SEASONAL CULTURE
 Philip C. Tomlinson   © 1997
Wellington  New Zealand    

INTRODUCTION

Paphiopedilums are one the most popular of all the orchids grown in this country, and around the world. There are books devoted to just these plants, and there are even specialised clubs and magazines. Quite widely available from specialist orchid nurseries, they can also often be found in garden centers and similar outlets. They produce attractive and distinctive flowers, many of which are long lasting. Amongst the uninitiated orchids are commonly thought to be delicate plants requiring expensive growing facilities. Paphiopedilums include amongst their numbers those which are strong robust plants capable of surviving quite difficult conditions, although, of course, their growth and flowering will be much better and more assured when their relatively simple basic requirements are provided. There are, however, some paphiopedilums which are more delicate and which require additional care, but there are plants attractive to all covering a wide spectrum of growing skills and conditions. Most paphiopedilums require a glasshouse or protected growing area, although the facilities provided do not necessarily have to be expensive or extensive. There are some species and hybrids that can even be grown successfully with cymbidiums. They can also be grown in the home, in the bathroom, lounge or kitchen, on the refrigerator or TV or other suitable shelf, provided additional humidity is supplied through the use of a gravel tray or similar.
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Paphiopedilums will be grown in all parts of the country although in the colder environments, additional warmth and protection will be required, especially for the warmer growing varieties. In a general guide such as this growing information relevant to all areas cannot be discussed. What will be attempted is to detail the general growing criteria, and the reasons for the various recommendations. This should enable any individual to ascertain the general growing and seasonal requirements. It is, however, recommended that anyone new to growing orchids, or someone moving to a new area, contact a local grower to ascertain specific growing advice. In particular the members of orchid societies will be happy to assist with local information. Joining a society is the ideal way to make new friends and to obtain the most assistance, but speaking to growers at society orchid shows held throughout the country, or even just obtaining the name of a grower who may be able to assist over the phone may be all that you require. Orchid growers are renowned for their enthusiasm for speaking about their favorite plants, so never be afraid to seek advice or assistance.

Most of the paphiopedilums grown have been developed from plants native of the Asian lowlands, although some grow naturally at higher altitudes in the Himalayas. The various species come from a considerable range of habitats, from the high mountains to sea level. Thus there is a range of both cool and warm growing plants to select from. Fortunately, by just looking at most of the plants you can gain an indication of their temperature requirements, although there are always exceptions, and for some of the advanced hybrids the distinctions are not so clear.

While there are some that are epiphytes, i.e. they grow on the branches of trees, although unlike parasites, do not obtain nourishment direct form the host tree, most grow on the ground as terrestrials, in a thick mat of humus, moss and leaf detritus. There are a few that are lithophytes, plants which grow on rocks. Most of their habitats are naturally subject to quite high levels of humidity all year. Of importance to their culture is that their roots are exposed to the atmosphere; they require plenty of moisture, but their growing environment must not retain excessive water. For this reason the use of normal garden soil will be disastrous, and they require a bark or peat growing media. Paphiopedilums lack pseudobulbs, the normal water storage structures found in most orchids. For this reason they require a much more even supply of moisture throughout the whole year.

The growth habit is sympodial, they grow sideways with new growths developed in the spring, which mature over the next 9 to 12 months, produce flowers, and then develop one or two new growths themselves.

Plants can be purchased in flower relatively inexpensively, and this is generally preferable for new growers. Small plants can take 4 to 6 years from seed to reach flowering size. You can grow from seed yourself, but contrary to the usual garden plants, seed must be sown and germinated in sterile containers which new growers can find difficult. Also, the establishment of plants from the flasks, while an interesting challenge, can be difficult for those without some experience of orchid growing or who do not have more than basic growing facilities.

Seedlings can be purchased, which will produce variable flowers even where the same parents are involved, reflecting the variation and quality of the parents. A group of seedlings can be interesting to grow, as you never really know what you are purchasing, and the variation in individual plants gives added interest. Most orchids will, however, be obtained as divisions. Mericlones, which have been a major factor in the improvement in the quality of many orchids, are not available for paphiopedilums, and therefore only divisions of top plants, or seedlings, are available.
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Paphiopedilums in broad terms can be placed into a number of groups based on their cultural requirements.  

GROUP 1     The single flowered green leaved species and hybrids such as Paphiopedilum insigne, Paphiopedilum spicerianum, Paphiopedilum Leeanum are easily grown No supplementary heat is required, although very cold conditions must be avoided. It is plants from this group that are generally recommended for new growers, or for those with limited space or growing facilities.  

GROUP 2     The mottled leaved species and hybrids including Paphiopedilum concolor, Paphiopedilum bellatulum and Paphiopedilum Maudiae. Plants from this group generally have single flowered inflorescences, and require some additional warmth in this country. Often this is more easily provided in the home or small glasshouse by way of a heat board or propagating bed. The mottled leaved Paphiopedilum venustum naturally growing at high altitudes, is an exception, being suited to Group 1 conditions.  

GROUP 3     The green leaved paphiopedilums having multiflowered inflorescences, the individual flowers which open either in succession or together, depending on the plant involved. These generally require more heat than their mottled leaved cousins. These plants are generally larger growing than those found in either Group 1 and 2. 
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 The general growing temperature groupings widely noted for orchids, and those required for the three paphiopedilum groups can be summarised as follows:-

  TEMPERATURE GROUPINGS 

Optimum range targets 

All in degrees Celsius 

Temperature groups WINTER SUMMER
          DAY NIGHT DAY NIGHT
COOL 

GROUP 1 PLANTS
10-15 7-10 15-18 7-15
INTERMEDIATE 

GROUP 2 PLANTS
18-20 12-15 18-25 15-18
GROUP 3  INTERMEDIATE BETWEEN INTERMEDIATE AND WARM
WARM 20-25 18-20 20-25 18-20
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 Temperature Conversions
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C U L T U  R E       B A S I C S  

Before anyone commences growing any plants, it is important to remember that successful growing requires - 

  • suitable temperature levels
  • an adequate supply of water  
  • plenty of fresh moving air 
  • suitable light levels    and 
  • a suitable level of essential plant food  

    If you are experiencing growing difficulties it is well worth remembering the above requirements and looking at your culture on this basis. The specific cultural recommendations will be written with the above in mind, and should provide the answers to the main requirements. Observation of your plants and their growing conditions is always the precursor to success. 

    Remember that it is not what you do well that controls your growing success. Rather it is that which you do worst. If, for example, you do everything else right, but forget to water the plants correctly, then the plants will only grow to the extent allowed by the limited water supplied. If you then correctly water the plant, growth will then be limited by the next factor not supplied to the optimum level required.

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SEASONAL CULTURE

SPRING

  • This is the time of the year that you will be starting to enjoy the fruits of your years growing, plenty of flowers. If you are missing a great display, now is the time to review your culture over the past 12 months, and, if necessary, to seek advice.
  • The natural starting point is the time of commencement of new spring growth, especially the start of new root growth. Paphiopedilums have very thick horizontally spreading roots borne from the base of the plant. They are relatively brittle, so handle with care as they can be easily damaged, especially during repotting. Growth will commence earlier in the north than the south, so you will need to observe your plants closely.
  • Flowers can be left on the plants without harm as long as the plant is healthy. They can also be removed and enjoyed as cut flowers for just as long. With small plants flowering for the first time, the quick removal of the flowers facilitating maximum vegetative growth ensures strong subsequent flowering in future years.

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  • With the removal of the flowers and new growth commencing, now is the time for repotting.
  • Repotting, the replacement of the growing material, is required when  -
    • - the plant has grown too large for the existing container, or
    • - the existing potting material has broken down and must be replaced.
  • Most plants require repotting every second or third year as the potting material gradually breaks down thought normal bacterial and fungal decomposition. Small plants will respond with increased growth if they receive more frequent repotting, say every six to nine months if some supplementary heat can be provided, otherwise every 12 months.
  • Many other garden plants can be potted on i.e. placed in a larger container when they have outgrown their existing one, with new potting mix added just to fill the new larger container. With orchids this 'potting on' is not generally recommended. It is preferable to replace all the potting mix to give the plant a completely fresh start.
  • Paphiopedilums are repotted in a variety of growing mixtures, which are generally bark based. A good mix must be free draining but at the same time retain moisture. For most of New Zealand bark based mixes will be the best, most readily available and least expensive alternative. The watering habits of the grower can influence mix selection. If you are a compulsive user of the watering hose, then you will require a more open free draining mix. On the other hand, someone who neglects watering, or is away from home for periods, may prefer a finer mix, one able to retain water longer. The size of the container is also relevant, as smaller pots tend to dry out quicker that larger ones. When selecting a suitable potting mix consider the conditions over the whole year, not just a particular season. If summers are hot and dry, you may think a moisture retentive mix may be best, but if the winters are really cold, the wet mix under cold conditions will often lead to root death and in such situations you may be better to utilise an open mix but have to water more frequently during the summer. This is a typical example of fine tuning requirements to a particular locality.
  • Commercial mixes are available, although you can make your own if you know what you are doing. Commercial mixes also usually have fertilisers added which will last 6 to 9 months, and so can be more convenient.

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  • Generally bark based mixes will be most successful, although there are many varied opinions as to what is the best. In addition to chopped bark, other material can be added, such as scoria, pumice, plastic foam chips, aquarius (florists) foam, horticultural charcoal, and /or sphagnum moss (New Zealand of course)  as a matter of personal choice. The final choice of mix suitable for a particular locality will come though experimentation and experience. A good basic mix to commence with is as follows:-
    • Graded pine bark - 5 to 25 mm pieces 10 liters
    • Garden lime 100 ml
    • Dolomite lime 100 ml
    • Soluble nitrogenous fertiliser (e.g. Lush or similar) 10 ml
  • The above mix is suitable for large adult plants. For smaller plants reduce the size of the largest pieces. In all cases the dust and fine granules must be removed
  • Sphagnum moss, often added to bark mixes, has also been successfully used on its own by some growers, either as long strands or chopped, but care must be exercised with this material. It can break down very rapidly, especially if a high fertilising regimes are followed, and quite different watering requirements will be necessary as compared with bark mixes. Shredded tree fern fibre is also popular in some areas. Varying products behave differently, so once you have made a choice, use that product for the whole collection. If you wish to experiment, do so with a few spare plants first to see how the new material performs over a year under your conditions before changing over the whole collection.
  • Plastic or clay containers can be used. Most will find plastic pots are preferable and least expensive. In selecting the size of the container, remember it is the size of the roots that dictate the size of the container, not the amount of top vegetative hamper. Also, ensure the container has plenty of drainage holes. For some pots you may have to add additional drainage, by drilling, or preferably, by burning with a hot iron or similar.
  • Repotting is not a difficult exercise, although it one that troubles some growers. If you are worried, then discuss with an experienced grower from a local society. Someone will probably even be prepared to help you the first time. At some orchid shows, experienced growers often run repotting demonstrations, which can be a great place to learn the basics of this process.
  • Once you have selected a mixture, some days before you want to use it prepare it by soaking the bark in water for three of four days. As the material tends to float, stir vigorously two or three times a day. The day before you want to use it, drain the water away by tipping on concrete, or hanging up in a hessian bag so that it is moist but not wet. If the mix it still very wet while you are repotting, difficulty can be experienced in getting the mix to flow around and through the roots

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  • Remove the plant from the existing container, and carefully extract all the existing growing mix with your fingers or a jet of water. Remove any dead roots. If required break the plant into pieces if it has grown too large. Allow the broken surface of the rhizome to be exposed to the air for an hour or so to callus over, or treat with a fungicide or even just flowers of sulphur, which can be easily applied in a puffer pack. It may be desirable to even trim the roots, and this will not harm the plant and they will quickly regrow provided repotting is undertaken just as the new growth commences in the spring. Place in the pot with the base of the plant some 25 mm below the rim of the container, and work the mix in and around the roots. Bumping the container on a bench can also assist in the placement of the mix.
  • Plants must be firm in the mix, but not too tight. You should be able to lift the plant in the pot by its foliage and not cause it to fall out of the container 9 times out of 10. If most do, place the potting mix more firmly; if none do, do not place the mix so tightly.
  • If the division lacks roots you may have to stake the plant in the container. If it flops around the new developing roots can be easily destroyed, so you need to be able to stop this occurring.. Place the stake near the rhizome, preferably as repotting is being done so you can see where the roots lie and ensure they are not damaged. Often a tie around the base of the leaves to a short stake is all that will be necessary to secure the plant satisfactorily. If you have to stake an already established plant to support a flower or for any other reason, avoid the outside of the container, as many roots circle the inside of the container. Placing labels against the inside of the pot can also damage roots.
  • Small growths which are removed or accidentally broken off, or divisions without growing roots, can be wrapped in damp sphagnum moss in a closed plastic bag, placed in a warm shaded position. Over the next few weeks roots will develop, and once these reach 25 mm or so long, the plant can them be removed and potted up in the normal manner.
  • After repotting is completed, keep the plant in a warm shaded position and keep on the dry side for 2 to 3 weeks. It is desirable to mist the foliage regularly as paphiopedilums lack the usual orchid water storage organs, the pseudobulbs. Once normal growth re-commences, it can be returned to the normal watering regime followed for the rest of the collection. The aim is to get as strong and vigorous growth as quickly as possible which allows the plant to reach maturity earlier to ensure maximum flowering the following year.

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  • Repotting is usually only done in the spring ideally just as the new root growth commences, before the new roots grow too long and which may be damaged during the repotting process. You can complete in early autumn but the plants then do not have the same time to re-establish before the winter. Only repot at other times of the year in emergencies.
  • When you purchase new plants, it is often desirable to repot them into new fresh mix as this makes for easier watering. Plants in a variety of growing media can make watering difficult as different mixes dry out at different rates. Repotting also gives you the opportunity to check out the health of the plant generally, but especially the critical root system.
  • During repotting you may divide the plant if it has grown into a large multi growth specimen. Remember, however, that a large plant bearing many flowers can be spectacular, and a real eye catcher when shown in the home or at shows. With large plants, it is the maintenance of its health and vigour in its centre that is the real challenge.
  • When you divide a plant, remember that a flowering division consists of three to four green growths. A plant this size should flower next year, smaller divisions may take several years to produce flowers again.
  • Remember to re-label all plants and divisions. A plant without a label and name looses much of its value. While a species plant can be re-identified, with thousands of man made hybrids their identification from just a flower is usually impossible. The plant label should include the date of repotting.. Labels can be marked with a good permanent marker pen, although a HB pencil will often be the most long lasting. Remember to check the labels periodically as they can fade over time. In addition to the visible label, it can be beneficial to include another buried in the potting mix as insurance in case the other is moved or lost.
  • Always try to have plants with strong healthy root systems, as these will perform best. When purchasing plants one of the main criteria is that they have strong healthy roots, as such plants will re-establish in their new homes so much quicker and earlier and easier.

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  • With warmer conditions gradually becoming the norm during the spring, pay increasing attention to watering. Allow the top of the mix to dry out somewhat before watering. When you do water, apply plenty, ensuring there is a free flow out of the drainage holes at the bottom of the container. Water the plants once, then do it again a few minutes later. Bark mixes in particular can be difficult to wet once they become dry and a double application ensures they hold maximum moisture. Over watering is watering too frequently, not a reference to the amount applied at any one time. How often watering is required depends on the conditions where the plant is growing, the temperature, and the nature of the potting mix - coarser mixes dry out faster then finer ones. Old growing mixes also tend to hold moisture more. In early spring, for large plants, once every 10 days or so may be frequent enough. Smaller plants, and under warmer conditions, more frequent applications will of course be required - say once every 5 to 7 days. The periods between watering will, of course, shorten as warmer summer days approach.
  • As the sun becomes stronger towards the summer, increased shading may be required. Generally the plants will appreciate 30% shading, increasing in bright locations and towards mid summer to 50% shade. The amount of shading can be indicated by passing your hand over the plants on a bright sunny day. The shadow cast should be only faint. Ideally the Group 1 plants should show yellow green foliage, as dark green leaves generally indicate that conditions are too shaded. The leaves should be of good texture, thin long leaves are also indicative of a lack of light. The mottled leaved types lack the contract between the light and dark coloration in bright conditions, with the differences emphasised under shade.
  • Bright light will generally produce the best flowering, but if too bright, unsightly burning of the foliage can occur. It is not the light in itself that is the problem, it is the higher temperatures that occur under bright conditions. If you are growing under bright conditions, increase the air flow through good ventilation or the use of a fan, and, if possible, raise humidity by under bench spraying or misting.
  • Plants growing strongly will benefit from the application of fertiliser. A top dressing of solid fertiliser, or even one of the slow release products, can be suitable, and foliar feeding is also appropriate. Once growths have matured, reduce the nitrogen and increase potash levels in the fertiliser. Either liquid or dry products can be used, applied at around half the manufactures recommended rate. A little fertiliser often is best, as they can resent too much fertiliser. A top dressing of solid fertiliser can be used during the main vegetative growth phase. An annual application in the spring, with lime or dolomite to sweeten the mixture following the winter, can also be very beneficial. At this time of the year a high nitrogen fertiliser will generally encourage strong growths.
  • Paphiopedilums, because of the size of the plants and the flowers, make ideal house plants and table decorations. Because they generally grow in relatively small pots, you can place the growing pot in a more attractive outer container while on display. Remember to keep the plant watered while inside, and where possible under dry conditions, try and maintain humidity as high as possible.

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SUMMER
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  • The growing season will now be well under way. Root action will be strong and the new growths should be developing strongly.
  • Plants can be kept under 30% to 50% shade Maximum shading is necessary during mid summer.
  • Do not crowd them too much in the growing area as plenty of fresh moving air is essential. The green leaved Paphiopedilum insigne, for example, can be grown outside with cymbidiums, but you must remember that paphiopedilums require more frequent watering as they do not have the water storage pseudobulbs of cymbidiums and most other orchids. Placing them on benches or bricks etc. prevents the entry of earthworms and other undesirable insects. entering the pot. Benched plants in a glasshouse need good ventilation, but humidity must also be maintained.
  • Increased watering will be necessary. As this is the main growing period, do not stint this work as you do not want to give the plants any check to their active growth. If you are going away on holiday try and get someone to water the plants, but make sure they understand what is required, as if they are not used to orchids they could cause damage, even loss of plants. In the glasshouse, the use of misting sprays over and under the benches can be beneficial by increasing the humidity levels. Paphiopedilums generally naturally grow in situations where humidity is high for most of the year.
  • ·If plants are grown inside, they appreciate higher levels of humidity. This can be easily provided by using a tray containing a layer of fine gravel. Filled with water to the surface of the gravel, with the plant on top, there will be increased humidity as the water evaporates from the tray. Ensure the plant container can still drain freely, and that the water reservoir is kept full, especially during warm weather.
  • Pests and diseases are generally not a problem. If problems do arise, look at your culture, as many problems can be controlled just through a change in your cultural practice. If you do have a continuing problem, approach your local garden center for specific advice on products and how they should be most effectively applied. Remember all sprays are poisons and must be used with care.
  • Around mid summer, reduce the application of nitrogen fertiliser and increase the application of potash.

AUTUMN
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  • With the development of cooler autumn conditions, any summer shading can be gradually removed.
  • As conditions cool, reduced watering will also be appropriate. Avoid overhead watering, especially if cooler conditions are anticipated, as water lodging in the growths can lead to their rotting. Generally it is desirable to always water early in the day to ensure the plants dry before nightfall, especially in the autumn.
  • Continued fertiliser applications are appropriate, but adjust the amount of application to the amount of growth taking place.
  • With more flowers appearing, continue staking plants, using cane or wire stakes. If you are using wire, turn the tops over and watch your eyes don't get poked out when working with the plants. Small bamboo stakes or even meat skewers can be suitable for paphiopedilums.
  • When moving plants, ensure they are returned to the same orientation to the light source. Turning a plant can cause the flowers to become twisted, spoiling an otherwise attractive presentation. If there are several flowers on the plant, try and get them all to face the same way, producing a m ore pleasing overall presentation.
  • If you are growing without heat under cool conditions, tend to keep the plants dryer than usual, as wet cold conditions are often fatal to roots.
  • Minimum temperature requirements for the various plant groups noted previously should be followed. Mature plants can be grown cooler, but growth will be reduced. The growth of small plants will be facilitated if temperatures some 5oC. higher than is indicated for adult plants is maintained, ensuring the period to flowering is reduced to as short as possible. Ensuring minimum temperatures are met will result in overall better growth and flowering. If heating is required, ensure all systems are 'go' before the winter, as you do not want to be caught out when a sudden cold spell occurs. Remember that once supplementary heating comes on, the atmosphere can dry out quite quickly, and careful extra misting of the plants may be required.
  • Avoid giving the plants a check in their growth for any reason, as once this occurs it can take quite some time for optimum growth to be re-established.
  • If you are growing without heat under cooler conditions, tend to keep the plants drier than usual, as wet and cold temperatures are fatal to roots.
  • Small plants in particular appreciate some additional warmth, and the use of bottom heat provided by a heat board or warming bed can be most beneficial and economical way of ensuring their maximum growth to reaching flowering size as quickly as possible.

WINTER
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  • Adjust the amount and frequency of watering to the amount of plant growth taking place. During warmer days, watering can be more frequent.
  • Fertiliser use can also be adjusted to the amount of growth - during periods of slow growth such as during the winter, reduce applications.
  • Spotting and insect damage can affect flowers. With lower evening temperatures, humidity will increase, especially after a warm day. Good ventilation and air movement is essential.. The use of fans, especially in a glasshouse, is beneficial. Water on flowers can cause spotting, and therefore overhead watering at this time of the year is not recommended. Slugs and snails can also cause damage, and may need to be controlled.
  • Now is the time to enjoy your growing success. Taking some time will ensure your growing efforts are presented to their best
    • - ensure the pot is clean, with all dirt moss removed
    • - remove any dead leaves and old leaf bases from the pseudobulbs
    • - clean the foliage of any old spray residue, dirt, dust etc. Remember when wiping down the foliage, hold the leaves by their bases and wipe from the base to the tip. The leaves, especially from the newer growths, can be easily pulled off if care is not exercised.
    • ensure the plant is correctly labeled, especially if you are going to present it at a show.
  • The plant has expended considerable energy in producing the flowers. The best results will only be obtained if the plants are healthy and in good condition. If there is any doubt regarding the vitality of the plant, the flowers should be removed quickly. Most paphiopedilums are long lasting as cut flowers, so you can enjoy the flowers for several weeks, and in some cases, months. The flowers last nearly as long as cut flower as compared with leaving them on the plant.

 

Remember

  growing orchids is all about  enjoying your plants and  sharing your growing success with friends and neighbours.

  Good luck and good growing. 

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Remember,
growing orchids is all about enjoying your plants
and sharing your growing success with friends and family.

Good luck and good growing.


 
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Site established 9th May 1998
Paphiopedilum series first uploaded 8th December 1999