Svante Malmgren         Henric Nyström

Orchid propagation

In the previous version of our website, we had different pages for species as opposed to hybrids. However, this separation is rather artificial for the garden grower. To be sure, some of us might be a little purist and just wish to collect and to grow species alone, whereas others care little about the names of the plants, as long as they are beautiful and grow well!

There is a great number of “wild” species of many genera that make good garden plants; tulips, roses, peonies and violets, for example, but consider what many years of improvement and selection through breeding and hybridisation have done to these genera.

We shall describe a number of Cypripedium species and hybrids that have been grown in gardens, some of them very successfully, some of them with great difficulty. With our own experience as a background, we will give some viewpoints and recommendations. In other countries with different climates, though, our recommendations might be only partly valid.

Within a few years, the experience of growing cyps in gardens will be widespread and in most cases you will gain a lot more information from a friend with a beautiful garden than from any issue of a flashy garden magazine, filled with photos and advertisement.

Beauty? – This is a question of personal preference and taste ...do you prefer a small flower or a large one? Which colour is best? Svante Malmgren generally favours big, red flowers such as roses, poppies and peonies ...and large red cyps!

Ease of cultivation? – This is a good basis on which to choose your Cypripedium. Some species are virtually impossible to keep alive in a garden setting for years (e.g. Cyp. acaule, and Cyp. lichiangense). Some plants are particularly sensitive to warm temperatures such as Cyp. guttatum. Some are very small like Cyp. bardolphianum and Cyp. plectrochilon. Cyp. kentuckiense is very tall and winter-hardy but seems to require a prolonged growing season that some northern climes may not deliver.

Legality? - Much illegal importation continues, especially from China – although some legal propagation and sale has started there too. When the iron curtain came down, Western Europe was flooded with “cheap” Cyp. calceolus plants from the east and these can still sometimes be purchased for a “suspiciously” low price from some nurseries. There are Cypripedium species that are probably not propagated from seed by anybody (yet), but they can still be bought via the Internet. “Our” European Cyp. calceolus is a borderline case when it comes to garden-growing. One the one hand it is easy to propagate from seed and easy to grow in the garden, but on the other hand it is very threatened in the wild and it can be impossible to determine the origin of a plant offered for sale. For this reason, we often use Cyp. calceolus for hybridisation rather than for sale and it often produces excellent offspring as a hybrid parent.

Cypripedium calceolus: As just described, this is strongly endangered in nature in many countries. However, it is easy to propagate from seed if sown half-mature approximately 8 weeks post-pollination (in Sweden). Adult plants that grow well in the garden can be fairly easily divided. As long as temperatures do not become too high even small plants are easy to grow on. It usually takes 7 to 8 years, though, from sowing to flowering. The species is being propagated for conservation projects in some countries.

There are several excellent Cyp. calceolus hybrids suitable for the garden. We have grown several to flowering size and others are growing on but have yet to flower. Mr Werner Frosch (the world champion of Cypripedium propagation) in Germany has raised yet more hybrids. All these crosses appear to share the hardiness of Cyp. calceolus flower 4 to 5 years from sowing and bear large blooms infused with colour from the other parent. We strongly recommend Cyp. calceolus hybrids for planting outside.

Cypripedium parviflorum is a close relative to Cyp. calceolus from North America. The flowers are significantly smaller than those of Cyp. calceolus and the colour of the lip is paler. It is, however, also a very good garden plant, and one that quickly divides. It, too, is easy to propagate from seed, sown mature and chilled after sowing.

Cyp. parviflorum is even better as a mother plant for hybridising, though. There are many excellent hybrids between Cyp. parviflorum and many other Cypripedium species. The flowers are usually very big, the plants strong and healthy and they grow on quickly. Like Cyp. calceolus hybrids, the flower colours may be a little variable and variegated if the parent plants bear blooms of greatly different colours. Probably the most marketed Cypripedium hybrid in the world is Cyp. Gisela produced by Werner Frosch; a hybrid between Cyp. parviflorum and Cyp. macranthos. Our best varieties of this hybrid are Cyp. parviflorum x rebunense, Cyp. parviflorum x tibeticum and Cyp. parviflorum x speciosum.

As previously discussed, though, the result of hybridising is VERY variable, depending on WHICH clone or species or subspecies has been used as the hybrid partner to the parviflorum plant. Some hybrids are weak, grow slowly or just don´t add anything new to the garden…

Cypripedium pubescens is another species from North America. It is rather similar to calceolus in size and colour, but there are many variable types. For us – and for some other propagators – it is trickier to propagate on a large scale from seed than parviflorum or calceolus. Hopefully, this problem will soon be solved.

Cyp. pubescens is also a very good hybrid partner and one well-known hybrid plant fit for the garden is Cyp. Aki from Werner Frosch; Cyp. pubescens x macranthos. We have grown a similar type; Cyp. pubescens x speciosum…but we propagate more hybrids with parviflorum and calceolus than with pubescens.

Cypripedium macranthos is a very variable species, depending where it grows within its range from Estonia in the west, to Japan in the east, Jakutia in the north and China including the Himalaya in the south. A British professor of botany has clumped them almost all together into one species; others prefer different names for different subtypes. Especially in China, there exist many different varieties. The provenance of particular individuals also means that some are rather easy to grow under certain climatic conditions in the garden, whereas others are more demanding.

Some of these varieties/species/subspecies are quite easy, but some are problematic to propagate on a large scale. Some grow well from seed and some don´t. In many cases the result is much better if two different clones/subspecies are crossed. It is hard to ascertain if this problem is just a question of inbreeding.

The seed germinates much better if sown half-mature. In Sweden approximately 8 weeks from pollination is the correct time. However, still it is rather difficult to buy artificially propagated plants of Cyp. macranthos on the market. It is likely that this will soon become much easier.

In order to propagate cyps within the macranthos group, in many cases we have used plants that were raised from the seed of a single self-pollinated plant that originated in Japan in 1980. This plant is still growing in the same garden in Denmark. It is a dark purple variant of Cyp. hotei-atsmorianum. Our first attempt at propagation from seed resulted in just a few plants developing, but growth was excellent, and the resulting plants produced very big, dark red flowers, which increased in number every year. These plants, however, are no longer self-fertile, and their pollen also behaves very poorly when used with other Cypripedium species. For this reason, we now cross-pollinate them with almost anything, not only other cyps with big red flowers, but also with pubescens, calceolus and fasciolatum. The viability of these hybrids is, as is usually the case with Cypripedium hybrids, quite variable depending on the other parent partner. The back-cross with pollen from the original mother/father plant also produced viable off-spring, but these haven´t flowered yet.

One of the strongest growing hybrids, Cyp. hotei-atsmorianum x tibeticum flowered for the first time early June 2009. It bore a very dark red flower, like French red wine. 200-250 plants of this hybrid have been raised and sold the last few years, and we now re-sow it almost every year. The hybrid with Cyp. macranthos also looks promising and will probably flower in 2010.

It seems very likely that before long several good clones or hybrids of Cyp. macranthos will be quite commonly offered on the market, with different clones grown by different propagators. Only time will show which of these not only look nice, but also behave well in a garden setting. The species is fairly easy to grow in the garden – so look out for it!

Cypripedium macranthos alba is a “true” white subtype, producing white-flowering off-spring. We have managed to raise it in a somewhat limited numbers from seed, the main problem being a shortage of the seed itself.

Cypripedium rebunense originates from the Japanese island of Rebun. As far as we know, there is just one flowering clump growing in northern Europe where it has been for many years. Formerly, there was also one plant in Norway and on one occasion the plants were pollinated but then this Norwegian plant died. The remaining plant is unfortunately not self-fertile …but we do have a limited number of seedlings growing on. Perhaps these might be useful as pollen parents in the future.

However, the pollen from the one remaining Cyp. rebunense plant has been used on several occasions for hybridising with very good results; the best cross so far is Cyp. parviflorum x rebunense. Surprisingly, a plant with a plain yellow lip crossed with one with a weakly coloured yellow lip has produced a flower in variegated colours of red and yellow! The hybrid is also very strong, and has consistently bloomed 3 years after sowing. We have raised it from seed many times.

We also have crossed Cyp. rebunense with Cyp. macranthos alba …while waiting for our own Cyp. rebunense to flower.

Cypripedium tibeticum is also quite a variable species. It is sometimes short at just 10 cm high, but sometimes reaches up to 40 cm. It bears extremely big flowers frequently of an almost blackish-red colour, but its lip could be regarded as clumsy in shape. It can be found without too much difficulty on the Internet and at least on some occasions may be of legal origin! We have encountered a few problems propagating it from seed, but we have used it many, many times as a pollen donor when hybridising. The hybrids usually grow excellently and produce very big flowers of dark red colour. They also divide much more often than does the species and many of them make very good garden plants.

Cypripedium corrugatum and Cypripedium smithii are similar species.

Cypripedium fasciolatum originates from the Himalaya, but nowadays can be bought as seed-propagated plants as well. Vegetatively it is rather short, but the flower is one of the biggest in the genus Cypripedium. The colour is a rather pale, whitish yellow. It has been used as a hybrid parent by Mr Werner Frosch with very impressive results. Examples include Cyp. fasciolatum x kentuckiense , Cyp. fasciolatum x macranthos and Cyp. fasciolatum x calceolus. All are amazing plants with extremely large flowers and we, too, are raising some of these hybrids on a large scale.

Cypripedium ventricosum is a very variable species, similar to macranthos, but generally about half the size. It can be grown in gardens like Cyp. macranthos. We have tried propagating it from seed on a couple of occasions, but none of the plants proved to be self-fertile.

Cypripedium kentuckiense comes from North America. A tall plant, with very big flowers, the petals of which can grow up to 12 cm in length! We find it quite easy to propagate from seed as do several other propagators – but growth on soil here in Sweden is not as vigorous as we had expected and hoped for. Year on year increase in size is not great and the plants seem to need a very long growing season. The seed capsule of a hand pollinated plant doesn’t produce a mature seed until the middle of November!

Werner Frosch has also raised some amazing hybrids using Cyp. kentuckiense, including Cyp. kentuckiense x calceolus, of which we have many seedlings growing on. Hopefully they will be hardier than kentuckiense itself! Our version of Cyp. kentuckiense x tibeticum exhibits great vitality, and has a very big flower – but its colour is a little too variegated for Svante Malmgren´s taste.

Cypripedium cordigerum from the Himalaya is rather uncommon as a garden plant, but it is easy to propagate from seed nevertheless, if sown 9 weeks from pollination (in Sweden) using half-mature seed. It has a rather small flower, but a sparkling white lip.

Cypripedium flavum from China and the Himalaya is quite variable in size, shape and colour. It has hairy leaves (like Cyp. reginae), is easily propagated from seed and is easily grown in the garden. An interesting observation is that the flower colour of an individual plant can vary from year to year, having yellow petals one year and brown petals the next! Although easy, the flowers are rather pale for somebody who prefers big, showy, red blooms!

It is, however, a very good hybrid partner in some cases. It can be hybridised with seemingly every other Cypripedium, but the vigour of the hybrids is quite variable, depending on the other hybrid partner.

Probably the most vigorous Cypripedium hybrid of all, though, is Cypripedium Ulla Silkens (Cypripedium flavum x reginae). Using Cyp. flavum as the mother plant, as we usually do, it produces approximately 4 000 seeds in a capsule, there is 100% germination from mature seed and usually 100% survival in soil too. The plants increase by division even before they flower, quickly producing large clumps, which will grow in almost any type of soil, as long as the situation is not too warm. The leaves are hairy and can withstand quite strong sun, but the flowers are prone to be burnt by strong sunshine. Cyp. Ulla Silkens is probably the second most popularly sold Cypripedium hybrid in the world (or possibly now the most frequently sold one…). It is the perfect Cypripedium for the beginner!

As far as other Cyp. flavum hybrids are concerned, Cyp. flavum x fasciolatum has flowered and is a strong, vigorous plant but its flower colour is a little pale as, of course, is that of its parents. Other hybrids we have growing on are x formosanum, x tibeticum, x corrugatum, and x wardii, but these grow slowly from year to year, not a very good genetic property!

Cypripedium reginae from North America is not an uncommon garden plant. It is one of the few Cypripedium species that in nature prefers a lower pH and, according to garden hand-books, more peat in the soil than most other Cypripedium species. But there are no exact rules for growing garden plants; we grow it in soil with a neutral pH along with the other cyps, and have seen it growing very well in gardens even on alkaline, lime-stone soil.

The very long roots grow very superficially, like the spokes of a wheel and can easily be damaged if you try to move or divide the plant. The species is very easy to propagate from seed, and the young plants grow on quickly. We rarely propagate it nowadays, and prefer the hybrid with Cyp. flavum. The hybrid takes all the best features from reginae and is taller, stronger and more vigorous.

There are reports of many other different hybrids with Cyp. reginae. We know very little about their vitality and their suitability as garden plants. We have raised Cyp. reginae x lichiangense from seed but it took 8 years from sowing to flowering …and the flower is not very exciting.

Cypripedium guttatum is a delightful little plant with a lip of red and white. It is very easy to propagate from mature seed, easy to grow, as long as you can give it a cool place in your garden. It takes five or six years from seed to a flowering plant. In the wild, in most instances, it grows north of the Arctic Circle in Alaska, Russia and Siberia, but there is also a Chinese type which can tolerate heat a little better perhaps; we are testing both types. The “Arctic” type has the bad habit of producing next year´s shoot 8-10 cm away (in any direction), but it also increases quickly by division. The Chinese type “stays” where you plant it.

Cypripedium yatabeanum is a close relative of Cyp. guttatum. It is a little taller, has a slightly bigger flower and increases very quickly by division, sending long shoots underground. The colour of the flower is brown and green, maybe not too exciting, but the plant is easily grown in a garden. We have hybridised it with Cyp. guttatum – a hybrid also known from the wild.

Cypripedium californicum has no need at all of the sun and heat of southern California. It grows in mountainous areas of northern California and Oregon and is very hardy even in very cold winters. The single flowers are very small, but a spike can carry up to 10 flowers!

It is easily propagated from mature seed, but needs 6 years from seed to flowering size.

(For the orchid propagator, it is a priori very tempting to hybridise the multi-flowered Cyp. californicum with other big cyps. Imagine a spike with 8-10 big macranthos flowers… We haven´t done this, but we have seen the result of Cyp. californicum x reginae and Cyp. californicum x flavum by another propagator. The plants look just like a Cyp. californicum – bearing on the top ONE SMALL reginae or flavum-looking flower…)

Cypripedium acaule grows in dark, dense pine-woods in North America on extremely acid soils where the pH can be as low as 4.5! In the wild it sometimes grows in very large numbers, but it is almost impossible to keep alive in almost any garden, whatever you do. It is very easy to propagate from mature seed but our plants died in soil a few years later.

Cypripedium japonicum and Cypripedium formosanum come, as the names tell you, from Japan and Formosa/Taiwan. It follows that they prefer a warmer climate than that of Sweden, more especially they need an earlier and warmer springtime than we can provide in the garden. If grown in a frost-free greenhouse, they will bloom in March. In England and other countries with a similar climate, such as some parts of Denmark, they can be successfully grown in gardens.

We have made the hybrids, Cyp. japonicum x calceolus and Cyp. flavum x formosanum. They are growing in the garden but their vigour and rate of growth are not very exciting. It is 6 years after sowing and still the latter has not flowered. We do not plan to repeat the crossings.

Cypripedium farreri, Cypripedium bardolphianum and Cypripedium lichiangense are a number of rare species from the Himalayas. You might find them for sale on the Internet but only very rarely are they artificially propagated. Cyp. farreri is rather easy to grow in the garden, but on our first attempt we failed to propagate it from seed even if they germinated well. Cyp. lichiangense is quite easy to propagate from mature seed …but very difficult to keep alive in your garden.

Cypripedium hybrids, like almost all orchid hybrids are sterile if self-pollinated. However, many orchid hybrids might produce seed if pollinated with the pollen from a true species. On some occasions they produce just a seed capsule without seed, sometimes with exceptionally few seeds, sometimes with 10 to 100 seeds. This is inadequate for large scale propagation, even if some of these secondary hybrids seem to show great vitality and we have a number growing on, just for the sake of curiosity. So far, Cyp. pubescens x speciosum x tibeticum has flowered (in 2009) and Cyp. Ulla Silkens x macranthos very likely will do so in 2010.

In the text, we have with few exceptions just mentioned species and hybrids propagated by ourselves or that we have experience of growing in our gardens ( i.e. including a number of hybrids from Werner Frosch). On the Internet there is a now very long list of Cypripedium hybrids, raised by different propagators, but as we have mentioned earlier, FAR FROM all of these are GOOD garden plants. Just a limited number of them is propagated in larger numbers for commerce.

In the selection of Cypripedium species and hybrids for your garden, do not only look at a nice photo on the Internet; consider if it is easy to grow and if it is legal. In the future, growers’ experience and propagators’ hardships will finally gel into a number of amazing - and legal - cypripediums, suitable for your garden! Like with most other garden plants, the majority will very likely be hybrids and a few carefully selected clones of wild species. Hopefully as a result the wild plants can then be left alone!