Planting and Care of Cypripedium Species

Although native orchids have a reputation for being challenging to grow, we find that they are generally unfussy and long-lived, provided their cultural requirements are met. We cannot guarantee your success, but we offer the following advice based on practice, experience, and the wisdom of others who have been at this for a lot longer than we have. Be sure to read these instructions in their entirety prior to situating your plant in your garden or natural area.

WHEN YOU RECEIVE YOUR PLANT

We generally ship plants in the spring and fall. Bareroot plants will arrive wrapped in a slightly moist paper towel inside a zip-style freezer bag. If you cannot plant immediately, place the sealed bag in a cool, dark area (40 - 45 degrees), where it will keep for up to several days. A refrigerator will work as long as it’s not too cold. Freezing will kill your plant, so keep it near the front or perhaps in the crisper. When you are ready to plant, carefully remove your orchid from the bag and gently unwrap it. You will see a bundle of roots extending from the center shoot(s). Fall-shipped plants have entered dormancy and may or may not have leaves still attached. Sometimes the leaves are dried and brown. These can be left in place until they naturally wither and detach. The condition of the top growth is unimportant. The roots and shoots have been inspected prior to shipping and should be in excellent condition. These hold your plant’s future potential, so be very careful when handling.

SITING

Most Cyps appreciate a few hours of direct morning sun followed by high, dappled shade for the remaining part of the day. Too much sun, especially when the young plants are becoming established, can be fatal. Too much shade and the plants will decline over time. Generally, the farther north you live, the more sun a species is likely to tolerate. Observe your site throughout the year and at various times during the day to determine the ideal spot. The east side of a home, fence or wooded area are often good candidates. Consider providing temporary sun protection until your plant is established. This can be done by attaching some 70% shade cloth to a frame above the plant. We've successfully used cheap tomato cages wrapped with inexpensive black window screen. This approach provides the additional benefit of excluding animals. (See below)

SOIL

Lady's slippers thrive in that elusive soil that is "moisture-retentive, but free-draining." Unless you are fortunate enough to have such native soil (and few of us are) you will likely have to amend your garden soil prior to planting. Loose friable materials such as composted pine bark, coconut coir, very course sand, or limestone grit can all be acceptable components. A commercially available, bagged mix, such as MetroMix 560 SunCoir, amended with limestone grit, can be a good alternative to the do-it-yourself recipe. One successful orchid grower recommends a homemade mix of three parts perlite to one part coconut coir. Avoid bagged mixes that are substantially composed of peat.

If you have heavy, clay soil, you can accommodate your orchid by using rocks or landscape timbers to create a planting bed that is above the soil line for better drainage. Remember: moisture-retentive, but well-drained. Your Cypripedium will not tolerate heavy soils that hold excessive amounts of water.

With the exception of Cypripedium acaule, most lady's-slippers prefer a circumneutral pH in the 6.0 – 7.0 range. Be sure to refer to species-specific notes below. If you’re unsure of your soil’s pH, contact your county extension office for advice. As a guiding principle, lady’s-slipper orchids are shallow-rooted plants. At maturity, the roots may radiate several feet or more, but they seldom penetrate deep into the soil. If you can provide soil to facilitate this growth habit, you will be on your way to success.

PLANTING

Keep in mind that terrestrial orchids are shallow-rooted. They grow with their roots radiating out from the shoots/stems, under the leaf litter and accumulated humus and are seldom more than a few inches deep.

Prepare the planting area by cultivating a 12-18” diameter circle of soil. Remove some of the soil so there is a “hole” about two inches in depth, tapering to a mound in the middle. To clarify, the perimeter of the circle should be roughly 2” deep and the center should be about even with the surrounding terrain. Carefully spread the roots out flat so that the shoots are on the mounded “peak” and the roots radiating outward. Now, gently cover with the amended soil, beginning at the edges and working toward the center. When you’re done, the tip of the growing shoot should be just below the soil line. Mulch the root zone with a 1” layer of composted pine bark, shredded leaves, or similar material, taking care not to cover the shoots. Water well and mark your orchid’s location with a surveyor’s flag or plant stake. (For fall planting, see WINTER PROTECTION, below)

FERTILIZATION

Most terrestrial orchids have low nutrient requirements and over-fertilizing can lead to leaf and root rot and eventual death. A light applications of water-soluable fertilizer during the growing season, from May through August in the northern states, can be beneficial. We’ve been successful using the Dyna-Gro® Gro product (7-9-5) at a rate of 1/4 teaspoon (1.2 mL) per 2 gallons (7.6 L), applied at every OTHER watering. Alternately, a time-release fertilizer, such as Osmocote, may be used. Less is more.  If you are in doubt, don’t fertilize. Observe your plants and see how they do. Deep green leaves indicate a healthy plant. Ligher, greenish-yellow leaves may indicate a nutrient deficiency.

PREDATORS AND PITFALLS

Like any young transplant, your orchid will be susceptible to a variety of threats from insects, small (and large) mammals, and other pests. Lady's-slippers are not delicate by nature, but because they are shallow-rooted, they must be monitored closely until they are firmly rooted.

If slugs are a problem in your garden, use a commercial slug bait located near your plantings. Small mammals can be kept at bay by configuring hardware cloth, especially during the winter months. Larger mammals, like raccoons, will need more emphatic measures. An inverted tomato cage, wrapped with hardware cloth should be adequate to protect young plants. We have not experienced problems with insects or fungus here at the nursery, but if you experience such maladies, action may be warranted. A systemic fungicide and/or insecticide (eg. Sevin) are potential options.

WINTER PROTECTION

Your orchid requires a vernalization or cold period of at least three months with temperatures below 40 degrees. In native haunts, fallen leaves provide an insulating blanket during this time. To mimic this at home, add an inch or two of chopped leaves after the plants go dormant in the fall. Cover the root zone and more—perhaps 2-3’ in diameter. After the first hard freeze, add another few inches to stabilize the soil temps and prevent heaving and thawing. You want the mulch to be fluffy, not super-compacted. Avoid heaping mulch on the growing shoots. This will encourage rot and doom your orchid!

If rodents, deer, or other vermin are a problem, temporarily covering the orchids with poultry netting or hardware cloth may help. In the spring, as temps begin to rise, remove the mulch to allow the shoots to emerge. But don’t rush things. A late hard freeze can kill the emerging shoots. Once the shoots start emerging add-back a good layer of mulch to moderate summer soil temps and maintain soil moisture—but remember, keep it clear of the shoots.

DEADHEADING

It is important to remove spent flowers from your orchid to prevent seed pods. The chance that seeds will germinate is vanishingly small and dead-heading will ensure that the plant’s energy is fully reserved for healthy growth and not seed production.

Notes on Specific Species

CYPRIPEDIUM ACAULE

Cypripedium acaule, the pink lady's-slipper or moccasin flower, likes more shade than other Cyps. and demands, absolutely, acidic, nutrient-poor conditions. If your soil is not naturally acidic, it should be liberally amended with pine bark fines (small bark chip mulch) and sphagnum peat in a 2:1 ratio. Aim for a pH between 3 and 4.5. Anything much higher will lead to this species' demise. C. acaule also appreciates a seasonal top-dressing of pine needles. Irrigate only with rain or distilled water to which white vinegar has been added at a rate of 1 oz/gallon. Do not fertilize.

CYPRIPEDIUM CANDIDUM

Cypripedium candidum, the small white lady's-slipper, can be more challenging to grow than other species. It benefits from high shade when it is young, but mature plants will tolerate nearly full sun to prosper. Keep in mind that in its native habitat, "full sun" is almost always dappled by taller vegetation. The species likes an alkaline soil (pH between 7 and 8) so an annual top-dressing of crushed oyster shells or garden lime is beneficial. If planting in containers, oyster shells can be incorporated with the other media components, up to 25% by volume.

CYPRIPEDIUM KENTUCKIENSE

Cypripedium kentuckiense, the Kentucky lady's-slipper, needs a free-draining soil. It is the only North American species that grows in alluvial forests. (Cribb) Amend heavier substrates with sand or grow in raised beds with a pH around 6. It will reward you with an impressive display featuring the largest flowers of the genus.

CYPRIPEDIUM PARVIFLORUM VAR. MAKASIN

Both native varieties of C. parviflorum are relatively easy to grow. C. parviflorum var. makasin grows natively in moist places but is surprisingly tolerant of mesic conditions when cultivated. Provide evenly moist conditions and a pH in the 6-7 range and your plants should form impressive clumps over time.

CYPRIPEDIUM PARVIFLORUM VAR. PUBESCENS

Cypripedium parviflorum var. pubescens, the large yellow lady's-slipper, is generally easy to grow. In fact, it's a great species for beginners. It requires better drainage than var. makasin and pH between 6 and 7.

CYPRIPEDIUM REGINAE

Showy lady's-slipper will tolerate more sun than some other species—three or four hours of morning sun is ideal. It likes moist, neutral, or slightly alkaline soil, and regular fertilizing, especially as it matures. Top dress annually with crushed oyster shells or lime. This is among the largest of the hardy Cyps. Multiple plants should be spaced no closer than two feet apart and will grow into massive specimens.

FURTHER READING

Cypripedium Culture by Carson Whitlow is an excellent resource for cultural information from one of the pioneers of hardy orchid propagation.

"The Gardener’s Guide to Growing Hardy Perennial Orchids" by William Mathis, Ph.D. It is out of print, but can perhaps be found at your library or an online used bookseller, like Abebooks.

"Growing Hardy Orchids" by John Tullock is also out of print but is another good reference.

"The Genus Cypripedium" by Phillip Cribb is recommended for the slipper-obsessed. A thorough documentation of known species and very good cultural advice. Out of print and expensive, but worth the investment if you can find it.

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