The se­cret of or­chids

Manitoba Gardener Magazine - - FRONT PAGE - Story and photos by Joan Por­te­ous

Or­chids make up one of the big­gest fam­i­lies of flow­er­ing plants. They have re­cently re­placed poin­set­tias as the most pop­u­lar pot­ted plant world-wide. With their as­ton­ish­ing beauty and mag­nif­i­cent colour­ing that give us as­ton­ish­ing con­trasts and a never-end­ing range of tones, they make very pop­u­lar plants to grow and en­joy in our homes. Scents can range from de­light­fully aro­matic to fleet­ing and barely no­tice­able, and bloom­ing pe­ri­ods can last sev­eral months.

Epi­phytic or­chids com­prise the vast ma­jor­ity of trop­i­cal or­chids avail­able for pur­chase in com­mer­cial green­houses and or­chid-spe­cialty out­lets. Most or­chids grown in the home are epi­phytes or air plants. This type of or­chid makes the best house­plant and af­fords much sat­is­fac­tion and plea­sure.

Or­chids have a unique plant struc­ture. By un­der­stand­ing how the plant func­tions, one can as­so­ciate the cul­tural con­di­tions re­quired in or­der for the or­chid to thrive. Their re­quire­ments for light, mois­ture, hu­mid­ity and fer­til­izer can be dif­fer­ent from com­mon houseplants, but dif­fer­ent does not nec­es­sar­ily mean dif­fi­cult!

Or­chid Growth

Or­chids have two ba­sic growth pat­terns: sym­po­dial growth orig­i­nates from a lat­eral shoot from the rhi­zome so the plant spreads in a hor­i­zon­tal direc­tion, monopo­dial growth orig­i­nates from a ter­mi­nal shoot and the plant grows in a ver­ti­cal direc­tion. This is an im­por­tant con­sid­er­a­tion when you are di­vid­ing and re­pot­ting your or­chid.

It's im­por­tant to un­der­stand the prin­ci­pal fea­tures of epi­phytic or­chids, in­clud­ing roots, pseu­dob­ulbs and leaves, when con­sid­er­ing grow­ing them in the home.

Roots

Roots of any plant play an im­por­tant role in an­chor­ing the plant as well as in pro­vid­ing nu­tri­tion. Or­chid roots

also per­form func­tions that in­clude stor­age, res­pi­ra­tion and even pho­to­syn­the­sis. In sym­po­dial or­chids, the roots de­velop from the rhi­zome lo­cated just un­der the sur­face of the grow­ing medium, and in monopo­dial or­chids the roots emerge from the stem and of­ten grow at right an­gles to the leaf. The health­ier the roots, the greater the po­ten­tial to gather min­er­als, salts, and mois­ture from the en­vi­ron­ment. In sum­mary, a healthy or­chid starts with healthy roots.

Or­chid roots have a cov­er­ing of grey-green dead cells called ve­la­men that cover the whole root and are found be­hind the green grow­ing tip of the root. Ve­la­men soaks up mois­ture very quickly and also plays an im­por­tant part in res­pi­ra­tion as it al­lows the plant to take up oxy­gen as the ve­la­men dries. If ve­la­men is soaked with wa­ter too long it un­der­goes bac­te­rial fer­men­ta­tion and will be de­stroyed. In or­der to main­tain healthy roots it is im­por­tant to have a suf­fi­cient in­ter­val between wa­ter­ings, good drainage for the pot and a grow­ing medium that pro­vides ad­e­quate aer­a­tion of roots in­side the pot.

Pseu­dob­ulbs

Many or­chids pro­duce pseu­dob­ulbs or false bulbs, which grow above the sur­face of the grow­ing medium from the rhi­zome ev­ery year. Leaves and flower spikes emerge from the pseu­dob­ulb, which is made up of fi­brous ma­te­rial that can store a great deal of mois­ture and en­ergy. Pseu­dob­ulbs, found in many dif­fer­ent shapes and sizes, are the long­est liv­ing part of the or­chid and will sur­vive in a leaf­less, dor­mant state for a long pe­riod of time. In or­der to main­tain healthy roots it is im­por­tant to have a suf­fi­cient in­ter­val between wa­ter­ings, good drainage for the pot and a grow­ing medium that pro­vides ad­e­quate aer­a­tion of roots in­side the pot.

Leaves

Most or­chids grow a rel­a­tively small num­ber of leaves in a wide va­ri­ety of forms. Leaves can be suc­cu­lent and be­come a stor­age or­gan for wa­ter. Leaves con­tain tiny open­ings on the un­der­side called stom­ata that can open widely when the tem­per­a­ture rises to al­low evap­o­ra­tion and cooling and pre­vent an ex­ces­sive in­crease of in­ter­nal tem­per­a­ture. Nar­row cylin­dri­cal leaves, such as those of a Vanda or­chid, do not store heat ef­fi­ciently so the plant will thrive in di­rect sun­shine and a warm en­vi­ron­ment. Some species of or­chids are de­cid­u­ous. Their leaves will turn yel­low and drop to leave a leaf­less pseu­dob­ulb which can act as a stor­age or­gan for new shoots.

Leaf struc­ture and ap­pear­ance are in­di­ca­tions for or­chid cul­ture. The thicker the leaf, the less of­ten the plant re­quires wa­ter­ing. If leaves are de­cid­u­ous, the plant will re­quire a rest pe­riod. If leaves are ten­der and per­sis­tent, the plant re­quires un­in­ter­rupted wa­ter­ing. If leaves are cylin­dri­cal, the plant can be ex­posed to long pe­ri­ods of full sun.

Grow­ing Or­chids In­doors

Grow­ing or­chids in­doors re­quires at­ten­tion to light, tem­per­a­ture, hu­mid­ity, air move­ment, wa­ter­ing and type of grow­ing medium.

Light

Dif­fer­ent types of or­chids have dif­fer­ent light re­quire­ments, rang­ing from low, to medium and high; how­ever, all or­chids grow and bloom best in as much light as they can tol­er­ate with­out burn­ing. Plants with thick leaves are slow to burn and plants with thin leaves burn more eas­ily.

The best lo­ca­tion for grow­ing or­chids in the home is the bright­est spot, and win­dow-sills of­ten pro­vide ideal lo­ca­tions. East-fac­ing win­dows are ideal. South-fac­ing win­dows re­ceive bright light for most of the day, but grow­ers should use cau­tion in sum­mer be­cause the bright light may burn plants. Sheer cur­tains will help to dif­fuse light dur­ing the sum­mer. West-fac­ing win­dows may work well and a north-fac­ing win­dow may work for an or­chid that re­quires low light. The direc­tion the win­dow faces is only a gen­eral in­di­ca­tion as to the qual­ity of light it of­fers as some win­dows are shaded by out­door plants, build­ing over­hangs, etc.

When or­chids are re­ceiv­ing a cor­rect level of light, their leaves will be a medium olive green and the pseu­dob­ulbs will be firm and full. Leaves on or­chids re­ceiv­ing too much light may be scorched or have a yel­low­ish or red­dish tinge. Too lit­tle light may be demon­strated by dark green leaves and soft or shriv­elled pseu­dob­ulbs.

Many types of or­chids thrive un­der ar­ti­fi­cial light­ing. Con­sider ad­just­ing the length of light dur­ing the day to co­in­cide with the sea­sons, as some or­chids come into flower only with pe­ri­ods of longer day­light.

Tem­per­a­ture

Or­chids are adapted to tem­per­a­ture fluc­tu­a­tions. With­out day/night fluc­tu­a­tions of ap­prox­i­mately 10 de­grees, the plant may grow well, but does not flower. Cool night­time tem­per­a­tures al­low them to store the car­bo­hy­drates re­quired to pro­duce flower spikes. Essen­tially or­chids may be clas­si­fied into warm, in­ter­me­di­ate or cool grow­ers. Warm grow­ers pre­fer 26 to 32 de­grees C dur­ing the day and 18 to 21 at night. In­ter­me­di­ate grow­ers like 21 to 26 de­grees C dur­ing the day and 5 to 18 at night. Cool grow­ers thrive at 15 to 21 de­grees C dur­ing the day and 10 to 13 at night.

Be alert for hot drafts from elec­tri­cal mo­tors or cold drafts from open door­ways, etc.

Hu­mid­ity

Most or­chids like a day­time hu­mid­ity of 40 to 70 per cent. Hy­grom­e­ters are quite re­li­able to mea­sure hu­mid­ity in your grow­ing area. Plac­ing plants on wa­ter-filled trays of peb­bles is an ex­cel­lent method of in­creas­ing hu­mid­ity sur­round­ing a plant. En­sure the wa­ter level is not high enough to sat­u­rate the bot­tom of the plant pots. There are a va­ri­ety of hu­mid­ity tray de­signs avail­able.

Plants are ex­cel­lent self-hu­mid­i­fiers when they are ar­ranged in groups. Mist­ing pro­vides hu­mid­ity for a short time but should not be ap­plied to the or­chid blooms. Mist­ing in the morn­ing al­lows the plant to dry be­fore night­fall and dis­cour­ages the growth of mold on damp plants.

Air Move­ment

All or­chids love gen­tle air move­ment as it helps to reg­u­late plant tem­per­a­ture, al­lows plant roots and leaves to dry, and it dis­cour­ages the growth of mold and other plant pests. Air move­ment pre­vents cool air pock­ets from form­ing next to win­dow panes in win­ter. Many homes have ceil­ing fans at­tached to light fix­tures, and these work very well. If us­ing a small por­ta­ble fan, aim the fan away from the plants and al­low the air be­ing pulled into the fan to cir­cu­late among the plants. The air com­ing out of the fan will dry out the plants. Gen­tle breezes help to re­duce pests and en­cour­age healthy growth.

Wa­ter­ing and Fer­til­iz­ing

Over­wa­ter­ing is the most com­mon cause of or­chid root loss. Af­ter wa­ter­ing, the grow­ing medium will re­tain hu­mid­ity for hours and even days, pro­mot­ing good root growth and health. Al­low plants to drain. The wa­ter­ing sched­ule will de­pend on the type of grow­ing medium, pot type and size, tem­per­a­ture, sea­son, amount of air move­ment, type of or­chid, etc.

The smaller the pot size, the higher the tem­per­a­ture. The coarser the grow­ing medium, the lower the hu­mid­ity. The greater the amount of air move­ment, the more of­ten wa­ter­ing will be re­quired. Wa­ter­ing may be needed weekly or more of­ten.

Rain wa­ter is ideal for or­chids. The qual­ity of tap wa­ter varies in dif­fer­ent ar­eas. Essen­tially tap wa­ter with an ex­cess of chlo­rine, or which has been ar­ti­fi­cially soft­ened or con­tains high amounts of cal­cium may harm the or­chids. Wa­ter should be room tem­per­a­ture and wa­ter­ing should be done in the morn­ing, so the plant’s leaves and shoots have time to dry be­fore dark.

Or­chids do bet­ter with too lit­tle fer­til­izer than too much. The rec­om­men­da­tions for fer­til­iz­ing vary from source to source. It is agreed how­ever that or­chids should be fed with a weak di­lu­tion of fer­til­izer. If us­ing a gen­eral fer­til­izer, quar­ter strength is rec­om­mended. Flush­ing the grow­ing medium with clear wa­ter will help to re­move any ac­cu­mu­lated fer­til­izer salts from pre­vi­ous ap­pli­ca­tions.

Con­tain­ers and Pot­ting Medium

Or­chids should be grown in as small a pot as pos­si­ble as long as there is space for the roots. Over­pot­ting leads to over­wa­ter­ing with sub­se­quent root rot. Pots with good drainage are es­sen­tial. Plas­tic pots are light­weight,

easy to clean and rel­a­tively in­ex­pen­sive. Clay pots dry out more quickly, are not light­weight and are more ex­pen­sive. Wooden bas­kets al­low space for root growth, but do not hold mois­ture well. Or­chids may also be mounted on slabs of bark to demon­strate the way they would grow in the wild.

Or­chids should be re­pot­ted ev­ery cou­ple of years, when the pot­ting medium starts to de­te­ri­o­rate, when the or­chid looks like it is be­ing stressed or when the plant needs to be di­vided. A wide va­ri­ety of pot­ting medi­ums are avail­able. Dif­fer­ent types of medium work for dif­fer­ent home en­vi­ron­ments.

An ideal or­chid medium should al­low air to cir­cu­late and wa­ter to flow freely around the roots. It should with­stand de­com­po­si­tion for as long as pos­si­ble and pro­vide struc­ture onto which the roots can ad­here, and it should dis­cour­age the growth of mi­crobes. Sphag­num moss may be used by it­self or more of­ten as an ad­di­tive to other pot­ting medi­ums. It has an­ti­sep­tic and vi­tal­iz­ing prop­er­ties and holds mois­ture longer than some other medi­ums.

Fir bark is avail­able as a fine, medium or coarse grade. Gen­er­ally, the smaller the di­am­e­ter of the or­chid roots, the finer the grade of bark that should be used. Or­chids with large roots do well in a coarse bark mix­ture.

Char­coal ab­sorbs acids and is a com­mon in­gre­di­ent of pot­ting mixes. It also col­lects salts that are dis­solved in wa­ter. Per­lite helps the medium to re­tain wa­ter and it does not de­grade. Many com­mer­cial or­chid pot­ting mixes are made up of a va­ri­ety of these prod­ucts. Other medi­ums are avail­able in­clud­ing clay pel­lets which hold mois­ture and do not de­grade. It is good to ex­per­i­ment to find the pot­ting medium that works best for your grow­ing con­di­tions.

Or­chid cul­ture in the home is a very at­tain­able goal. Choose a plant that will thrive in your home en­vi­ron­ment. Suc­cess can be achieved by un­der­stand­ing your plant’s char­ac­ter­is­tics, pro­vid­ing suit­able light­ing and im­ple­ment­ing a few el­e­men­tary pre­cau­tions as de­scribed here to achieve spec­tac­u­lar re­sults. Keep try­ing un­til you find what works for you. Once you have mas­tered the cul­ture of a spe­cific type of or­chid (and you will), it is time to try a dif­fer­ent va­ri­ety.

Joan Por­te­ous is the pres­i­dent of the Man­i­toba Or­chid So­ci­ety. Part one of a two part se­ries. Next is­sue: What or­chids to shop for.

Pha­laenop­sis or­chid.

Den­dro­bium pseu­dob­ulb.

Or­chid root.

On­cid­ium pseu­dob­ulb.

In­creas­ing hu­mid­ity.

Cat­t­leya or­chid.

Den­dro­bium Ag­gre­ga­tum.

Paphio­pe­dilum or­chid.

Or­chid pot­ting medi­ums in­clude fir bark, sphag­num moss, char­coal, per­lite and clay pel­lets.

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