2024 - Cultivation Tips and Climate Data
THE SECRET TO GROWING MEXIPEDIUM XEROPHYTICUM
Seong Tay
PAPH. illustrated, Volume 9, No. 5
May 2024
Last month the master of Paphiopedilums, Seong Tay shared valuable information about the care and cultivation of the solitary species in the Mexipedium genus.
The secret to growing Mexipedium xerophyticum
Determined to master the art of growing this rare species orchid, Seong has been researching extensively and perfecting his cultivation of Mexipedium xerophyticum. He believes they are easy to grow, when you have the facts about how they grow naturally.
HISTORY
Heriberto Hernández entdeckte die Art 1985 bei einer Untersuchung der regionalen Orchideenflora in Mexiko und sandte das erhaltene Material an das Herbarium der Mexikanischen Orchideengesellschaft.
Die in der Natur extrem seltene Art Medipedium xerophticum wurde ursprünglich nur an einem einzigen Standort im Tiefland von Ost-Oaxaca gefunden. Jahre später, im Jahr 1990, wurde die Kolonie durch ein Feuer stark dezimiert, sodass nur ein einziges Exemplar in der freien Natur übrig geblieben war.
Mexipedium xerophyticum wurde jedoch [2011] an einem nahe gelegenen Standort wiederentdeckt, und es wurden Pflanzen zur Vermehrung entnommen, um das Aussterben der Art durch Pflanzenjäger und Naturkatastrophen zu verhindern.
Nachzuchten dieser Pflanzen sind heute erhältlich, aber immer noch selten.
TAXONOMY
Mexipedium xerophyticum was originally called Phragmipedium xerophyticum. After DNA analysis by Albert and Chase in 1992, it was found to be genetically distinct from other slipper orchids and placed in a genus of its own, Mexipedium, named after its discovery in Mexico. The epithet xerophyticum refers to an adaption to dry desert-like conditions.
PLANT DESCRIPTION
Plants of Mexipedium xerophyticum are small about 15cm across. Mature plants have 5 - 8 leaves which are succulent, hard and thick and are structured to store water. Leaves are 12 - 18cm long and 1 - 3cm wide.
Flowering occurs after the previous season’s growths have matured.
Flowers are small and short-lived, white with pink staminodes, and are produced sequentially, 1 to 2 at a time on a raceme which may be branched, meaning a raceme may have several flowers open at the same time.
New growths are borne on long racemes which may quickly fill up a pot when the plant is well grown.
Propagation of Mexipedium xerophyticum have given rise to various cultivars.
TOP TIPS
Plants are relatively problem-free if certain precautions are observed:
- Use shallow pots.
- Well-draining potting medium with limestone chips.
- Do not allow potting medium to become acidic.
- Water with half-strength fertiliser solutions. Frequent watering in summer. In winter, water only when required by immersion in a dish of fertiliser solution.
- Avoid letting water on leaves in winter.
Once plants are established, they are relatively easy to grow, and they grow quickly during the summer months, spreading by stolons.
These notes are exclusively for the education of the members of the Paphiopedilum Society of NSW, Inc., on how to grow Mexipedium xerophyticum in Sydney. Environment conditions elsewhere may be different. Some of the photos used as illustrations are sourced from the internet and I thank the owners for their use.
IN THEIR NATURAL ENVIRONMENT
In its native habitat in Oaxaca at an elevation of 320 metres, Mexipedium xerophyticum grows on exposed vertical limestone rock walls with a northern exposure. Because of the northerly exposure in the northern hemisphere, the plants receive bright but no direct sunlight during the day. The change in weather conditions during the year can be quite extreme. During the summer months of June to September, there is abundant rain in the afternoons or evenings. Winter is extremely dry with hardly any rain from mid-winter to spring, therefore the requirement to adapt to the dry conditions by storing water.It appears that Mexipedium xerophyticum grows under intermediate weather conditions – maximum of 32 degrees C in summer and minimum of 8 degrees C in winter. There is abundant rainfall from April to October with hardly any rain during winter months of December to February. Humidity is relatively constant throughout the year at between 54% to 74%.
OAXACA, MEXICO, WEATHER AVERAGES
CULTURAL NOTES
Culture described is for Sydney conditions.
Light:
Bright light but no direct sunlight.
Medium:
Same as what I use for my Paphs, which is, 4 parts of good quality bark (Orchiata), 1 part of medium Perlite & 1 part of limestone chips (Selgrit).
Note: Mexipedium xerophyticum does not tolerate an acidic medium and limestone is required to counter any acid buildup. Limestone is calcium carbonate which reacts with any acid to produce a neutral salt.
Repotting with fresh medium is recommended every 2 to 3 years.
Seedlings and small divisions are very slow growing, but once they are established, they grow very quickly and spread by long stolons, thereby requiring repotting into larger and wider pots.
Pots:
Shallow pots are recommended. As plants proliferate, they are repotted into larger pots.
New growths develop from the ends of stolons and will not produce roots until they come into contact with the potting medium. Pin down the new growths or top up with potting mix.
Temperature:
In Oaxaca, maximum temperature is 32 degrees C, minimum temperature 8 degrees C. In Sydney, grow under intermediate temperatures between 10 to 30 degrees C.
I have experimented growing some of the plants without heating, down to zero degrees C, resulting in a few losses. Without heating, it is important to keep the plants relatively dry. Any water on the leaves and other green parts of the plant will result in wet (bacterial? or cold damage?) spots and demise of the plant.
Watering & Fertilizing
The wet season in Oaxaca is between April to October (late spring to early autumn) and very dry in December to February (winter). In Sydney, I water every 3 to 4 days during spring to autumn when night temperatures are above 14 degrees C and more frequently on very hot days and nights.
In winter, I try not to water Mexipedium xerophyticum unless indicated. When plants appear droopy, I dip the pot into a shallow (about 20-25 mm) dish of dilute fertiliser solution for a minute or two, watering from below. Half-strength Peters Excel fertiliser solution is used with every watering. In late spring, I scatter a few pellets of chicken manure like Dynamic Lifter on top of the potting mixture.
Humidity:
In Oaxaca, the humidity is relatively high throughout the year, even during the months with no rainfall.
Plants can cope without water during the drier but cooler winter months.
In Sydney, the humidity can be quite low during winter. If there is a need to water the plants, water from below and avoid wetting the green parts of the plants. Make sure there is good [ventilation].
Propagation:
Pollination is difficult as the pollen are very small and difficult to locate. It is easier to propagate by making divisions of the plant.