in community culture, let the plants form dense clumps to create a -natural- show of small flowers. The rhizomes will start to divide from an early age, before flowering. Svante Malmgren reports that this species does not produce hybrids with other Cyps in the garden, but that it's relatively easy in IV germination.

Starts to flower in June and seems to appreciate mulching with aged manure and full sunlight. Young plants typically bear up to three flowers, established plants up to 12, but it takes minimum 6 years from seed to seed. pH between 5.6 and 7.5. This species has a reputation of being difficult in culture, experienced growers suspect that this has to to with the mineral serpentine which is dissolved in the water where this species grows.

Cypripedium reginae
Photograph copyright Itasca Lady Slipper Farm

One of the easier species in culture. The soil should contain a relatively large amount of organic material such as leafmould, use sand/grit for drainage but don't let the medium become dry. As it grows in wetter areas and near swamps it can take more water. The resulting soil should be slightly acidic, this can be achieved by adding small amounts of peat or slightly basic by adding limestone - not neutral for some reason. The intensity of labellum-color depends on the difference between day and night-temperature, if the night-temperature is allowed to drop the labellum will become deeper purple. You can also mix crushed limestone under the roots, growers report that the plants like it. Will outgrow containers rather fast.

Cypripedium calceolus
Distributed under GNU-FD Licence, donated by Mg-k

This species has been cultured for over a century, largely because it's one of the largest and showiest of Eurasian orchids. You might expect that this has created a low price and less stress from poachers, but nothing is less true. Cyp. calceolus populations are still being vandalised.
This species bares 1 or rarely two flowers with a yellow labellum and dark petals and sepals (lighter varieties exist). Plants get to 70 cm high and grows in calcerous, neutral or slightly acidic soils, but you should always add limestone gravel for drainage and local pH. This is not an ideal species for the first-time grower. In the wild you'll encounter it most in forest-clearings in a layer of leaf litter on a soil with good drainage.

Cypripedium japonicum
A woodland species from China, Korea and Japan

A showy species that resembles Cyp. formosanum to such a large extent that you'll often find the latter referred to as Cyp. japonicum var. formosanum. C. japonicum enjoys a far larger range however, being found from central China to Korea, and historically all of Japan. This species is much more difficult in cultivation than its Taiwanese relative. The soil can be either acidic or neutral in reaction, but must always remain moist. It is completely intolerant of dry periods. Growers report that it is difficult to bloom even after it has settled in, possibly due to the fact it grows too deeply into the media. One solution is to put a thick layer of sand below the plants such that the rhizome cannot easily "dive" deeper down. Like C. formosanum, it is a heavy feeder, requiring more nutrient than is normal for most Cyps. It can also grow for an extended period compared to other Cyps, staying green even through November if conditions permit. Like C. formosanum, it is quite heat tolerant (although it prefers cool conditions) and doesn't need cold winters to vernalize adequately. Three months of temperatures not exceeding 10ºC will suffice. Not recommended for pot culture since it likes to range. Not a beginner's plant.

Cypripedium kentuckiensis
Used with Permission, © Eric Hunt, www.orchidphotos.org

Perhaps the most heat tolerant species in cultivation due to its natural proclivity for living in lowland areas of the SE USA. Thankfully it is also quite easy to grow, being happy with most composts as long as they are free draining and nearly neutral (pH 6-7 is fine). Most sources state that it prefers sandy soils with some humus. It is a late bloomer, flowering even after C. reginae, and it also can be a late grower as well. Plants can remain green until mid November if they do not get frost. Remarkably it is very cold tolerant as well, capable of being grown in the northernmost states of the USA. A good plant for beginning growers.

Cypripedium flavum
Photoghraph © J.-D. Gerber, used with kind permission

From China, bearing 1 or rarely 2 flowers with a large yellow (sometimes red) spherical labellum of up to 5 cm diameter. Its habitat is forests, clearings and grassy coasts, typically found between 2500 and 3500 m altitude in limestone soils. It requires a mix that is extremely free-draining, pH slight basic to neutral and a minimum of organic material in a cool environment, a few growers report success with pure pumice. If you get everything right you'll be rewarded with many shoots.
Dr. Holger Perner, who has been studying and growing Chinese Cypripediums in China for a number of years now, has found that C. flavum in fact cannot endure average temperatures higher than 26°C for long periods. The plant seems to be unable to carry out basic metabolic functions and literally "starves to death". 3)

Cypripedium formosanum
Photograph copyright kevin1537, image provided by Webshots.com

A mountainous species from Taiwan, growing in forest clearings between 2000 and 3000 m near streams and sources. Considered to be an easier species, with 2 striking fan-shaped leaves and a vertically oriented labellum.
One of the reasons it's more forgiving is the relaxed requirement for cold temperatures, this species is actually sensitive to humidity during thaw and better fit for overwintering in the greenhouse or cold frame. Plants start their growth in February, from this period on they should be shielded from frosts as it'll damage the leaves and can cause the flowers to abort. A couple of months between 0C and +10C is sufficient for dormancy, given there are no long term spikes in temperature. Cyp. formosanum appears to like fertilising, give a 5%-10% dilution every 2 to 3 weeks from March till September with a pause in July and August.
This species is fit for growing in containers, but tend to form large clumps.

Cypripedium henryi
Chinese species from open forests or clearings on limestone soils, between 1800 and 2800 m. The plant normally bears 2 uniformly green flowers with a strong pleasant scent. Cultured in a free-draining medium with dolomite gravel, pumice, sand, a small amount of fine bark and forest soil it'll multiply readily.

Cypripedium macranthos (or macranthum)
Photograph copyright H.Perner, image provided by the Swiss Orchid Foundation at the herbarium Jany Renz

This species has a huge distribution extending from the polar circle to Taiwan, and bears a single large flower that ranges from dark purple to cream or white (var. album). The many variations in color-intensity have spawned a number of very nice stable cultivars, mainly available from Japan. Provide a slightly acidic soil that contains pumice and good drainage, keep on the cool side in summer. Growers report it can support warmer temps in summer, but keep and eye on them during the hottest days.

Photograph copyright Itasca Lady Slipper Farm

Cypripedium parviflorum, Cypripedium pubescens
From North America, these two species used to fall under the name Cyp. calceolus but have been separated from their Eurasian cousins. There is still debate whether Cyp. pubescens isn't just a variety of the variable Cyp. parviflorum, when looking for information you should consider looking for references on Cyp. parviflorum var. parviflorum and var. pubescens. Size seems to be the dominant factor in keeping them apart: Cyp. pubescens up to 80 cm, 10 cm petals and labellum 6.5 cm long. Cyp. parviflorum is the smaller one, up to 60 cm high and sepals/labellum half of Cyp. pubescens.
Culture is the same as for Cyp. calceolus, except that these plants want a slightly acidic soil, so replace the limestone by silica grit, add a small amount of pine-needles (especially for Cyp. parviflorum). Cyp. parviflorum appreciates higher soil-humidity than Cyp. pubescens.

Cypripedium x ventricosum
Where the habitat of Cyp. calceolus and Cyp. macranthos overlap (Siberia and Manchuria), this hybrid can be found. The plant has intermediate characteristics between its parents, flowers have a pleasant scent and plants are robust. Culture is closer to Cyp. macranthos, with the same preference for cool temps during hot summers. The hybrid has been copied by hobbyists and is available via commercial sources. The only difference: the artificial hybrid is called Cyp. Ventricosum, the natural one Cyp. x ventricosum.
Cypripedium candidum
Normally inhabits meadows on mesic soil (underground with natural water supply).This species loves calcerous soils, add extra crushed limestone and perlite to the mix. They can be planted in a position that takes full sun in morning and evening, providing you keep the soil damp - they can take more water than the average Cyp. They don't like hot environments. Apparently better suited for garden culture with inorganic soil (minimal amount of leafmould) than pot culture, they don't like replanting. If you get them established, the location will normally also be ideal for growing Gymnadenia conopsea.

Cypripedium himalaicum, tibeticum, smithii, corrugatum
Photograph of Cyp. tibeticum, copyright H.Perner, image provided by the Swiss Orchid Foundation at the herbarium Jany Renz

You won't encounter these in collections very often. You can consider them as difficult versions of Cyp. macranthos. Their habitats are the hostile cliffs and slopes of the Himalayas (2000 - 5000m) with long cold winters and short summers.
C. tibeticum seems more tolerant of higher temperatures (around 26°C), although not too high. According to Dr. Perner, this species is perhaps one of the easiest southwest Chinese species to grow (C. macranthos and its hybrid, C. x ventricosum from the northeast being easier still). 4)

Cypripedium irapeanum
From Mexico, this species has a long inflorescence (up to a meter) with large yellow flowers that open in succession. Apparently these plants grow in dry areas - peculiar for Cyps - and culture is still impossible.
Cypripedium fasciculatum
Not for the faint-hearted or beginners. Prefers a slightly acidic medium in a fast-draining soil. In their natural habitat they have a very short growing season followed by a hot and dry summer. Soil should be dry when dormant, but not bone-dry. Too much water wil initiate rot.

Section Trigonopedia
Cypripedium margaritaceum
Photograph copyright camilase, image provided by Webshots.com

Peculiar Section of species from China with two ovoid spotted leaves (one true basal leaf plus a large bract) and a single flower on a short stem. Not a lot is known about culture of these species. The rhizome should not come into contact with organic material or it will rot, use a mineral compost with a thin organic layer on top. The bottom should be fast-draining. Watering during active growth is not really problematic. Keep dry at +2C during dormancy, most failures are due to too much moisture at the beginning or end of the dormancy, it's difficult to get the timing right. Data on winter hardiness is scarce, Cyp. fargesii is hardy down to -20°C but only if there is a protective cover of snow and if the soil remains dry.
As a reliable rule of thumb: the more spots on the leaves, the happier the plant. Cyp. micranthum grows pure green leaves if the moisture is not to its liking, fargesii and sichuanenese will produce leaves with a reduced amount of spots. All species will only consider flowering when you get all the factors correct. Plants are very sensitive to being moved, dig them up only when it's necessary. They need an established root-system to flower, interfere with the roots as little as possible. There are reports that when planted in outdoor beds, roots from other plants such as cedar trees can disturb their growth. Once they have established however, the plants become less sensitive to fluctuations in treatment.
Species from this section shouldn't be imported from their country of origin. Better just send the money as a gift to a Chinese farmer and save the plant from certain death. The only way of establishing them in your collection is by contacting an experienced grower and convincing him you're experienced enough. These species don't multiply reliable and most don't want to set seed

Cypripedium margaritaceum
Photograph copyright Thomas

Cypripedium acaule by Eric Muehlbauer
The most important sign that C. acaule is amenable to garden culture is its presence as a native plant in the vicinity. If acaule has been sighted in the area, and, most importantly, the gardening area is typical of the environment and has not been altered by construction or landscapers, then cultivation should not pose any difficulty.
The author's garden is located in Cutchogue, on the North Fork of Eastern Long Island, in New York State. Except for a small lawn area and a rock garden, the property has not been altered by developers, landscapers, or the author. Most of the 200 x 50 foot property is natural oak- hickory forest, to which has been added rhododendrons, azaleas, and other shrubs, as well as assorted wildflowers and cultivated perennials. The native plants, consisting of oaks, hickories, mapleleaf viburnum (Viburnum trilobum), lowbush blueberry (Vaccinium angustifolium), Solomon's Seal (Polygonatum biflorum) and others have been left in place. The soil is almost pure sand, with a top layer of oak leaf humus. The pH is extremely acidic, 3.9, and very low in nutrients. (Table 1) Rainfall tends to be very scarce during the summer. While the summer of 1996 was unusually wet, more typical summers bring only a few centimeters of rain during June, July, and August. The most extreme was the summer of 1995, in which no rain fell at all between late July and mid-September.
The C. acaule planted in the garden were originally purchased as single growths, propagated by a company called The Wildflower Source. They were planted in mid-October, about ten and eleven years ago. One plant was purchased in the spring and placed in a pot, as it had already started growing. It remained in the pot for the summer, and was planted in October. The plants are sited under oak trees, where they remain in dappled shade for the entire day. However, the earliest stages of growth, between mid-April and early May occur in much brighter light, before the trees leaf out.
Other than a bloom on the pot-grown plant, the next season or two involved only vegetative growth.
Since then, the plants have continued to bloom every season in late May. Each plant puts up a minimum of five growths and four blooms.( Figs. 1 and 2) The flowers are large and very fragrant, especially in the afternoon. At least three flowers in each clump are pollinated every year, using pollen from the native plants nearby. Several pods are sent out to Spangle Creek and other laboratories for propagation, and at least one pod each year is allowed to ripen and disperse seed naturally. Contrary to other observations, these plants do not appear to be set back in their blooming by pollination and pod development. Perhaps this is due to the early harvest of most pods, usually in late August. However, several native plants are also pollinated each year, also without loss of blooms in the following season.
The plants require no special maintenance. They are not fertilized or treated with any chemicals. Except for occasional slug damage in early spring, they are free of any pests or diseases. This is in marked contrast to Cypripediums grown in New York City, where fungal diseases usually blast the buds of acaule and frequently kill both acaule and reginae. The lack of fungal disease may be due to the drier environment in Cutchogue. Orchids such as Platanthera and C. reginae grown in artificial bogs frequently show fungal damage in Cutchogue as well. Supplemental water is given during dry periods in order to ensure good production of viable seed. Formerly, the plants received no supplemental water, even during dry summers. The plants themselves showed no stress at all, but no viable seed was produced. Subsequent years with more water produced fertile pods with good quantities of seed. Well water in Cutchogue is normally soft and somewhat acidic. However, prolonged drought coupled with heavy agricultural water usage may result in a decline in water quality at the end of the summer. So far, the plants have been unaffected by any changes in the water. In fact, the acaules survived a period of salt intrusion entirely unscathed, while other plants such as Rhododendron viscosum and its hybrids, and Acer palmatum were burnt and completely defoliated.
The cultivated plants are more robust than the native plants in the vicinity. Most of the wild plants consist of only one to two growths, and the leaves are smaller than on the cultivated plants. The native plants generally bloom well, although only three plants flowered in 1996, the year following the severe drought. Like many wild populations of C. acaule, individual plants appear one year and disappear the next. However, the overall number of plants has remained fairly constant. They are on private land, and the owners are aware, and appreciative, of their presence.
Overall, as can be seen, Cypripedium acaule can be a very easy species to grow when it is provided with the right conditions. The best indication of the proper conditions is the presence of native plants in the vicinity, or at least a history of their having occurred there. While the first few seasons require a little extra care, in protection from drought and rummaging squirrels, once established they are care free, low maintenance plants that can be relied on to give a beautiful display every spring.

• Voles: a.k.a. field mouse or meadow mouse. They love to nibble at the roots. You can protect your plants in the garden by placing a metal wire mesh before filling the hole with compost.
• damping off
• insects: Cypripedium is sensitive to chemicals, try to control pests manually
• slugs: they nibble the tender shoots away in one night. Use slug pellets or sprinkle with Methaldehyd.
• Soil pathogens such as aggressive fungi can destroy a colony in a couple of growing seasons. There are no known effective cures - systemic or other - to stop this. The first signs are rotting at the base of the plant (not the rhizome), followed by collapse of the leaves. The only cure appears to be transplantation to pot culture for plants in the affected zone, replacing the soil and waiting a couple of growing seasons to screen out other plants. Keep the moved plants isolated: don't use communion water trays and clean your tools with alcohol between two plants. Place them back in the garden using sunken boxes for the first years. It's a lot of work but worth the effort.
• Potyvirus: a viral infection recognisable by brown streaks on the leaves and distorted growth of all parts of the plant 5). There is no cure but the disease can be tested in a lab. All infected plants must be destroyed as this infection is systemic. This disease will spread to other species and nearby plants if the diseased plants are not removed and destroyed.

Cypripedium calceolus In Vitro
Photograph copyright fcalmant, image provided by Webshots.com

It's common practise among Cyp. growers to buy flasked IV seedlings. This reduces the price per plant, you're sure they're not wild collected and you'll learn the growth cycles faster. Bare-root plants shipped by mail are more prone to shock than IV seedlings. Don't think that your plants will all be identical: Cyp. seedling flasks are normally seeds germinated in IV, not meristem clones, so you'll get enough variation to breed with. Seedling flasks with hybrids are even more unpredictable as you'll get deviations in color and size. There is a lot of variation between species in time it takes to flower.

Growing Cyp seedlings from flask
General Principles for Planting Cypripedium Seedlings
How to raise in vitro propagated Cypripedium seedlings to fully established hardy plants for the garden by Camiel F. de Jong PDF

Cypripedium 'Ulla Silkens'
Photograph copyright Mattias Winter, used with kind permission

Artificial Pollination of Cypripedium Species by Camiel F. de Jong PDF

The labellum is shaped like a hollow pouch and as with most orchids it functions as a landing platform. Although the pouch only has one opening, the folding of the rim creates the impression of two openings (from the insect's point of view). Inside the labellum are tufts of hairs oriented towards the exit, this forces the insect to move towards the exit. Escape along the rim is impossible: this is folded inwards and the insect can't get grip on it. When exiting the labellum, the animal has to pass via the column. This structure contains 1 central staminode and 2 lateral anthers with pollinea. Leaving the flower means picking up pollinea or depositing them on the stigma … this flower structure is a measure against self-pollination. Cyp. japonicum and formosanum have a variation on this theme, the entry of the flower is located at the front of the pouch and is clearly indicated with purple markings that contrast with the rest of the flower. Sun Haiqin of China informed Dr. Clark Riley that Cyp. japonicum is pollinated by an undetermined bumblebee 6)

Cypripedium fascicultum (clustered lady's slipper)
Diapriidae

Photographs on the left show the location of the opening for pollination on Cypripedium japonicum. The markings are anthocyanin pigments which brightly contrast with the rest of the labellum in both visible and UV-light. This works as a guiding beacon for bumblebees. The only way out is via the exit close to the column as in other Cypripedium species. The photographs clearly shows what looks like a "landing platform" on the front of the labellum, under the opening. The photographs were provided by Dr. Clark Riley, http://www.cyps.us

For a closer view of the path the insect must follow, take a look at the two cross-sections on your left. Cypripedium pubescens shows the classic labellum where markings guide the insect towards a ladder of thick hairs. In Cyp. japonicum these markings are more dominant and there are a lot of translucent windows. These windows can also be found on "classical" Cyp. flowers and are used to draw the insects attention away from the entry. Insects use spots of bright light to locate exits and the flower makes fake exits with these translucent patches to draw the animal away from the entry and lure it towards the exit. In Cyp. japonicum and formosanum the entry is much larger than in other species, this explains the need of a large amount of windows to compete with the light which can be observed from the entry opening. Without these there's a chance the insect will leave via the same way it entered the labellum, rendering the pollination strategy useless.

Propagation, cultivation and breeding of terrestrial temperate orchids, with focus on Cypripedium spp.
by Linda-Marie Rännbäck PDF

Frosch's Cypripedium info is the homepage of Werner Frosch, the emperor of Cyp culture
Cypripedium on the Terrorchid Forum
The SlipperOrchid Forum
The slippertalk Forum
Frosch's Cypripedium Forum (also in German)
Miniral nutrition for Slipper Orchid Growers
SlipperOrchids dot info

The Genus Cypripedium.
by Phillip Cribb
History, Ecology, Morphology, Biology, Distribution.
Amazon.com discription

Comparative rates of pollination and fruit set in widely separated populations of a rare orchid (Cypripedium fasciculatum)
by Lipow, Sara R., Peter Bernhardt, Nan Vance

Cypripedium taibaiense (Orchidaceae), a New Species from Shaanxi, China

Itasca Ladyslipper Farm is a young but growing Cyp farm in the U.S.A.
Frosch Cypripediums & U.S.A. distributor: www.hillsidenursery.biz
Robert's Flower Supply Frosch Cyps
Cyp haven
Spangle Creek Labs supply laboratory-grown seedlings
Raising Rarities

Below is a list of accepted names, for a full list with invalid names, click here