Cacti are generally associated with a desert environment, inhabiting the sandy ground of the hot arid areas of the United States and Mexico. But quite a number of cacti make their home in the rainforests of tropical Mexico and Central and South America. They are called epiphytic because they grow on other plants, although they are not parasites. In their native habitat, these epiphytic species often grow in the forks of trees or in rock crevices where their small, fibrous roots take hold in decaying vegetative matter and bird droppings. This light, loose medium allows water and oxygen to reach the plants’ roots, which absorb the moisture and dissolved nutrients. A few epiphytic species are rooted in the ground and use their aerial to climb up tree trunks. Because their root systems are relatively small, continually water-soaked soil will suffocate the roots. The jungle’s frequent rains are ideal for keeping plant roots moist but not saturated. High in the trees, the plants receive much-needed air circulation from shifting tree branches which also let in the dappled sunlight they need to produce blooms.
See Myron Kimnach’s article The Species of Epiphytic. Cacti in the Epiphyllum Society of America’s Directory of Species and Hybrids, Fourth Edition for a comprehensive description of epiphytic cactus species.
The material presented here will specifically address the planting and propagation media for the Epiphyllum species and hybrids, but can be generally applied to all epiphytes, bromeliads, orchids, etc. The concepts, ideas, and opinions expressed in this paper are based on three sources. The first source is the author’s experience in propagating around 500 hybrid epiphyllum varieties. The other two sources are the only books known to have been written bout the culture and propagation of the numerous epiphyllum species and their 10,000+ registered hybrids. The first of these publications is Scott Haselton’s book, Epiphyllum Handbook,* copyrighted by the author in 1946 and printed in Pasadena, California. The second book, Fine-Flower Cacti by F.R.McQuown was first published by Redwood Press Limited, Trowbridge & London in 1965. These two books provide help to those who have a newly acquired interest in epiphyllums to know and fully enjoy their plants.
POTTING SOILS– PAST AND PRESENT
Because the root system is limited, a rich soil is necessary to give them the required nutrition. A semi-acidic soil rich in nitrogen to approximate their natural habitat should be used. Haselton on page 57 of his book states that “you should never use lime for epiphyllums”. He believes that it is the desert (not jungle) cactus that require soils rich in lime, i.e. sweet or non-acid soils.
It is interesting to note the various soil mixtures, however, when comparing them, they all are quite similar. The number of different potting mixes is as diverse as the people using them. There are features that they must share: good drainage and aeration. The diversity in the mixes comes from climate, they type and shape of pots used, and the watering habits of the person caring for the plants.
One of the early growers here in the USA, Dr. R.W.Poindexter, found the following mixture satisfactory after years of experimentation (Haselton):
* 4 parts leaf mold
* 2 parts German peat moss
* 3 parts cow or sheep manure
* 2 parts gravel
* 2 parts sharp sand
One of the best-known early German growers and hybridizers, Curt Knebel, recommended (Haselton):
* 1 part leaf mold
* 1 part river sand
* 1 part peat moss
* 1 part crumbly loam
* 1 part rotted manure
McQuown gave this recipe for use in “nematode-free countries”:
* 60% leaf-soil (leaf mold)
* 25-40% garden soil
* 0-15% (unspecified) drainage material by volume.
To a bushel of this he added a
* 4-inch pot of bone meal
* 4 oz. sulfate of potash
Current recommendations are provided by some of the nurseries that specialize in epiphyllums. For instance, Rainbow Gardens suggested in their 1997-98 Plant Catalog the following epiphyllum potting mix for home preparation:
* 1 part leaf mold
* 1 part coarsely ground bark
* 1 part ¼” – ½” redwood or fir bark
* 1 part perlite or horticultural pumice
* ½ part horticultural charcoal
* ½ cup bone meal per cubic foot of mix
Jim Pense in his 1994-1995 Epi World Catalog suggests an alternative in addition to one similar to the Rainbow Gardens mix. It uses one part commercially packaged camellia-azalea mix, one part perlite or horticultural pumice, and one part small orchid bark. Both nurseries recommend that if one lives in an extremely humid area, Florida, the Gulf States, or Hawaii, to lighten the mix by increasing the proportion of perlite or pumice to leaf mold or potting mix
Cornell University developed two soil-less mixes for commercial growers– one of which is an epiphytic mix that can be easily adapted to home use (Backyard Gardener.com, “Potting Soil Recipes and Soil Reconditioning”):
* 1/3 bushel Douglas fir bark (finely ground)
* 1/3 bushel sphagnum peat moss (shredded)
* 1/3 bushel perlite (medium)
* 8 tbsp. ground dolomitic lime
* 6 tbsp. Superphosphate (20% powdered)
* 3 tbsp. 10-10-10 fertilizer
* 1 tbsp. Iron sulfate
* 1 tbsp. Potassium nitrate
Now what kind of potting mix do you use? Ask ten people and you will get ten different answers. How confusing!!! Here is my suggestion. Try the one most similar to your area, the coast, inland, amount of heat and moisture, etc. Try experimenting a little with your mix. The one thing everyone seems to agree on is that epis need media that drains well. Epis just don’t like wet feet. Now here are some of our members’ mixes:
Beth Jackson in Sorrento Mesa (San Diego, CA) purchases commercially available cactus mix. She mixes three parts cactus mix with one part perlite and one-half part oyster shell.
Irene Sias from Chula Vista, CA also uses cactus mix that she purchases from Home Depot. She uses two-thirds cactus mix, one-third perlite and tosses in a little sand and vermiculite.
Jill and Phil Peck in North Park (San Diego, CA) uses 50% perlite (#2 and #3) and 50% peat moss, with a little crushed charcoal and about 2-tsp. bone meal per seven-inch pot. They are experimenting with “Plant Success” (mycorrhizae– a beneficial fungi that helps roots absorb nutrients) and replacing peat with coir (both shredded and bark) but it is too early to see how that is working.
Roger & Sandra Chapin, in Rancho Bernardo, CA uses a combination of one part Coir (ground coconut husks), one part potting mix (see the attachment of its contents), one part 1/8 to 1/4 inch orchid bark, and two parts #3 perlite with a dash of blood meal and bone meal. This has produced some good results. I add a measuring cup of both blood and bone meal to a two-bushel tub of potting mix.
I have switched from the use of sphagnum peat moss to coconut fiber, Coir, for two reasons. Coir is a renewable resource and it re-wets readily when dry. The Coir is also not as acidic as peat moss.
|pH||5.4 – 6.8|
|Ash||3 – 6|
|Electrical Conductivity (uS/cm) max||250|
|Cationic Exchange Capacity (mez/100g)||60 – 130|
|Total Organic Matter (w/w, dry basis 5)||45 – 50|
|Organic Carbon (w/w, dry basis %)||20 – 30|
|Lignin (w/w, dry basis %)||80 : 1|
|Cellulose (w/w, dry basis %)||8 – 9 times|
|Carbon/Nitrogen Ratio||10 – 12|
|Water Holding Capacity (of dry weight)||94 – 96|
A direct comparison between Coir and peat is given in Dr. Geoff Cresswell’s paper “COIR DUST—A PROVEN ALTERNATIVE TO PEAT”. The following table from his paper compares the chemical properties of three peat-type materials available in Australia.