GROWING SLIPPER ORCHIDS HAROLD KOOPOWITZ HE­VARIOUS­GENERA that­make­up­the­slipper should­ be­ small­ diameter­ particles­ in­ the­ range­ from orchid­sub-family­tend­to­have­different­cultural 1/4­to­1/2inch­(6-12­mm)­in­size.­ Trequirements.­ Of­ the­ genera,­ Selenipedium does water:­ Mexipediums,­ like­ all­ slipper­ orchids,­ prefer not­have­a­history­of­cultivation,­mainly­because­most good­ quality­ water­ with­ a­ low­ salt­ content.­ Many of­the­species­tend­to­grow­too­tall­for­most­conserva- growers­use­deionized­or­reverse­osmosis­water,­and­it tories­ or­ greenhouses.­ Cypripedium, Mexipedium, is­worthwhile­investing­in­some­type­of­water­purifica- Phragmipedium, Selenipedium are­ primarily­ terrestrial tion­system.­Small­handheld­water­testing­meters­are plants­while­many­of­the­Paphiopedilum species­are­epi- useful­as­they­allow­one­to­keep­an­eye­on­the­water phytic,­ lithophytic­ or­ terrestrial.­ We­ will­ deal­ with quality­one­is­giving­to­the­plants.­Good­water­quality Mexipedium first,­ and­ then­ Phragmipedium and should­ be­ less­ than­ 40­ ppm­ (parts­ per­ million)­ dis- Paphiopedilum together­ as­ many­ of­ their­ requirements solved­solids.­Many­reverse­osmosis­and­ion­exchange are­similar. systems­ produce­ water­ with­ less­ than­ 10­ ppm­ dis- Many­gardeners­seem­to­forget­that­plants­are­living solved­solids. creatures­and­need­to­carry­out­all­of­the­functions­that Because­mexipediums­are­desert­plants,­one­might animals­also­require.­Plants­must­breathe,­feed,­drink, be­apprehensive­about­the­amount­of­water­the­plants grow,­and­reproduce­as­well­as­other­functions.­As­is are­able­to­handle.­While­they­tolerate­drier­conditions the­ fate­ of­ higher­ living­ organisms,­ plants­ also­ die. than­the­other­genera,­I­found­that­they­seem­able­to Your­job­as­a­gardener­is­to­make­it­as­easy­for­the­plant handle­the­damper­conditions­of­the­greenhouse,­and to­continue­living,­growing,­and­flowering­for­as­long no­ provision­ need­ be­ made­ for­ growing­ them­ under as­possible.­Slipper­orchids'­cultural­ease­is­attested­by drier­ conditions­ than­ paphiopedilums­ on­ the­ same the­fact­that,­for­150­years,­they­have­been­one­of­the bench. most­popular­groups­of­orchids­and­are­grown­all­over the­world.­I­will­not­discuss­cultivation­of­cypripedi- temperature range:­This­species­grows­well­and­flow- ums­as­I­have­no­experience­with­those­delightful­flowers. ers­ under­ intermediate­ conditions.­ I­ grow­ it­ with­ the Much­of­this­article­has­been­copied­from­my­book same­ temperature­ regime­ as­ other­ tropical­ slipper Tropical Slipper Orchids,­but,­as­it­is­now­out­of­print,­I orchids­with­low­temperatures­of­55°F­(13°C)­and­highs will­ reproduce­ parts­ of­ the­ chapter­ on­ culture­ in­ this of­90°F­(32°C).­There­is­usually­a­minimum­high-low article. temperature­oscillation­of­20°F­(11°C)­on­a­daily­basis, although­it­can­be­higher­depending­on­the­season. Growing Mexipediums feeding:­Mexipedium plants­respond­to­a­well-balanced fertilizer­applied­at­strength­of­about­750­ppm­applied There­is­only­one­species,­Mexipedium xerophyticum, once­or­twice­per­month. and­it­comes­from­arid­regions­in­Mexico.­Only­a­few plants­have­ever­been­found­in­the­wild,­but­fortunate- hygiene:­As­with­all­slipper­orchids,­one­should­main- ly­it­has­proved­easy­to­grow,­flower,­and­propagate.­It tain­ good­ hygiene.­ Remove­ all­ dead­ leaves­ as­ they is­almost­trouble-free­and­appears­to­be­very­resistant occur;­keep­pots­free­of­weeds;­remove­any­leaves­that to­the­various­rots­that­can­attack­other­slipper­orchids. might­ look­ infected,­ etc.;­ however,­ Mexipedium seems Given­the­correct­conditions,­this­species­is­a­vigorous to­ be­ especially­ resistant­ to­ most­ insect­ and­ fungus grower. problems. containers:­ The­ hobbyist­ needs­ to­ make­ a­ decision Special conditions:­Mexipedium xerophyticum produces whether­to­grow­this­plant­in­a­small­two­inch­(five­cm) wiry­runners­between­their­fans­of­leaves.­These­run- plastic­rose­pot­(somewhat­deeper­than­most­two­inch ners­vary­between­one­and­six­inches­(2.5­–­15­cm)­in pots)­ or­ in­ a­ larger­ diameter­ container.­ I­ have­ grown length­and­each­ends­in­a­fan­of­leaves.­Another­runner and­flowered­them­in­both­small­rose­pots­as­well­as will­often­be­produced­from­the­base­of­that­fan­before relatively­ larger­ shallow­ pots­ with­ a­ diameter it­produces­its­own­roots.­This­often­leads­to­an­untidy approaching­ six­ inches­ (15cm).­ They­ seem­ to­ grow mass­of­runners­hanging­over­the­edge­of­the­pot.­The equally­ well­ in­ either­ plastic­ or­ clay­ containers.­ It­ is runners­ can­ be­ gently­ bent­ and­ twisted­ so­ that­ the quite­ surprising­ that­ these­ small­ plants­ lend­ them- emerging­ fan­ of­ leaves­ is­ confined­ within­ the­ pot. selves­ so­ easily­ to­ growing­ into­ fine­ specimens­ with Pieces­of­metal­wire­can­be­bent­into­an­inverted­“U” multiple­growths­and­flower­stems. and­ the­ runner­ pinned­ onto­ the­ compost­ of­ the­ pot close­to­the­base­of­the­new­fan­leaves.­Or,­if­you­wish, growing medium:­I­have­seen­them­succeed­in­a­vari- an­additional­pot­of­fresh­medium­can­be­placed­under ety­of­different­media­ranging­from­pure­bark­to­more the­emerging­fan­of­leaves­and­the­fan­pinned­to­the complicated­ mixtures.­ I­ use­ my­ standard­ paphiope- new­pot­until­roots­have­emerged.­Do­not­sever­the­rhi- dilum­ mix­ (see­ below).­ These­ plants­ have­ wiry,­ thin zome­until­a­new­root­system­has­become­well­developed. roots­ and­ it­ seems­ appropriate­ that­ the­ potting­ mix 216­­ Orchid Digest, Oct.,­Nov.,­Dec.­2012 Growing Paphiopedilums and first­be­scrubbed­clean­in­soapy­water­and­after­rinsing, they­must­be­submerged­in­a­bucket­of­water­to­which Phragmipediums a­ cup­ of­ household­ bleach­ has­ been­ added.­As­ many Many­aspects­of­the­culture­of­these­two­genera­are pots­as­can­be­fitted­comfortably­in­the­bucket­can­be similar­ with­ a­ few­ distinct­ differences­ depending­ on processed,­ however,­ resist­ the­ possibility­ of­ stacking which­ species­ is­ involved.­ I­ will­ start­ off­ with­ some tight-fitting­pots­in­the­solution­as­one­need­to­insure general­comments­and­then­consider­some­of­the­dif- that­the­bleach­comes­in­contact­with­all­surfaces.­The ferent­requirements.­Paphiopedilum and­Phragmipedium pots­should­remain­in­this­solution­for­about­one­hour, orchids­are­grown­in­many­different­parts­of­the­world. and­ then­ rinsed.­ The­ sterilizing­ solution­ is­ good­ for Their­popularity­suggests­that­they­are­robust­and­easy about­a­day.­I­prefer­plastic­pots­because­they­are­inex- to­ maintain.­ For­ the­ most­ part,­ both­ species­ and pensive­so­that­I­do­not­need­to­recycle­them.­When­one hybrids­are­quite­long-lived.­Some­individual­cultivars considers­that­the­value­of­a­slipper­orchid­plant­can­be have­probably­been­in­continuous­cultivation­for­well up­ to­ hundreds­ of­ dollars­ for­ one­ individual,­ saving over­100­years­and­75­years­is­not­uncommon.­During half­a­dollar­by­recycling­a­pot­is­a­false­economy­that this­ time­ they­ have­ lost­ neither­ their­ popularity­ nor does­not­make­sense,­and­I­have­neither­the­time­nor their­allure.­We­probably­grow­them­more­successfully the­need­to­devote­to­those­activities. now­ than­ at­ any­ previous­ time,­ but­ their­ continued potting media recipes:­ There­ are­ many­ different­ pot- popularity­ tells­ us­ that­ they­ are,­ in­ fact,­ very­ easy­ to ting­mixes­and­they­have­changed­and­varied­over­the grow­ and­ even­ beginners­ can­ succeed­ with­ them.­ Of years.­People­are­always­anxious­to­try­out­a­“better” course,­ there­ are­ some­ “difficult”­ species­ that­ are­ not medium.­The­act­of­repotting­into­any­half-way­reason- recommended­for­the­beginner­and­these­will­be­dis- able­ mix­ usually­ initiates­ a­ growth­ spurt­ in­ a­ slipper cussed­elsewhere. orchid.­After­repotting­in­any­new­mix,­many­people containers:­The­major­categories­of­suitable­containers report­on­how­well­their­plants­are­growing­and­so­oth- are­clay­and­plastic­pots.­There­seems­to­be­little­use­of ers­try­this­new­mix.­But­after­five­to­six­months,­the ceramic­ or­ glazed­ pottery.­ Usually­ clay­ is­ better­ for plants­ tend­ to­ slow­ down;­ the­ telling­ time­ is­ nine places­ with­ high­ humidity­ but­ plastic,­ being­ cheaper months­to­a­year­after­repotting.­I­canvassed­a­number and­ lightweight,­ is­ now­ used­ nearly­ everywhere. of­ slipper­ enthusiasts­ who­ are­ good­ growers.­ They Certain­plastic­pots­have­an­inverted­cone­in­them­to grow­ under­ quite­ different­ growing­ conditions­ and­ I allow­air­into­the­center­of­the­pot.­While­some­grow- asked­them­for­the­recipes­of­their­mixes.­Some­of­these ers­ get­ good­ results­ with­ these,­ I­ have­ seen­ equally are­listed­below­and­will­give­the­grower­a­feel­for­both good­ results­ using­ normal­ pots.­ It­ does­ not­ seem­ to the­ similarities­ and­ differences­ that­ occur.­ One­ com- matter­if­one­uses­round­or­square­pots,­but­the­square mon­ element­ that­ occurs­ in­ many­ of­ the­ North shape­allows­one­to­pack­the­pots­more­tightly­togeth- American­ mixes­ is­ Douglas­ fir­ bark.­ This­ comes­ in er­ on­ the­ bench.­ In­ the­ wild,­ many­ paphiopedilums nuggets­(pieces)­of­different­size­grades.­Small­nuggets grow­directly­in­the­humus­of­the­forest­litter.­A­num- vary­between­1/4­to­5/8th­inches­(0.6­–1.5­cm)­in­diam- ber­ of­ species­ are­ lithophytic­ growing­ on­ rocks­ with eter;­ medium­ nuggets­ vary­ from­ 5/8th­ to­ 3/4­ inches their­roots­foraging­in­a­very­thin­layer­of­mosses­and (1.5­to­2­cm).­Larger­sizes­are­also­available­but­normal- humus.­ Other­ species­ are­ epiphytic.­ Similar­ habitats ly­are­not­used­for­slippers.­In­recent­years,­pine­bark are­also­found­for­Phragmipedium species.­Irrespective imported­from­New­Zealand­has­been­substituted­for of­their­wild­nature,­most­slippers­do­well­in­pots­but Douglas­fir­bark.­It­is­said­to­have­better­lasting­quali- are­ difficult­ to­ grow­ mounted,­ and­ this­ is­ not­ recom- ties.­I­have­seen­many­fashions­come­and­go­in­potting mended.