Lady’s slipper orchid (Cypripedium calceolus) is a widespread orchid that is named for the unusual shoe-like shape of its elaborate flower. Lady’s slipper orchid is pollinated by numerous species of bees.
I. Appearance and Characteristics
Cypripedium calceolus is a lady’s-slipper orchid, and the type species of the genus Cypripedium. It is native to Europe and Asia. It is typically found in open woodland on moist calcareous soils. In continental Europe it is also found growing in the decomposed humus of semi-shaded woodland cover on limestone. It has declined over much of the European part of its range, and as a result is legally protected in a number of countries. Its upper elevation limit is 2,100 meters (6,900 ft).
Cypripedium comes from the Greek Κυπρισ πεδιον (Kupris pedion), meaning Venus’ foot (a reference to the Roman goddess Venus). calceolus is Latin for a small shoe.
Cypripedium calceolus sensu stricto (“in the strict sense”) does not occur in North America. The closely related Cypripedium parviflorum and C. pubescens are often still referred to as subspecies or varieties of C. calceolus.
This is the largest-flowered orchid species in Europe, growing to 60 cm tall with flowers as wide as 9 cm. Before it flowers, it is distinguished from other orchids by the large size and width of its ovate leaves (as big as 18 cm long, 9 cm wide), which like other orchids exhibit parallel venation. Each shoot has up to four leaves and a small number of flowers (typically one or two), which have long, often twisted petals varying from red-brown to black (rarely green) and a slipper-shaped yellow labellum, within which red dots are visible. It is a long-lived perennial and spreads using horizontal stems (rhizomes).
Cypripedium calceolus can be confused, when not flowering, with Allium ursinum, Convallaria majalis or several species of Epipactis orchid. It closely resembles other species of Cypripedium orchid native to the United States (see taxonomy).
Chromosome number has been given as 2n=20 but also 2n=22.
Cypripedium calceolus is frequently associated with stands of hazel trees.
It is pollinated by a number of different insect species, including at least seven species of miner bee in the genera Andrena and Colletes, as well as at least two species of Lasioglossum (furrow bees). Plants are very vulnerable to herbivory by slugs and snails.
II. How to Grow and Care
Sunlight
Cypripedium calceolus is a woodland species, does not demand strong light, and prefers to be fully or partially exposed to the sun, but resists shady areas. It is good to enjoy the sun flower cooler hours of the day, but to have some shelter and can be grown on the north side of a building. If grown in a cold frame it should be covered by shade cloth in the summer.
Temperature
The plants can be grown outside in cold frames, and benefit from a cold winter. They are able to survive cooler temperatures throughout the year. They like daytime temperatures that range from 10°C to 18°C. They can tolerate slightly warmer temperatures, but the daily temperature shouldn’t exceed 26°C as it won’t tolerate it. During the nighttime, this orchid can tolerate temperatures that fall around the freezing mark of 0°C, but they do better with temperatures around 7°C.
Humidity and watering
Cypripedium calceolus like to be moist, but they won’t tolerate getting soaked on a constant basis. You don’t want to allow them to dry out either, and you should water them twice a week during the growing months from April through October. From October through the end of May, these orchids go into a dormant period where they require less water and fertilizer. You can cut back your watering to once a week with periodic checks to ensure they’re staying moist. They like humidity levels around 50%.
Soil
The “soil” required for lady’s slipper orchid is special because, as an epiphyte, it originally grew on big trees in tropical forests. You need to mimic this growing environment with, for example, water moss, wood chips, coconut shells, volcanic stones, or perlite as soil substrate. You can also buy orchid-specific soil directly from gardening stores.
Fertilizing
As soon as you notice new growth beginning at the start of the growing period, you should feed your orchid every 10 days with a diluted half strength balanced fertilizer. You can alternate this balanced fertilizer with a seaweed-based fertilizer every other feeding. When your orchid goes dormant, you can stop fertilizing them throughout their dormant period. They won’t need it until you start to see new growth in the spring, and then you can resume feeding your orchid every 10 days.
Planting Instructions
You do not need a large pot to grow a lady’s slipper orchid as it won’t produce a vigorous root system that occupies much space. If the pot is too large, the soil tends to collect water and cause root rot. The height of the pot should be 2.5 cm taller than the (pseudo)bulb of the lady’s slipper orchid. You can easily buy lady’s slipper orchid in a local gardening store and simply place it in breathable, well-drained substrate. After planting, use upright sticks to support flowering branches. In warm, humid climates, cover the root of lady’s slipper orchid with sphagnum moss and attach them to a tree with strings.
Pruning
It is best to prune wilted lady’s slipper orchid flowers promptly after blooming to reduce unnecessary nutrient consumption and promote more blooms. Trim withered and diseased leaves promptly to increase air circulation, thus reducing pests and diseases.
Propagation
You can propagate lady’s slipper orchid by division or by cuttings.
Propagation by division: using a lady’s slipper orchid with more stems is a better option for the division. You should do this after blooming. When dividing the plant, dig it up carefully with its roots intact, and cut the roots into several clusters from the base. Remember to use clean tools and disinfect the wounds with a fungicide. Then plant your divided clusters in containers and keep them in a cool place. While the new roots are growing, spray them with plenty of water to prevent them from drying out.
Propagate by cuttings before flowering. Choose a healthy, thick stem, remove the leaves, and cut it into small 2-node pieces. Insert the bottom directly into the substrate. Keep the substrate moist, and they will root and sprout in about 2-3 months. You can also propagate by cuttings by laying the entire stem on top of moist substrate, and cutting it into pieces after it roots and sprouts. Transplant those rooted cuttings into pots for further growth. A third way to propagate by cutting is possible during weather with high temperatures, when the stems develop roots, and you can cut them off and plant them.
III. Harvesting and Storage
If you want to display lady’s slipper orchid flowers in vases, harvest there are only 2-3 flowers blooming on the stem. Cut diagonally at the bottom of the flower stem, and place it in a vase immediately. You can enjoy the cut flower in clean water for about 14 days, or for a longer time with preservatives.
