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March 2001 This Month ONT will focus on: "Growing Phalaenopsis in Pretoria" (A condensed adaptation of a talk presented by Herman Steyn at an ONT meeting). Please be patient while this page loads, there are many photos! Written By Mr. Herman
Steyn.
Phal amabilis - (Grown against the wall) 1. INTRODUCTION The word Phalaenopsis refers to something butterfly-like. In some of the countries where these plants are native they are called "mariposos" which also refers to butterflies. Although they are striking tropical orchids they are just as easy to grow as African violets, providing a few of their cultural requirements are met. If this can be done they surely rank one of the most rewarding ornamental plants for house and greenhouse, especially when in flower.
2. PHALAENOPSIS AS HOUSE PLANTS A plant in full bloom will easily last, in perfect condition, for as long as three months in the home. During this time care should be taken to keep the relative humidity (RH), around the plants, above 60%. This can be achieved by spraying/misting the plants with water a few times per day or placing it on a tray filled with water and pebbles. Care should be taken to ensure that the plant does not stand in the water but above the waterline.
Most Phalaenopsis are shade-loving plants and should also not be placed where they receive direct sun. Light filtered through a lace curtain will do the trick. After you have enjoyed the flowering plant in the house it should preferably go back to the greenhouse where it can recover, grow and initiate more flowers to enjoy in your home.
3. PHALAENOPSIS AS GREENHOUSE PLANTS Unfortunately the largest part of South Africa lies in the sub-tropics and at high altitude where the winter temperatures and RH are usually very low. The only way to overcome these constraints is by means of a regulated environment such as the greenhouse. Phalaenopsis requires the following basic horticultural conditions for vigorous growth.
3.1 TEMPERATURE AND RH:
Day (max) Night (min) RH Summer 30°C 20°C 60-80% Winter 22°C 15°C 60%
As can be seen these temperatures are very realistic and should be easy too maintain except in winter when additional heating is required. Summer temperatures can be lowered, if too high, by means of a simple evaporative cooling system such as a wet wall. Try to keep the plants drier, but still damp, during winter. Remember to let your plants dry off completely before evening because water left standing in the crown or on the leaves will definitely result in crown rot or other fungal diseases.
3.2 AIR MOVEMENT It is absolutely essential to keep the air around the plants moving at all times. This will help to ensure that the plants are growing vigorously. Plants growing in well-ventilated conditions are generally also disease and pest free. Oscillating fans should be placed so that they don't stir the air too briskly or blow directly on the plants. Phalaenopsis does not like to be placed in drafts and they resent warm dry air from heaters.
3.3 WATERING AND FERTILIZING Because Phalaenopsis orchids are always in active growth, although it might slow down a little during winter, they always require a moist growing medium. These orchids do not have storage organs to carry them through dry spells, like Cattleyas and Cymbidiums, although their relatively thick roots and fleshy leaves might help them survive short unfavourable spells. Phalaenopsis are not very demanding when it comes to food. Plants can be fertilized every fortnight with a general horticultural fertilizer at recommended strength.
3.4 POTTING MEDIUM There are as many different potting media as there are orchids growers. I am fortunate enough to grow most of my plants in sphagnum moss, which I imported from the East.
Phalaenopsis - (On wire rack over water bowl)
Although a sizable quantity of my plants is grown in rockwool, of which there are a number of different brands. I have great success with both the above media. It is, however important to never let these media dry out completely otherwise it is very difficult to wet it again.
Phalaenopsis - (With speckled leaves)
Both these media should also be immersed in water before you start working with them. This is to prevent you from inhaling the harmful dust-like particles, which can be a serious health risk.
3.5 RE-POTTING AND DIVISION OF PLANTS I divide my plants as soon as:
Boil all tools in a kettle to sterilise
Plants are removed from their pots and rinsed in water to remove all dead and decayed plant material as well as stale potting medium. After this I soak the plants in solutions of insecticide and fungicide as a preventative against pests and diseases. Special care is taken not to break any of the healthy roots, which might die or rot afterwards.
Rub wet rockwool over a sieve to break up
Before re-potting or dividing plants make sure that all your tools and pots are clean and preferably sterilised. The tools I use for cutting are sterilised in an ordinary electric kettle by boiling them for 30 minutes or soaking it in a solution of Jik (2 parts Jik to 10 parts water) for 20 minutes.
Sifted, wet rockwool
The drainage holes of most pots are insufficient and I therefore enlarge the holes before using the pots. Plants for division are severed from the main stem just below a pair of healthy roots. Both pieces top and bottom, are planted. The top part, with the leaves, will quickly re-established and start growing whereas the bottom part usually takes a while before new growth starts. The top growth will flower within the same year but the bottom rootstock will probably only flower in two years' time. I have used the above procedure with great success and it is an easy way of increasing ones stock.
Dip plant in fertilizer "Coctail"
Sphagnum moss is used, as is, and wrapped around the roots so that it forms a loose ball. This, together with the plant, is then inserted into a pot, of which the bottom part is filled with limestone chips to help with drainage and air circulation. A layer of small limestone chips is also placed, as a top covering, on the moss to prevent the growth of green algae.
Roots with a mix of styrofoam chips and gravel
When planting in rockwool the procedure is a little more complicated. The wet rockwool is grated into small pieces by rubbing it over a coarse sieve or frame covered with chicken wire. It is then mixed with an equal quantity of Styrofoam granules and approximately half a cup of ordinary bone meal to every 5 litres of potting mixture. The plants are potted in the usual way with a top covering of small limestone chips.
Plant with cut leaves
The best time to re-pot or divide Phalaenopsis is just after flowering. If you decide to start growing these wonderful plants rather start off with a mature plant in full bloom. If it decides to die, you would have at least had a plant in flower for three months to enjoy.
Phalaenopsis root with leaves
H. Steyn P.O. Box 37100 Faerie Glen 0043 Photographs by H. Steyn and M. Wolter.
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