Phragmipedium Culture and Potting Medium Recipe
Phragmipediums are found in Mexico through South America. Most of the species of this group grow in a terrestrial manner. This may be either loose, forest litter or light, friable soils rich in organic matter. Plants can be found in light dappled shade to sometimes full sun. Rainfall is plentiful in these areas giving way to the common belief that the Phragmipediums should be grown wet. At Carter and Holmes, we have broken the Phragmipediums into two major groups. The first group consists of plants that are of an older type of hybridizing using species such as Phrag. caudatum, Phrag. sargentianum, and Phrag. longifolium. The second group consists of Phrag. besseae and Phrag. schlimi. These two groups are considered the “dry group” and the “wet group. We have found two distinct potting mediums are necessary to grow these different groups.
The first group of Phragmipediums can easily be potted with seedling grade fir bark type mixes, possibly with the addition of tree fern or charcoal for drainage.
The second or “wet” group has entirely different water requirements. We found that using more water in the fir bark mix to supply the moisture requirements for Phrag. besseae and its hybrids caused the bark to mold. We found that none of the standard Phrag. mixes suited our conditions. We modified a hobby mix used in the Midwest. This media has given the best results. The ingredients for this mix are as follows::
- Three parts long fibered New Zealand or Chilean sphagnum moss
(Soak for at least 24 hours, drain and squeeze out excess water)
- One part volcanic rockor ‘Dyna’ rock, rinsed (1/4" to ˝")
- One part #3 perlite (sponge rock)
- One part loose medium tree fern
We pot the plants loosely to allow for good drainage and air flow around the roots. Always make sure the newest growth is touching or slightly below the top of the medium. Unlike epiphytes, slippers will not grow ‘air roots’ and in order for the new roots to thrive, they must be in or directly on the growing medium. Repotting should be done when a new growth is showing and during the temperate seasons, spring or fall. Depending on how often watering is required and your summer temperatures (temperatures of 85 or higher break the mix down faster) repotting should be done every 12-18 months.
We use filtered or ‘reverse osmosis’ water to prevent brown tips from forming on the leaves. Bottled water or even water that is allowed to sit for a day before use can suffice. We have discovered that water containing excess chlorine is especially bad for these sensitive plants. Those growing in the sphagnum moss medium, like Phrag. besseae, or its immediate progeny, are best grown sitting in small saucers with perhaps a half inch or so of fresh water. When the water is almost used up, it’s time to water again. Do not allow the water to stagnate but instead flush the pot thoroughly 2-3 times per week.
To fertilize, use ½ strength Grow More 20-10-20 every fourth watering or Dyna Gro 7-9-5 every other watering. It is important to leach the pot of accumulated fertilizer salts every month, especially if using clay pots and saucers.
We have found our best growth comes in the fall and winter when evening temperatures are maintained as low as 58 degrees to 62 degrees. Ideal daytime temperatures would be 77 degrees to 82 degrees. Good air movement is very important. Like Phalaenopsis, do not allow water to sit in the crown of the leaves overnight or on cloudy days.
Bright, indirect light is good for adult, flowering size plants. Young plants of Phragmipedium should not be exposed to as much light as older plants.
Note: This guide is only applicable to Phragmipediums. For other varieties, please click on one of these links: