ORCHIDS are for EVERYONE

CYMBIDIUMS
Seasonal culture
  

Philip C. Tomlinson  Capital City Orchid Society   © 1997 

May be reprinted for non commercial purposes  with full acknowledgemen

WELCOME TO THE WONDERFUL WORLD OF ORCHIDS
REMEMBER -
ORCHIDS ARE FOR EVERYONE

 

INTRODUCTION

Cymbidiums are perhaps the most popular of all the orchids grown in this country, and the one most people commence their orchid growing career with. Now widely available, not only from the specialist orchid nurseries, but also from the such as local garden centres and supermarkets, they will provide years of pleasure and a great display of flowers provided their basic cultural requirements are supplied. Amongst the uninitiated orchids are commonly thought to be delicate plants requiring expensive growing facilities. Cymbidiums are, however, strong robust plants capable of surviving quite extreme conditions, although, of course, their growth and flowering will be much better and more assured when their relatively simple basic requirements are provided. In most parts of the country an open porch or a convenient shady tree will suit them for most of the year; they only need protection from the worst weather and from the rain and cold during the winter months, a period when many of them will be displaying their magnificent flowers in any case. Then they can be brought inside, and the flowers enjoyed on the plants for weeks, and indeed in some cases, even for several months.

Cymbidiums will be grown in all parts of the country, from the far north to Stewart Island in the deep south. 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 local growing advice. In particular the members of local orchid societies will be happy to assist with local information. Joining a society in your area is the ideal way to make new friends and to obtain the most assistance, but speaking to growers at the local society orchid shows held throughout the country, or even just obtaining the name of a local 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 assistance.

Most of the cymbidiums grown have been developed from plants native of the Himalayas, from quite high altitudes, although some of the smaller forms now found incorporate species from Asia, some of which do require warmer growing conditions. Most are epiphytes, i.e. they grow on the branches of trees, although unlike parasites, do not obtain nourishment direct form the host tree. Some, especially the Asian species, grow in leaf detritus on the ground. Of importance to their culture is the fact 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 the use of specialist bark and peat growing media is required.

The plants are natives of areas which are exposed to the summer monsoons, where the summers are warm and wet and relatively dull. Winters on the other hand are cool, bright and relatively dry. This is contrary to the normal conditions experienced in this country, with warm dry bright summers, and cool wet and relatively dull winters. For success the particular requirements of the plants must be met. It is important, also, that the summer temperatures at night are cool, to allow for maximum flower bud initiation. Inside a closed porch or glasshouse over the summer is generally not conducive to maximum flower production; keeping plants outside under dappled open shade with plenty of fresh moving air is the ideal. Growing the plants with too high summer night temperature is one of the most common reasons for non flowering.

There are cymbidiums ranging in size from small flax bushes to diminutive pot plants able to be used for table decoration. The larger standard cymbidiums, while putting on a great display, can be too large for bringing inside, but the so called 'miniature' cymbidiums are ideal for house decoration. Cymbidium flowers are long lasting even when removed from the plant, so flowers from even the largest plant can still be enjoyed in the home. There is a well developed industry producing cut flowers for export and the local market, but expert advice is required for those considering entering into commercial production. .

Plants can be purchased in flower relatively inexpensively, and this is generally preferable for new growers. Small plants can take 4 to 5 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 experience of orchid growing or lacking anything 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 an added interest. Most orchids will, however, be obtained as mericlones. These are laboratory produced copies of the original plant. These allow selected and perhaps award winning seedlings to be propagated in large numbers for wider enjoyment. If you see the original plant of the mericlone you will know that all its mericlones will be the same. Mericlones have been a major factor in the improvement in plant quality, as the process allows the very best of all plants to be made available at reasonable cost. In many cases divisions of larger plants are available, as are back bulb propagations.

CULTURE BASICS 

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.

SEASONAL CULTURE

SPRING

  • This is the time of the year that you will be enjoying 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. This is apparent when the roots show bright green growing tips to the normally thick, white healthy roots. This growth will commence earlier in the north than the south, so you will need to observe your plants.
  • Flowering spikes can be left on the plants without harm but can be removed and enjoyed as cut flowers for just as long. When ready, break the spikes, do not cut them off as the serious virus disease can be transferred by the cutting instrument from one plant to another. Do not bring flowering plants into a warmer home too quickly, and the higher temperatures can cause the unopened buds to abort. Ideally all the flowers should be open before they are brought inside.
  • 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 material gradually breaks down though normal bacterial and fungal decomposition. Small plants will respond with increased growth with more frequent repotting.
  • 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 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 it a fresh start.
  • Cymbidiums are repotted in a variety of growing mixtures, which are generally bark or peat 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. However, for the warmer northern localities a more moisture retentive peat mixture may be better. Southern areas, with their colder winters, will generally experience difficulties with peat mixes as these tend to keep the roots too wet during the cooler winter, often leading to root loss under cold conditions. The watering habits of the grower can also 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 of the year, not just a particular season. If summers are hot and dry, you may think a moisture retentive peat 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.
  • Plastic or clay containers can be used, even plastic growing bags. Most will find plastic posts 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 hamper.
  • 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, before you want to use it prepare it by soaking in water for three of four days.. The day before you want to use it, drain the water away so that it is moist but not wet.
  • Remove the plant from the existing container, and carefully remove 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. It is preferable not to cut the rhizome between the pseudobulbs as the serious virus disease can be spread by the cutting tool. Allow the broken surface 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 the plant in the container with the rhizome 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 its placement.

  • 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.
  • Big plants can be difficult to handle and display, but large specimens can be spectacular. When you divide a plant, remember that a flowering division consists of three to four green pseudobulbs which should flower again next year. Smaller divisions can take several years to recommence flowering
  • 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, 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.
  • 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 if any shriveling of the pseudobulbs is noticed. This will allow the quickest re-establishment and once new growth is apparent, resume normal culture. The aim is to get as strong and vigorous growth as possible which reaches maturity as quickly as possible to ensure maximum flowering the following year.
  • Repotting is usually only done in the spring. 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 a 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 root system.
  • During repotting you may remove a number of back bulbs - old leafless pseudobulbs - from the plant. Do not throw these away. Potted up in a small container, many can be encouraged to grow again, and in 4 or 5 years you will have another flowering plant. You can also place them in a closed plastic bag with some damp sphagnum moss in a warm shaded position where they can remain until roots have grown 25 mm long, at which stage they are then potted up. Growing back bulbs make ideal gifts to non orchid growing friends; I have encouraged many peoples interest in orchid growing through the gift of back bulbs and divisions.
  • Remember to re-label all plants, divisions and back bulbs. 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 looking at the 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 the 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.

  • 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 row 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. As conditions warm up towards the summer, more frequent watering will obviously be necessary.
  • As the sun becomes stronger towards the summer, increased shading may be required. Ideally the plants should show yellow green foliage, dark green leaves generally indicate that conditions are too shaded.
  • Plants growing strongly need to be fertilised as cymbidiums are gross feeders. A top dressing of solid fertiliser, or even one of the slow release products can be suitable, and foliar feeding is also suitable. Generally apply fertiliser at some half to a third of general garden recommendations. - a little often is generally the best policy. At this time of the year a high nitrogen fertiliser will generally encourage strong growths.
  • The developing new vegetative growths must be handled with care. The foliage is quite soft, and the young leaves at the center of the growth can be pulled away quite easily, if, for example, you lift the plant by the foliage.

SUMMER

  • The growing season will now be well under way. Root action will be strong and the new growths should be developing strongly.
  • With temperatures now increasing towards their maximum, the plants should be in their summer homes. Do not leave plants in a closed porch or glasshouse as they need plenty of fresh moving air. Summer night temperatures of not more than 10-12 oC are essential for the completion of flower bud initiation. This is enhanced by higher light levels.
  • Plants can be kept under 30% shade, or under the open branches of a tree will also suffice.
  • Raise the plants off the ground, and do not crowd them too much as plenty of fresh moving air is essential. Placing them on benches or bricks etc. also prevents earthworms and other insects. entering the pot.
  • 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.
  • Watch for red spider and false spider mites on the plants, as these pests can become established very quickly especially under the hot dry conditions often experienced at this time of the year. The pests themselves can be difficult to see, but their effects can be easily identified by silvery markings to the undersides of the leaves. The frequent misting of the plants, under the foliage will discourage them, although if they become established the use of sprays may be necessary. Approach your local garden centre 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. While actively growing, cymbidiums are gross feeders, and they respond to frequent feeding. Do not feed sick plants, however, as this can accelerate their demise.
  • The application of Epsom salts (magnesium sulphate) at the rate of 1 teaspoon per 5 litters of water, watered in, will facilitate spike initiation.
  • Next seasons flower spikes will be appearing now. To make sure they are not damaged, ensure they are all securely staked, and that they are retied as they elongate.. With stakes rising through the foliage, take care handling the plants that you do not injure yourself.
  • The flower spikes come from the base of the pseudobulbs, the flower spikes being more rounded that the new vegetative growths.
  • Do not insert the stakes around the rim of the container as there will always be a concentration of roots there, and you want to avoid damaging them. There are varying spike habits, depending on the plant - upright, arching to sharply pendulous. It is always preferable to allow for the natural growth to develop, and the placement of the spikes must allow for this. Be careful with the developing spikes as they can be easily damaged and destroyed if care is not exercised.

AUTUMN

  • With the development of cooler autumn conditions, any summer shading can be gradually removed.
  • With cooler weather, bring plants into more protected positions, especially those showing flower spikes.
  • As conditions cool, reduced watering will also be appropriate. If there are tube growths present, 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 water early in the day to ensure the plants dry before nightfall.
  • 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.
  • Bring the plants into the house to enjoy once all the flowers on the spike have opened, which can take a week or so. Bringing a plant inside which still has flowers in the bud stage can cause these to be aborted and lost, especially if the home is kept comparatively hot.
  • When moving plants, ensure they are returned to the same orientation to the light source. Turning a plant can cause the spikes to become twisted, spoiling an otherwise attractive presentation.
  • There is a close relationship between the amount of light and the final colour of the plants. Different plants react differently, but generally the stronger red, brown and darker pinks and brighter yellows require stronger light for the best colour to be produced. Whites, green and pastel colours, however, should be shaded, green flowers in particular should be heavily shaded for best results. Once flowers are open, then shade to stop fading of the colours.
  • All plants appreciate temperatures over 10oC. Mature plants can be grown cooler, but growth will be reduced. While cymbidiums can be grown without any supplementary heat in most locations, some heat under cooler conditions will result in better growth and flowering. Temperatures maintained over 15oC during the autumn and winter, especially for small plants, is ideal, but in many locations will only be obtainable at a cost which is not acceptable to the grower. 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.
  • 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 and back bulb propagations 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

  • Adjust the amount and frequency of fertiliser to the amount of plant growth taking place.  An inactive plant is not capable of using fertiliser, and when growth is reduced, reduced applications are appropriate.
  • Watering will also be adjusted to the conditions,  -  with cooler conditions the frequency of watering will be reduced.  If cold conditions are expected, then the plants should be grown dryer than usual.  Plants that are waterloged may loose their roots under cold conditions.
  • 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 spike and 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. It is generally recommended that spikes should be removed 2 to 3 weeks after the last flower on the spike has opened. At it takes 2 to 3 weeks for all flowers to open, there is quite a long period for he flowers to be enjoyed 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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