Cultural Notes. Native Dendrobium and Sarcochilus. (den-dro-bee-um and sar-ko-kye-lus)

Transcription

1 Cultural Notes Please remember that guidelines provided in these Culture Notes are very general, conditions will vary from home to home and greenhouse to greenhouse even within the same town. Your own observations are an essential part of proper culture. If you would like more information, talk to one of the club members growing the genus of orchid that you need assistance with, they may be able to give you more tips, but please keep in mind specific advice is hard to give. Native Dendrobium and Sarcochilus (den-dro-bee-um and sar-ko-kye-lus) January This is the middle of the growing period for these orchids (although Sarcochilus tend to slow down a little in the heat) and they should be fertilised and watered regularly. I only ever use a low Nitrogen fertiliser on my Natives. I find this encourages good roots and makes for strong, healthy growth which is very resistant to pests and diseases. When watering, make sure the plants are thoroughly soaked and then allow them to almost dry out before watering again. Both Dendrobium and Sarcochilus hate soggy mix. Watch out for pests such as scale, aphids, caterpillars etc. and diseases like fungus or bacteria and treat the affected plants appropriately. Please take care with chemicals whenever using them. Sarcochilus will appreciate extra shade at this time of year. I add an extra layer of shade cloth over them in November and find they benefit from it. February Our plants should still be growing strongly with new canes (pseudo bulbs) extending. The aim is to have these mature by Autumn so they will add their flowers to what should be a fine display. This month is generally our hottest and watering should be watched closely. I find an additional light watering in the evening in addition to my normal morning soak will help to keep the plants growing well; but do wait until the sun is off them or you could do more harm than good. Keeping air moving over our orchids does far more to combat heat stress than excessive watering. If you have not already done so, increase shade for the Sarcochilus, even to the extent of moving them to a more comfortable area. Keep fertilising regularly and remember to keep the mixture weak; never more than half the recommended strength. Little and regularly are the watch words! March Now the growing period is ending and the maturing time beginning. Continue with watering and fertilising but gradually reduce the amount of water used so that the plants have a definite drying out period of a couple of days. The end of this month I find is a good time to re-pot Sarcochilus. They seem to have a new burst of growth about now. The Tropical and Hot/Cold Dendrobium hybrids will often show signs of spiking about now, although the Hot/Cold hybrids can flower just about any time from now to November! It all depends on their parentage. April Native Dendrobium should now be maturing and preparing to flower. Watering should be reduced but fertilising (with a low N fertiliser) should continue. Remember never fertilise a dry plant the day before. I try to fertilise when the mix is almost due for watering. To fertilise a plant in wet mix is a waste of time and money as the velamen (the specialised cells covering the roots) will not absorb the fertiliser if they are already saturated. Water heavily a couple of days after fertilising to flush out any excess salts. I move my Tropical natives such as Den. bigibbum and Den. canaliculatum into a sheltered area where I can maintain a minimum temperature of at least 10 degrees Celsius and increase the light for them if possible. At the same time the extra shade over the Sarcochilus may be removed. May We can expect some of the Tropical natives such as Den. bigibbum to start flowering. Others such as Den. canaliculatum, triamellatum etc. don t normally flower until Spring. I find the secret with the Hot/Cold hybrid Dens. is to keep them quite dry from next month until Spring. Just an occasional light watering to prevent the canes shrivelling too much is all that is required. The very small Hot/Colds I keep together with my Tropical natives and find that they benefit from this. When they reach 120 mm pot size they can generally be left to their own devices, but try to keep them as dry as possible, they will flower better this way. As buds form on the cool growing Natives (most of them), move them under cover to protect them as much as possible.

2 Native Dendrobium and Sarcochilus Culture Notes - continued June The early flowering Dendrobium should now be starting to open. Native Dendrobium and Sarcochilus now enter a semi-dormant phase and water should only be given very sparingly. I see no point in wasting money fertilising them at this time of year. The warm growers are now spiking and starting to flower. Reduce water for these plants and give them as much light as possible. This is quite a busy time of year with Shows taking place all over Perth and it is a good idea to see what is flowering with a view to increasing the range of our collections. The first flowering seedlings are usually very exciting! July This is the resting time for the cool growing Native Dendrobium. Flower spikes should be extending, with some already showing their beauty with open flowers. Try to move those in bud under cover before the flowers open to minimise weather damage. The plants will benefit by being kept rather dry. Don t let the mix dry out completely though; it then becomes very difficult to wet it again. The warm growers (Tropical and Hot/Cold hybrids are now flowering and watering should be almost finished. This is a good time to prepare potting mix and ensuring you have enough clean pots for re-potting. I keep my potting mix (pine bark and some stone such as blue metal or cracked gravel) in 50 litre dustbins. Make sure it is nice and moist not wet and there will be no panic when the time comes to re-pot or pot on. August This is the resting time for the tropicals. It is important that they get no water and certainly no fertiliser at this stage. If the pseudo bulbs shrivel slightly this is all to the good. If this appears a little excessive then a light misting is all that is required. The cool growers should now be in full flower with new plants opening every week if you don t see this then you haven t got enough of these wonderful orchids! Resume watering gradually, remembering not to overdo it, and you can start lightly fertilising. Start re-potting as the flowers finish. I like to change my potting mix every 3 to 4 years even if the plants don t really need a bigger pot. Don t divide Native Dendrobium unless absolutely necessary as a big plant is much more spectacular than a small one. September Sit back and enjoy the fruits of your labours! This is when flowering is at its best. Don t sit for too long though, as growth is restarting and watering and fertilising need to be increased gradually. Don t overdo either yet though. Try to have the majority of re-potting finished by the end of the month there will always be some late flowering plants to upset these plans though. The warm growers should still in flower and watering can re-commence by the end of the month. Not too much though the monsoon hasn t yet started light, infrequent showers are the idea. Spring catalogues should now be available to whet the appetite for new plants. October Continue re-potting as necessary. Although the early Sarcochilus have already started flowering, this is the main flowering period for this genus. As the Dendrobium diminish so the Sarcochilus take over and continue into next month. As the weather warms, so these plants will need more water. Don t overdo it though; they still need to dry out (nearly) between waterings. The Dendrobium are starting their growth cycle and watering and fertilising should be a matter of routine now. Don t overlook any mounted plants these still need watering and fertilising. In fact, as they dry out so quickly, daily attention is probably required. The warm growers are now starting their new growth also and thought should be given to making sure they have plenty of moving air as well as water and feed. It is probably still too early to submit them to an uncontrolled environment as nights can be quite chilly. November Sarcochilus that have finished flowering can be re-potted as necessary this month. As the weather warms up, shade should be increased over covered areas (by covered areas I mean areas with fibreglass or other waterproof roofs) as the heat can still take us by surprise and cause damage if we are not prepared. All plants should now be growing strongly and watering and fertilising need close attention. Don t forget any mounted plants, and make sure pots are allowed to dry somewhat before re-soaking. Towards the end of the month we should think about increasing shade over the Sarcochilus. December Re-potting of Sarcochilus can still be done this month unless we have a very hot spell. Both Dendrobium and Sarcochilus should be growing strongly now and attention to watering and fertilising is most important. Watch out for pests and diseases and treat them individually as necessary. I find slaters in my Sarcochilus are a real bother at times and Richgro Slater Killer seems to help minimise their damage. During very hot spells I find it helps to cool down my orchids by giving them a light spraying in the evening once the sun is off the plants. Frank Vernon

3 Cattleya (KAT-lee-ya) Light Cattleya require good light with about 70% - 80% shading in Perth's summer and can be grown with Cymbidiums in shade cloth conditions quite happily. Shading can be provided by fibreglass sheeting, but not clear glass or sheeting, as this may allow direct sun onto the plant resulting in a severe case of sunburn and a short life expectancy. A good guide to correct light is olive green foliage, NOT lush dark green foliage, and bulbs should develop straight and upright without the need for staking. Temperature Cattleya can be grown cold and will flower well. Ideal temperature conditions are in the range degrees Celsius. Frost must be avoided under any circumstances also severe summer temperatures. The glasshouse provides good winter protection to the plants from rain and frost, it also enables good winter temperature control, which may allow the plant to flower twice per year without a noticeable winter resting period and young plants will mature quicker. If plants are grown cold, provide them with winter frost and rain protection. Clear fibreglass sheeting can be used in winter as it helps provide full light for the plants. Do not place the plants too close to the glass as they can get; too wet through condensation, too cold or too hot as the glass will transfer the outside conditions to the plant resulting in damage. The glasshouse can be painted in summer to provided shading and sun protection and for winter most of the paint is removed. A lining of clear plastic sheeting inside the shade house can help lift winter temperatures. Ventilation All orchids require fresh air on a regular daily basis; always allow the air to circulate without drafts if possible. Air circulation must include fresh outside air to help clear the various gasses which build-up in a closed house. In winter, half an hour will probably be sufficient to freshen up the air without a serious loss of temperature. Fungal diseases will increase in proportion to the lack of fresh air, along with a failure of plants to thrive. Watering More plants are killed through over watering than any other cause. Cattleya have evolved water storage organs to withstand periodic drying out in their native habitats, they do not like wet feet, however watering regularly in our summer is a must and should be carried out in the morning, and this will allow the roots to dry out during the day. Watering twice a day may be necessary on extremely hot days (35 degree Celsius plus) during mid-summer as the potting medium will dry out very quickly and the plant may come under stress resulting in bulb shrinkage and loss of flowers. SUMMER - at least once a day, less on cloudy days. AUTUMN, SPRING and EARLY SUMMER water about every second or third day. WINTER - provided the plant is kept out of the rain; about every fourth or fifth day. The more open the potting medium (chunky bark), then the chances of over watering are decreased but the chances of under watering may be increased. There is no substitute to giving the plant a good eyeballing and a gentle disturbance of the potting mix to see what is going on inside the pot. If the roots look muddy and not white it is often a sign that the root has been/is too wet and is rotting, if however the root looks green or firm and whitish then the watering is probably sufficient. Fertilising Cattleya obtain nutrients in nature from bird droppings and broken down leaf matter that falls around it. We do not believe in the use of a lot of fertilizers. We add slow release fertilizer to our potting medium at the rate of one tablespoon to a 200 mm pot (8" pot). The slow release fertilizers we use are Nutricote (3-4 month release) and Magamp. The slow release fertilizers are mixed into the pine before potting. Re-potting Large Cattleya plants will still grow and flower well when the new growth has reached the edge of the pot and its roots are outside. For best appearance these plants should be either repotted or divided. It is best to repot or divide in spring. Cattleya should be repotted into new mix at least every two to three years otherwise the root system will start to deteriorate. Small plants will require potting at a more frequent interval until they reach a 150 mm size pot. They are best grown in a plastic squat pot with extra drainage holes cut in the bottom.

4 Cymbidium (sim-bid-ee-um) How to Grow and Flower Them - the Basics Cymbidium orchids are perhaps the easiest of all orchids for the average gardener to contend with. Provided they are given a few basic requirements they will both grow and flower easily. These basic requirements are: excellent drainage; good light and fresh air. To these should be added food and protection from pests and diseases. Let us look at these requirements in a little greater detail. Excellent drainage this is so important I have placed it first. Cymbidiums will not grow in ordinary potting mix they will in fact drown as they, like most orchids, need air around their roots. Constant moisture prevents this and I have found the most satisfactory and easily obtainable medium is pine bark. Most orchid nurseries and some general nurseries sell a suitable mix but I would strongly advise that any medium is put through a sieve (1/4"-3/8" will do) to remove most of the dust before using it. By using pine bark, or something similar such as wood chips, there is little danger of over watering your orchids. It also helps to keep the pots off the ground. Even three or four inches will help and old refrigerator shelves or similar supported on bricks will do quite well. Serious growers usually use weld mesh for benches which is ideal. Never ever use saucers this is one of the quickest ways to kill orchids. Good light is a more difficult subject to quantify. I grow my Cymbidiums in a shade house covered with 50% shade cloth and, for the average garden grower, this is ideal. Insufficient light is the main reason for these orchids failing to flower. On the other hand, too much light will burn the leaves and, as these are the power plants of all vegetation, will also prevent the orchids from forming flower spikes. Generally speaking, deep green, drooping leaves mean too much shade while pale and yellowish leaves means not enough. Morning light is most beneficial so try to position the plants where they get a lot of light up to about am, after this, more shade will help prevent leaf burn. Fresh air is most important. The area between house and fence is NOT the best place to try to grow orchids. This is so often a dark and airless area. Growing Cymbidiums on mesh benches not only aids good drainage but allows air to flow all round the plant. The more air movement you can allow them the better these orchids will grow. Other hints Cymbidiums, although not greedy plants, still need some food. I find that giving them fertiliser once a fortnight is sufficient. My preference is for a liquid fertilizer slow release fertilisers will do as a last resort but with liquid fertilisers I can more easily make sure I give the plants what they need. Whatever you use, please do not give them too much. Half the amount shown on the packet, bottle, or whatever is quite sufficient. Too much tends to burn the roots and, without good roots you will not get good flowering. Any good commercial fertiliser is okay. I find that black plastic pots are most suitable: these are also the cheapest which is an advantage, however they seldom have enough drainage holes and I always increase the drainage by making more holes or enlarging the existing holes. Watering in summer is most important do not over water if in doubt leave watering for another day. The easiest way to find out if the plant needs water is to push a finger into the mix if damp don't water. By using pine bark as a potting medium it is very difficult to over water Cymbidiums as this drains very well Even so, it will break down over time and decrease the drainage. I re-pot every three years into fresh bark even if the plant does not look as if it needs it. Better safe than sorry. Pests and diseases are not a real problem with Cymbidiums. Scale can sometimes occur as can aphids; in these cases the usual garden pesticides will clear the problem. Sometimes these orchids can be affected by wet rot of the bulbs. The remedy is simple cut the affected bulb off as close as possible to the base and apply neat fungicide powder to the cut. Keep the plant a little drier than usual for a week or two and this will often cure the problem. For more detailed information on these subjects I would suggest you contact an experienced grower in your area or join one of the several Orchid Societies. You may also find my book Growing Australian Native Dendrobium in Perth helpful as this covers subjects such as building shade houses, fertilisers, pests and diseases, etc. in some detail. Frank Vernon

5 Phalaenopsis (fail-eh-nop-sis) GROWING PHALAENOPSIS ORCHIDS IN PERTH (a brief guide to get you started) INDOORS To grow your Phalaenopsis (fail-eh-nop-sis) orchid indoors, simply choose a WELL VENTILATED spot away from heaters, as with all indoor plants, and not directly on windowsills where in summer the sun can cause sunburn, and in winter, the glass will conduct cold. To provide some humidity, place your plant pot OVER, not INTO a dish of wet pebbles, stones, blue metal etc to the length of the leaves (placing the pot on an upturned bowl in the pebbles will keep it away from the actual water). Water your plant when the pot feels a little lighter, about everyday in summer and 6/7 days in winter, but this is just a guide, feel inside your pot, it should be moist, not wet, and don't over water in colder weather. As with all indoor plants, ALWAYS WATER IN THE MORNING SO THE PLANT HAS TIME TO DRY OFF DURING THE DAY. If the plant is still wet in the crown (centre) after a couple of hours, dry it out carefully with a tissue or cotton buds, as a wet crown may develop crown rot. During the hot days, MIST the leaves with water several times day (keep your misting bottle handy). This keeps your plant cool. If you have evaporative cooling, your plants will love it, but they don't take too kindly to refrigerated air-conditioning, as it dries out the air. Providing humidity is important. This goes for all indoor plants. Fertilize every week with a balanced product. A good idea is to use a soluble fertilizer and water it in, as directed on the packet. Your Phalaenopsis will look great in a decorative outer pot, but make sure that there are drain holes in it, and lift your plant pot up off the floor of the decorative pot just a little. Making your pebble dish more interesting with small ferns, and other low light complimentary plants will assist all of them to grow happily in a friendly eco environment, and your display will invite pleasant comments from visitors. OUTDOORS It is possible to grow your Phalaenopsis outdoors for several months of the of the year, that's during summer, when the flower spike has been removed, up to May when the next season's spike should be forming. It should then be grown indoors to protect it from the cold weather, unless you have an outside hothouse, with an absolute minimum temperature of 15 degrees Celsius. In summer it is important to provide heavy shade and a cool atmosphere for the plant, so put it in your fern house if you have one, or with your other orchids, down low in the shade house (not on the ground) for maximum shade and cooling. These plants grow in the under story of the tropical rainforest where it is cool and shady. Of course in summer you will need to water it often, early in the day, making sure that the crown has dried, and misting frequently is beneficial just as if you were growing it inside your house. Keep your plant away from hot windof course, and OUT OF DIRECT SUNLIGHT. REPOTTING Repot your Phalaenopsis into fresh orchid bark when the roots are crowding out of the pot. The fresh bark should be without any soil, twigs, leaves or dust etc, so sieving your bark to remove these is a good idea. Use a grade of bark AT LEAST 20 mm to allow easy drainage, and you could add one third charcoal if you wish. MAKE SURE YOUR CLIPPERS ARE WELL STERILISED FIRST, AND DON'T DO MORE THAN ONE PLANT IN BETWEEN STERILISES. After removing the plant, trim the roots and dip them in a weak anti-fungal solution (Listerine, Previcur etc). The new pot should be either the same size, if the plant hasn't grown much, or a larger one if it has. The new bark should come to the junction of the lowest leaf. Water it in well, and then follow the above growing instructions. MISTING RATHER THAN WATERING THE PLANT HEAVILY DURING THE ROOT RE-GROWTH PERIOD WILL HELP KEEP THE LEAVES BUOYANT. As a general rule, more roots and larger leaves mean larger bark and a larger pot, which should have MANY DRAINAGE HOLES so your plant will grow more healthy roots. The lowest leaf of the plant will turn yellow and drop off from time to time, this is normal, but you should have two or more green leaves intact at any time. lf the bulk of the leaves take on a very pale green or yellowish hue, you are probably growing it in too much light, or aren't fertilizing enough, so try another position for your plant, and perhaps fertilize more often. A call to the growers, Greenmasters, on for help with any problems you may have. For people de-flasking, it is beneficial to grow the tiny plants in live sphagnum moss or coco peat packed tightly in the pot for the first year or until the plant has developed a vigorous root system. HAPPY GROWING

6 Paphiopedilum and Zygopetalum (paf-ee-oh-ped-i-lum and zy-go-pet-a-lum) [A year in the shade house with John Steele and his orchids] January and February For the next two months, because of the continuous hot weather that we can expect, our orchids will be in survival mode for much of the time. They will not be making much growth on 40 degree days, and all we can do is take what steps we can to alleviate the harsh conditions. Moisture is lost, both by transpiration from the plants themselves, and by evaporation from the compost. This must be replaced by introducing humidity into the atmosphere, and watering the pots. The sun will be very strong, and of course the shading described for last month must be maintained. The aim should be to keep the leaves of the plants cool to the touch, and a fan blowing over them will improve air circulation. In my shade houses, the watering and humidity are taken care of by overhead sprays, which operate for three minutes twice a day, at about 5.30 am and pm. In their natural habitats, most orchids experience a drop in temperature at night, and the evening spray helps to imitate this. I do not operate the sprays in the middle of the day, as water lying on the leaves when the sun is high can act as a lens and cause scorching, even under shade cloth. An additional refinement would be to improve daytime cooling by using an evaporative air-conditioning unit, or foggers which produce such a fine mist that they don t leave pools of water on the leaves, and can therefore be used when the sun is shining. Once a week, I hand water the plants, at which time I apply half-strength liquid fertiliser, as described in my December notes. I am finding that many of my plants are affected by scale insects at present, and these are moved around very efficiently by ants, so that they even appear on the new growths of the Zygopetalum. Fortunately, the Paphiopedilum don t seem so susceptible. Much as I dislike using chemicals in the shade house, I shall be spraying with Malathion and white oil to kill both these pests. Use a mask to avoid breathing in the spray, do not spray in bright sunshine, and be careful not to allow the liquid to remain in the new growths of Zygopetalum, as the developing leaves will be damaged. March Now that the worst of the summer heat is over, we enter a more exciting time for these plants. Already, buds are showing in plants of both genera, and we have to be more careful of overhead spraying. Except when temperatures have been particularly high during the day, I have now dispensed with the evening spraying for the Paphiopedilum, as if water rests in the growths overnight, the newly developing buds can rot off. Zygopetalum send up their flower spikes with their new growths, and although the spikes are more resistant to excessive overhead moisture than the Paphiopedilum buds, the new growths themselves can rot if water collects in them. Maintain the summer shading at this stage, and continue to ensure that none of these plants dries out, feeding once a week with half-strength (or less) liquid fertiliser. At this time of year, I change to a fertiliser that is lower in nitrogen and higher in potassium, for example Growth Technology s Orchid Bloom Focus. April More buds are showing now in plants of both genera, so make sure that they have space to grow without being obstructed by the plant s leaves, or those of nearby plants. Insert thin canes near developing spikes to mark their positions. You have probably waited at least a year to see a plant bloom, so you want the flowers to be displayed at their best. Continue to fertilise the plants as you did last month, and ensure that moisture does not lie in the growths overnight. Overhead spraying in the morning will still be beneficial, but only while temperatures remain warm, and reduce the frequency to perhaps every other day or less to encourage strong root growth before the winter. By the end of this month, I shall be removing the extra layer of shade cloth that I put over the Paphiopedilum for the summer. May, June and July This month my notes cover most of the winter During May, all additional shading should be removed, ideally leaving no more than 50% shade. In my case, the shade house containing the Zygopetalum is permanently covered by 70% shade cloth. Both genera will be producing flowers over the next few months, and by the end of May they will have received their final dose of high potash fertiliser. No more feeding of any kind will be done until August. My larger shade house, which contains the Paphiopedilum, has a Solar weave roof in addition to the shade cloth, and by the end of May I will have added a polythene liner inside the shade cloth on the two most exposed sides to keep out the wind and driving rain and create more cosy conditions for the plants. Any plants blooming in the open shade house are moved into this house to protect the flowers from damage. A circulating fan can still be of benefit by preventing moisture settling on the leaves and flowers, but because mine is in the exposed apex of the shade house, I shall be turning it off and covering it up to protect it from the weather. One of the problems of a shade house without a waterproof roof in the winter is that the plants generally receive more water than they should, bearing in mind the cool night temperatures. They will, however, survive these conditions, provided that the compost is in good condition and the surplus water can drain away freely.

7 Paphiopedilum and Zygopetalum - continued August Well, winter arrived as expected whilst I was away enjoying the summer weather in England. My plants have had to endure some cold nights, although I am close enough to the ocean not to be troubled by frosts. Unfortunately these low temperatures, coupled with rainy conditions, have caused some damage to the flowers. Despite the protection of a roof and partial polythene lining, water accumulated in the pouches of some of my Paphiopedilum, causing them to rot. This was very disappointing, as these flowers can usually be relied upon to last 2-3 months, and are very useful for shows and displays. The Zygopetalum seem to be resistant to water damage, and their flowers have remained in good condition, with plenty more spikes showing. Where Paphiopedilum. buds are still developing, place a thin cane behind each bud and tie the stem near the base to encourage it to grow upright. The final tie is placed just below the ovary, once the flower has opened. Be careful to keep the plant facing the same way as the inflorescence develops, so that the stem doesn t twist towards the light. Zygopetalum spikes are pretty robust, but insert a stake to keep overhanging leaves away from the stems to allow them to grow vertically. Tie the flower stems to the stakes when transporting the plants. The good thing about the winter rain, of course, is that it fills up my water tank, and I am able to use this for all my watering. Fertilising will not be resumed until the end of the month, by which time some new root growth should be evident. September This month, I shall be starting to repot non-flowering Paphiopedilum, as I like to give these plants fresh compost every year. My usual compost for Paphiopedilum, which are typically in around 100 mm pots, consists of one part medium bark, two parts small bark, one part perlite and a quarter part shell grit. Before mixing the compost, it is a good idea to moisten the perlite so that you don t inhale the dust from it. Most of these plants do not make very extensive root systems, so they can be repotted into the same size pots again. However, be guided by the roots, and where they are vigorous the plant can be moved up a pot size. Plants which are in bloom will be repotted as soon as the dead flowers are cut off. As the month progresses, the light will become stronger, and I shall be increasing the shading from its winter level of 50% to 70%. In the summer, it will be increased still further. The plants will tend to dry out more quickly now, and will need watering more often to keep them moist. Weak liquid fertiliser can be applied every couple of weeks at this stage. Quite a few of the Zygopetalum are now in flower, but those that are not can be repotted if they need it. You can use your favourite cymbidium mix for these plants, which have vigorous root systems, and will benefit from being potted on as the roots fill the pots. Large plants with multiple leads can be divided, as you would cymbidiums. As the roots become more active, apply weak liquid fertiliser weekly. My plants grow in a 70% shade house all year round, but would probably prefer 50% in winter. October and November At the time of writing this in early October, the days are starting to warm up, but the humidity is still fairly high, so I have not yet set my overhead sprayers to operate automatically. I do occasionally operate them manually early in the morning when a particularly warm day is expected. By the middle of the month, I shall set the under-bench sprays to come on early in the morning for three minutes on three days of the week to ensure that humidity is maintained without soaking the plants. By the second week of November, the overhead sprays will be set to operate early in the morning on three days of the week, increasing to daily by the middle of December. Once a week, I apply half-strength liquid fertiliser by hand watering my plants. I prefer to use rainwater for this, but unfortunately my tank is not large enough to enable me to keep this up all through the summer. Shading is now at a level of 70% on both my shade houses, and the overhead fan in the house with a solar weave roof is switched on during daylight hours using a timer. An additional layer of shade cloth will be suspended over the Paphiopedilums when the sun is directly overhead in the summer. December As with most genera, repotting should be finished now, to allow the plants time to establish their new root systems before the really hot weather sets in. There will always be some flowering plants that have to be left until the last minute, but I have recently cut off the last of the exhibition hybrid Paphiopedilum blooms to enable the plants to be repotted. You can enjoy the flowers in a vase in the house where they last very well. I repot my Paphiopedilum into fresh compost every year, whereas the Zygopetalum will last a couple of years or more, as long as they are not pot bound. Careful attention must be paid to watering now, as plants can dry out very quickly on hot days. Neither of these genera should be allowed to completely dry out at any time, particularly the Paphiopedilum, which have no pseudo bulbs in which to store moisture. My overhead sprays will be operating for three minutes early every morning this month, and once a week I will be watering by hand to apply half-strength liquid fertiliser, such as Growth Technology s Orchid Grow Focus. My large shade house, where the Paphiopedilum are, has a solar weave roof, so I have a fan blowing over the plants all day to ensure good air circulation and prevent heat build-up. The Zygopetalum are under 70% shade cloth only and rely on natural air movement. Finally, a word about shading Paphiopedilum. These plants have quite a low light requirement, and I believe that even 70% shade is insufficient. Last summer, I suspended an additional layer of shade cloth above the Paphiopedilum, and had better results than previously. Of course, you must make sure that water from the overhead sprays is not prevented from reaching the plants.

8 This concludes my series of articles covering a year of growing these plants. I must emphasise that I have described the way I do it there are plenty of other ways, and you need to adopt methods which suit your conditions and local climate. Watch the plants carefully, and they will give you clues as to what they need to improve their growth. PAPHIOPEDILUMS Notes by Trevor Burnett Introduction Paphiopedilums are more commonly called "the Slipper Orchids" The name derives from the shape of the slipper pouch. The leaf may vary from rich green to very attractive mottled leaves. The flowers can last for a long time, four to six weeks even as a cut flower. These notes are general and should be adapted to the cultural environment in which your orchids are growing. Of course, specific cultural requirements to particular type or species can be sought from many resource books. Position Paphiopedilums require somewhat more shade than other types of orchids and burn severely if given direct sunlight. Paphiopedilums should be kept just moist, nor should they be watered in such a way to leave an accumulation of moisture in their crowns by nightfall. Watering Water only on sunny days. If the weather is cool, cloudy or rainy, you'll be much better off waiting a day or two before watering. Water early in the day. This will allow any water that got in between leaves or new growth to evaporate before nightfall. If it has been an extremely hot day I may give a three minute misting overhead about 5pm just to create some humility. Even watering this late the leaves will dry very quickly. Water from the top till the water runs freely through the drainage holes or immerse the plant in water up to 1/2" or so below the rim and let it absorb water for 10 minutes or so. This is okay if you have 6 or so plants and have the time. If in doubt whether you should water or not DON T. Light Not only are Paphiopedilums attractive to beginners because they are compact, attractive plants, but also because they can be grown successfully without any specialised facility. Plants will tolerate medium light intensity (slightly more shaded than Cattleya conditions) for the balance of the day. As always, light intensity and temperature are related; the hot mid-day or afternoon sun will provide terrific light, but will also cause the leaf temperature to soar, with resulting burns. Temperature In nature Paphiopedilums can be found in regions ranging from sea level to higher altitudes in the mountains. There are two groups of Paphiopedilums with respect to temperature requirements. The warm growing or mottled leaf types which ideally require a minimum temperature at nights of not less than 13 degrees Celsius. (Maudiae) The cool growing or green leaf types which will tolerate a much lower scale of temperature. (exhibition Paphiopedilums) However, most green leaf types have been adapted to grow in much warmer environments than the ideal. In either case, day temperatures should not exceed 35 degrees Celsius. As we know with our climate we quite often get days in excess of the desired temperature so we need to water the shade/glass house heavily in the morning to: Cool down the area around the plants; Create some humidity before the days temperature rises. Plants will not die when exposed for short periods of time to even higher or lower temperatures, but their growth may be diversely affected. Humidity and air circulation The plants are relatively slow growing compared to other genera and have bulbs to store water so the aspect of humidity plays an important part of healthy plants. Therefore, the humidity in summer month should be maintained were possible to prevent transpiration (leaf water loss) at a minimum. If low humidity is a problem, watering and misting are effective ways of increasing humidity or hosing down the growing area. Potting containers and potting mix A variety of containers may be used for Paphiopedilum culture. However, the two most frequently utilised are clay and plastic pots. The basic difference culturally in the two types relates to the rate at which they dry out. Hence, the grower must adjust his watering practices accordingly. I would not try and mix the two types of pots together. Paphiopedilums basically like a mix that allows for the circulation of air through the medium and a mix that does not become soggy. Sample Mix that I find works well. 4 Part Medium bark 1 Part charcoal 1 part polystyrene or perlite Add to the above some dolomite lime and fertiliser.

9 There are many potting mixes that will perform very effectively so the trick is really to find one that works in your conditions and stick to it. Paphiopedilums benefit from new mix and should be repotted at least on an annual basis for small pots and a bi-annual basis for larger pots 5" and above for best results. The plants can basically be repotted any time of the year. I personally like to have the small Paphiopedilum in new mix heading into winter. Fertiliser During the growing season, a soluble fertiliser use NPK can be applied every month at the rate of 1 teaspoon to 8 1 litres of water. Remember that the roots of Paphiopedilums are highly sensitive to excess salts in the medium. Be certain to leach thoroughly water between fertiliser applications to minimise the accumulation of salts, which can cause root tip burn. What is meant by the above ratio : N = Nitrate Content 30kg per 100kg mix; P = Phosphate 10 kg per 100 kg mix; K = Potassium 10 kg per 100 kg mix. Nitrogen promotes growth; Phosphate promotes flowers; Potassium promotes sturdy structure and tougher plants. Problems New growths are smaller, are stunted, do not grow upright: The plant is under stress, either because of weakened root system or insufficient light or too extreme temperatures, deficiency in nitrogen, or a combination of these. Repot the plant; check light, temperature levels, fertilizer dosage. Leggy plants growing tall: May indicate plants are not receiving sufficient light (they are stretching themselves to reach the light). Solution Move plant to different section of greenhouse. Tips of leaves are brown or spotted: Plant is not absorbing enough water either because of insufficient watering or because of root rot. Repot plant in new mix and add sphagnum moss or course sand around remaining roots Leaves turn yellow, then brown and die: Probably due to fungi as a result of excessive watering, soggy or decaying potting mix and/or excessive humidity possibly combined with too cool temperatures. Unpot the plant, treat it with a fungicide, cut dead / brown growth and leaves, repot in fresh potting mix. Allow the plant to dry in between watering. Watery spots on leaves that turn brown or grey or black, sometimes with yellow on the margins: Usually result from bacterial infection. Repot plant, treat plant with a fungicide, and keep it on the dry side for a few weeks. No or limited new growth: May result from nitrogen and/or phosphorous deficiency, or damage / rotting of growth buds (at base of previous growth), or setback if the plant was divided and left with only one growth. (Note: If plants or portions of plants are infected by bacteria, take immediate action as the infection can spread rapidly and kill the plant. Unpot the plant, remove all affected area, treat with a fungicide/bactericide, or some home-made solutions, repot in fresh media.) Plants have lost Roots Repot into sphagnum moss until roots are revived. Do not fertilise for 6 weeks. Frost Water the plant heavily in the morning as soon as frost spotted. Paphiopedilum propagation Unfortunately Paphiopedilums are not amenable to mericloning, so the only way to obtain a top-class Paphiopedilum is to buy a division or flower out of good seedling crosses. Consequently, divisions of awarded plants are highly sought after and are therefore expensive; fortunately, most retain their value well.

10 Dendrobiums (den-dro-bee-um) Soft cane or nobile form During the 1950's and 1960's when WA growers began growing Soft Cane Dendrobium, very few had any real success in flowering them. The number of plants was very limited and these were lacking in substance, with very few blooming they soon lost what popularity they had. In 1970, a new range of plants became available, these had a greater range of colour and were easier to flower, these plants were introduced from the Yamamoto Orchid Farms and are usually referred to as Yamamoto Softcanes. These plants now enjoy enormous popularity. Culture is so important for the successful flowering of Soft Cane Dendrobium, we hope the following culture notes will help in growing these hardy, cool to medium temperature growers. Light Soft Cane's like plenty of light, if you are growing them in conjunction with Cymbidiums, they should be hung above the Cymbidiums preferably under a minimum of 50% shade cloth, 70% during the hottest months here in Perth. In cooler weather they may take full sun, but they will not take frosts. Ventilation As with all orchids they should have constant air movement with a continuous supply of fresh air, this help's to eliminate problems with Fungus and leaf spotting. Watering It seems the key to successful flowering is great supplies of summer water and fertilizer (1/2 strength). Soft Canes during full growth (Spring & Summer) are gross feeders, but during their winter rest period they should be kept relatively dry, not totally, and no fertiliser at all. Regular watering during this resting period usually results in the plant giving keiki's and no flowers. Rest begins with the onset of cooler to cold conditions. About late May in WA. Fertiliser After the plant has flowered, use a popular brand of general purpose liquid fertiliser, applied at half strength as often as 3-4 times a week. This is followed by a low nitrogen 'flower booster' fertiliser from Feb to mid April. Once there are open flowers on the cane, begin again to slowly introduce fertiliser, starting with 1/4 strength liquid once a week then work up to your growing programme which is designed to bring on strong new canes. Never fertilise a dry plant. Potting The pot should be only big enough to accommodate the root system of the plant and allow for one more years growth. Smaller rather than bigger pots appear to be preferred by the plant. A general rule for the growing medium should be a porous mix of medium grade Pine Bark or similar. Experienced growers may prefer their own mix for their particular growing conditions. Flowers The flowers are made up of clusters of two to four blooms, which appear, often from leafless canes and sometimes for several years from the same cane. Various species and hybrids are known to bloom from spring to late summer.

11 Some reasons why orchids won t flower Reason: Not enough sunlight (indirect), or poor light levels generally. Poor air circulation; too sheltered from natural breezes, hemmed in by other plants. Lack of care resulting in limp plants and a general failure to thrive Water. Too much or too little. Fertiliser. Too much or too little. Growing conditions not humid enough during growing season (usually August to December in W.A.) Pests such as slugs, snails, slaters (wood lice), cockroaches, caterpillars eat roots and or developing flowers, spread diseases. Sucking insects. Scale, mealy bug, spider mite, aphids etc. Damage new plant growth in particular. Potting mix too old and holds too much water. Do not plant orchids in the ground. Cold draughty conditions. Lack of sunlight during autumn/winter, combined with poor or over watering practices, are among the most common causes. Possible remedy: Move plants to a more open sunny position or give them longer exposure to indirect sunlight (all day). Reposition plants if possible. Orchids require good air circulation, particularly during hot or humid weather. Neglect often results from lack of knowledge. Ask other orchid growers, visit local nursery or library, or visit an orchid society. Orchids require slightly damp but never wet growing conditions. Almost instant drainage is ideal when watering. If the pot feels light when picked up - water is required. Fertilise weakly, weekly. Use fertilisers such as Orchid Food, Aquasol or Thrive at 50% of published rates for orchids or ornamentals. Slow release granules (6-9 months) are okay. Eg: Macrocote. Damp floors keep humidity high. Growing plants above ferns or other such dense plantings helps with humidity. Moving air is essential to prevent some pests and diseases in high humidity conditions. Regularly add two or three snail pellets to the top of the pot. Cockroach and other baits may have a short life span due to the regular watering requirement of the plants. Use regular garden insecticide under and over the plant leaves. Do not spray on hot days. Apply at rates for ornamentals. Confidor, Malascale, Pyrethrum and Neem Oil are good remedies. Old potting mixes cause root loss and lots of dead leaves. Replace potting mix every 2 years or so. Orchid societies hold annual public demonstration. Visit your local library or the internet for information on how to. Soils are generally not suitable growing mediums for most orchids because of the poor drainage and aeration. There are however some orchids that do grow in the ground such as Crucifix, Pterostylis orchids etc. These are known as terrestrials. Minimise cold draughts, particularly in winter or keep the mix slightly drier when cold winds blow. Avoid long day periods of shade (any season). Avoid very wet and cold conditions, particularly during winter. N.B.: Direct sunlight will burn the leaves and stop essential chlorosis resulting in poor or dead and dying leaves.

12 Why Humidity is Important to Plants All plants inhale carbon dioxide through their leaves. This gas is used in photosynthesis. As the plant opens its leaf pores to take in carbon dioxide, some of the moisture in the leaf can escape. Thus the plants sweat water vapour into the air whenever they breathe. Dry air causes plants to transpire moisture much more rapidly than does humid air. Water in the leaves evaporates very quickly into air, causing the plant to lose moisture at a rapid rate. When leaves begin to lose water faster than the roots can absorb it - disaster strikes. It is an evil the plant inflicts on itself, in self defence. In order not to lose more water to the air, the plant will almost completely close its leaf pores. This slows down the flow of moisture from the plant effectively, but unfortunately it also reduces the intake of carbon dioxide. Without supplies of carbon dioxide, the cells begin to die and the plant looks tired and ill. The important point to remember is that dry air pulls water out of the leaves faster than the roots can supply the leaves. Under these conditions, it doesn't matter how much you water such a plant it doesn't help. Over watering only reduces the amount of air in the soil and invites root rot. When plants have the right humidity they thrive, because they open their pores completely and so breathe deeply without threat of excessive water loss. When the air is moist, there is little water lost from the leaf. Damping down the benches and surrounds, also misting leaves will keep the air moist. Rapid temperature rises damage orchids too. It means that the plant's leaves become warm and physiologically active, while the root system in it's solid rooting medium, is still cold and consequently physiologically dormant. The active leaves are demanding large quantities of water and nutrients which the root system cannot possibly supply. Under these conditions, photosynthesis, transpiration and the other vital plant processes, are severely restricted and as a result, developing flower growth and new growth are damaged. Rapid rises in temperature on sunny days can be avoided by opening vents or doors early in the morning - and letting the greenhouse warm gradually. A humid atmosphere that is not moving, is particularly undesirable also. Damp, stagnant conditions encourage mould and bacterial diseases. A constantly moving, light and buoyant atmosphere keeps orchids vigorous and healthy. Elanbee Orchids