CHAPTER 2

The Paphiopedilum Grower’s Manual

CHAPTER 2

When and How to Water Your Orchids

A PLANT’S GROWTH IS DETERMINED IN DIRECT PROPORTION TO THE AMOUNT OF WATER IT RECIEVES.

This is not a theory waiting to be proved…it is a fact. You can see the results of this in everyday life. If you would like your orchids to grow large, healthy and robust, give them plenty of water and they will respond accordingly. Water them often and they will just keep growing. BUT!

But… read further to learn the details of the procedure, and to understand what else is necessary to grow those magnificent plants yourself. These following principles are tested and proved, in homes and in greenhouses around the world. They have been adopted by countless orchid growers who applied them to many different kinds of orchids in their collections. The fact that numerous other authors have now adopted these same methods is proof that they do indeed work, and many species of orchid plants in many collections have benefited from renewed vitality and vigor. You can achieve this same success.

"When should I water my plants?" This question is asked by every beginning orchid fancier.

The correct answer is of course, "When they need it."

Unfortunately, this answer does not begin to satisfy someone who is having great difficulty trying to understand how often to water his plants, especially since everyone he talks to tells him something different. Because of the many types of growing media, climates, greenhouse or in-home conditions and individual microclimates, there are probably no two persons doing the exact same thing with their plants. One must know all the variable conditions in order to advise a beginner correctly.

If the conditions for sufficient air movement are NOT provided, the single most frequent cause of death of most orchid plants is from improper watering techniques. Anyone wishing to raise orchids should be fully aware of the influence water has upon the success or failure of his endeavor. If you wish to cultivate these beautiful orchids, then you should also assume the responsibility for their successful culture, and it is essential that the dangers of improper watering techniques be thoroughly understood and be avoided in order for the health and survival of these unique plants to be maintained.

Following are specific elements which will help you to understand what happens when you water your plants.

HABITAT CONDITIONS

In both literature and horticulture, many orchids are referred to as terrestrial plants. Yet some species grow upon trees with their roots embedded in mosses and lichens, and like the American laelias, they should be termed epiphytic orchids. Many species grow lithophytic in mosses on rocks, and some even grow upon the soil. This however, does not substantiate their being called terrestrial orchids.

Those found growing on the ground actually have their roots coursing throughout the leaves and detritus of the forest floor, and seldom do the roots penetrate the true soil. The plants found with their roots in soil often appear to have had that soil washed or fallen over them, after having been first established in that particular growing spot.

In view of the growing conditions I have personally observed in numerous different habitats, I regard most all orchids as epiphytes; and if you view them as such, your success in their culture will be greatly enhanced. If you remember that epiphytic orchids are those found growing in mosses on trees, they are subjected to constant air circulation and they dry rapidly after a rainfall. With this in mind it should not be difficult to understand the basic concept for watering your orchids.

Most habitats of orchids are subjected to prolonged periods of heavy winds and rainfall, in certain parts of the world they are called monsoons. Some regions have both a wet monsoon and a ‘dry’ monsoon (less rainfall), others only a wet monsoon. Monsoons are large-scale wind systems and they are seasonal and predictable in their time and direction. Regardless of the fierceness of these wind or rain storms, many plants and animals depend upon them and have adapted to their cycle.

It is even possible to examine the plant structure of some species of orchids and to guess rather accurately, the general area from which they originate, or at least the climate in which they can be found.

For instance, some Paphiopedilum species have only a few, long roots, and have thin leaves which are fairly short. Small bits and pieces of detritus will be found clinging to their roots. These species often inhabit a cloud forest, out of the path of the monsoon, and they are subjected to heavy clouds and continual moisture vapor from the nearby sea. Plants inhabiting areas with abundant and continual moisture do not need a large root system, nor do they need thick or large leaves for water retention during a prolonged dry season.

On the other hand, a species like P. godefroyae, found growing at sea level in the Gulf of Siam, has many very thick and succulent leaves, and its huge mass of thick roots weighs much more than its leaves. Judging by the plant, one would think that it comes from the desert, not from one of the most humid places on earth. But, while there are seasonal periods of long and heavy rains in the gulf, it is also a place where almost no rainfall will occur for five or six months. Knowledge of climates can be very helpful in governing the way in which we grow our orchid species.

Throughout most of the areas where orchids grow, humidity constantly remains high and they receive much of their moisture requirements through their leaf pores called stomata. Unlike other kinds of plants, orchids have fixed stomata, which always remain open, and they cannot regulate the amount of moisture they gain, or lose.

In habitat, when temperatures rise during the day, the ambient humidity is readily assimilated, and growers living in these regions might not irrigate their plants for several months. In fact, they find it necessary to protect their plants with an overhead shelter to prevent any rainfall from reaching them, thereby causing them to rot. A large number of orchid growers from these regions grow many species of their orchids in wooden baskets or in clay pots, with no potting media. The pots or baskets are used simply to confine the orchids and to give their roots surfaces to which they can attach. With so much ambient humidity, the ideal conditions also exist for fungi and bacteria, and these precautionary measures must be taken to prevent diseases from gaining a foothold.

In the home, or especially in a greenhouse, too much humidity would be a problem unless large volumes of air could be circulated to keep surfaces dry after irrigating. In order to keep the plants healthy, a small gale would have to be maintained inside the growing area. Fortunately, the real problem seems to be in trying to maintain enough humidity in most domestic growing spaces, so this is not a common problem. It does however, serve to illustrate the needs of these plants.

Plants of many orchid species have leaves which are thick and numerous, and they have pseudobulbs (not true bulbs because they grow above the ground). Many species are found growing close to bodies of water and have their roots embedded in thick pads of mosses, which grow in water seepages on rocks. Even though they periodically are exposed to hot drying winds, sometimes for months at a time, the relatively small surface areas of their leaves restricts the water loss, while a massive root system and their close proximity to open water, enables them to gather and store every obtainable drop.

During the prolonged wet season, the mosses in which they grow are porous enough to allow air circulation to reach the roots, and they help to drain off excess water, thereby preventing the roots from decaying from lack of air. The orchid’s hard, often fleshy and wax-coated leaves are accustomed to excesses of moisture, and are not damaged by constant rains and high humidity.

If excessive water really was a certain cause of death to these orchids, none would survive the monsoon, nor even the heavy and prolonged convectional rains they are subjected to in habitat. Their adaptation to these prolonged wet periods is by growing in mosses and other freely aerated surfaces as their means of survival.

Each species of orchid has adapted to its own particular climate. While most species can be found growing on trees, and a much lower number can be found on the forest floor, some will even be found growing in mosses on rocks. They live mostly in regions with both high, and moderate levels of humidity.

While we cannot reliably maintain the same conditions to which each species has adapted, we can cater to the basic needs of these plants. Their needs are very simply, to grow in relatively high humidity, to give them a porous growing medium, and to keep them from remaining too wet by supplying sufficient volumes of circulating air.

WHEN TO WATER

No two plants need water at the same time. Because of a large number of variables, one plant will always dry out sooner than another. Factors such as; the size of the root system, whether or not the plant was recently repotted or if it needs to be repotted, the number of growths, the type of potting soil, if it is in a clay or plastic pot, the time of day and the time of year, the temperature, the humidity, the amount of light, the volume of air movement a plant receives and the weather forecast for tomorrow are all factors which must be weighed in order to properly gauge the time to irrigate.

The final answer to the question of when to water can only be learned after many years of experience. But, by taking the above considerations one at a time, it will help to answer some of those first questions, and it will give the beginning orchid grower a better understanding of how these plants function.

When an orchid has been recently divided and repotted, the roots do not function because they have been damaged. Applying water to these roots too soon or too often, can cause them to decay. Keeping them slightly moist will allow their recovery and will encourage new growing tips to emerge, therefore it is best just to mist a recently repotted plant daily for a week or two.

On the other hand, a root-bound orchid with multiple growths would need to be watered several times a week. It could be maintained by misting, but in order for it to grow and prosper, it would need pot watering. If either plant were potted in plastic, it would need much less water than if it was in a clay pot, since clay is such a porous container. And a ‘heavy’ mix, meaning one that is composed of small particles which retain more moisture, would require fewer irrigations than a ‘light’ mix would, because the latter would dry out much sooner.

Plants growing in high light intensities require more water than those in shadier places, since the sun increases both the ambient temperature and the speed of plant metabolism. Also, the greater the volume of air passing over each plant, the more it will dry out from evaporation.

If the weather forecast for tomorrow is for rain, perhaps you might want to wait to water until fairer skies are predicted, since during a rainstorm the relative humidity goes up significantly. Since it will be cooler and darker during the rain, plants will not be respiring at their normal rate and it would be best to wait.

If you missed watering your plants in the morning, it usually is best to wait until the following morning rather than to water them too late in the day and have them remain wet during the nighttime. In the summer, with high temperatures during the nights, it is not so much of a problem, but during the winter it could cause plant diseases to gain a foothold, frequently with disastrous results.

Keep this one thought in mind: Plants respond in direct proportion to the amount of water they receive. When properly potted in a healthy mix suitable for your particular conditions, you should be able to water your orchids twice a week or more, without fear of over-watering them. I have found that many orchids can be watered nearly every day when the weather is bright and sunny. All factors, particularly air circulation and potting media, must be in balance to allow for this, but it is not difficult to establish and to maintain once you get to know your individual plant’s conditions and needs. The results of frequent irrigations can produce growth in your plants which will simply amaze you.

HOW TO WATER

Orchid culture can be filled with shortcuts, but watering is the one area where they really do not belong. In a greenhouse it is easy to turn on the watering hose and water all the plants with a soft spray. They all get wet; you know they do because you can see all that water. Drenching them with water can be done in just a few minutes. But the proper method of watering your plants takes time.

Watering is the most important technique (air circulation is a condition, not a technique) in orchid culture, yet it is the most readily misunderstood. Most orchids can live with the ‘wrong’ temperature, the ‘wrong’ amount of light or be in the ‘wrong’ location. But few can survive if they are improperly watered.

You have to make a concentrated effort to water correctly, and it takes time to do it thoroughly. The rewards of seeing, or of showing a well-grown plant or a group of plants, are very satisfying indeed, and it should be high on the list of priorities of every orchid grower. Just being able to maintain a plant is not good enough these days; you should strive to do better with your plants every season. If you limit the number of plants you raise to those that you can care for well, then you will find the task much less forbidding. And if you do not feel that you have the time or inclination to water properly, then perhaps orchid culture is not for you.

Hand watering is most easily done with a ‘rose’ type-watering nozzle, which breaks up the flow of water without restricting the volume. With this attachment you are able to direct large amounts of water towards even freshly potted plants, without the danger of having them become dislodged. The flow should be full enough to fill the pot, and to flow freely out the drain holes at the bottom, yet without welling up within the pot and loosening or scattering the compost.

Even when you water plants on a growing tray or on a wire rack of sorts in your home, water the tops of the plants freely, as well as the undersides of the leaves, if that is possible. But do try to keep the water out of the flowers since it can cause them to rot. When you water with a wand, maintain a side-to-side, broad, figure-eight, or perhaps a circular motion, watering several plants at the same time, as it will allow you to complete your irrigation more quickly. The plants should be thoroughly soaked before moving on to the next group, and you should look for those which need watering from both sides of the pot.

This is only the first step in watering. The most important step is to go back and to repeat the irrigation a second time. This is called leaching, and it is what must be done in order to maintain healthy conditions in the pot. This step is the one most often overlooked, yet is the one step, which no one should omit.

Common sense tells us that it hardly would seem to make any sense to re‑water our plants; after all, they can only take up so much water at a time. It seems such a waste of time and water. But it is not at a waste when you understand what happens as you water your plants.

Each time you water your plants, salts (both soluble and insoluble) are deposited inside the pot, carried there by the irrigation water. Every irrigation deposits more and more salts which cling to the roots, the compost and to the walls of the pot as the water evaporates. Salts are found in water and in most potting soils, and are the components of fertilizers. Some of these salts become locked-up in the compost and cannot be released, regardless of how often you leach, in which case chemicals must be used to dissolve them so they can be eliminated.

Salts also can cause changes in the pH, which can lock-up needed nutrients and thereby depriving the orchid of these elements. Signs of excessive salt are: loss of roots, lower leaf drop, leaf‑tip die‑back, chlorosis, lack of vigor, premature flower drop and I suspect, loss of fertility. Each of these symptoms is indicative of other problems, but because salt buildup is such a frequent cause of plant troubles, you should look there first.

There also is another condition sometimes encountered in orchid culture, caused by excess salts, but its diagnosis is not readily apparent. Perhaps you have seen it. In a collection of nice looking and seemingly well‑grown plants, suddenly, a large number of plants will exhibit leaf‑tip burn, root loss and even mid‑leaf or crown rot. The effect will appear in different species throughout the growing area.

Some of the damage could be fungal or bacterial, but usually it is caused by a rapid increase in the concentration of salts within the pot. The condition is the result of growing the plants without periodically leaching the medium, and by allowing them to suddenly dry out when they are normally maintained fairly moist. This action causes an increase in the percentage of salt concentrations in the mix.

When the weather changes to hot and dry, or if an irrigation or two is missed, the water within the pots dries out more than usual, thereby it can raise the concentration of salts to a toxic level. The ensuing rupturing of plant cells either shows up as salt damage, or else it can allow diseases to enter, (masking the original cause of injury). Once the normal watering schedule is resumed, the damage seems to clear up, but the cycle frequently can be repeated a second or third time, never giving the grower a clue as to the real cause.

Damage from accumulated salts usually happens so gradually that it frequently is not noticed until it becomes widespread. It is unlike a rot, which can suddenly consume an entire plant. The cause of the salt damage cannot be easily determined, since there appears to be no relation between what seems to be your ‘thorough’ watering, and the leaf burn.

You should be aware of the potential for this damage to your plants, and be quick to remedy the situation. Realistically, it may not be necessary to leach at each watering, although it would be most favorable for your plants. Leaching can be done every third or fourth irrigation, or at any frequency consistent with the good health of your orchids. But, it must not be put off.

Chemicals are available to mix with the irrigation water, which have a residual effect, and after irrigation they continue to dissolve salts until the next irrigation when they will then be washed out. Phosphoric acid dissolves most of those alkaline salts, and is itself a fertilizer. Two operations at once can be performed by its use; however it can change the pH considerably so it must be used with caution. Where water is a restricted resource, perhaps greater use of chemicals can be made instead of frequent leaching in order to conserve water.

FERTILIZER

Many orchids do not seem to require fertilizers. Because they seldom if ever, exhibit the same signs of leaf yellowing that a Cattleya orchid does, it may seem hard to justify using any fertilizers at all. But experience has shown that most orchids do show improvement when fertilized, and it should be applied at a more reduced rate than that given other kinds of plants. Any good, complete fertilizer which is heavy in nitrogen, may be used at either one‑half, or one-fourth the recommended rate.

Although some growers have success with them, placing resin-encapsulated fertilizer pellets on the surface of the potting medium heightens the risk of root burn, and incorporating them into the potting soil is only slightly less risky. Fertilizers are best applied in liquid form through the irrigation system, to irrigate both the leaf area as well as the root zone.

All orchids potted in straight fir bark, as well as those grown in high‑light intensities will both require more fertilizer than those grown in compound mixes and under low-light conditions.

I would recommend fertilizing on a regular basis. This means at every irrigation. Dilution rates should be further reduced during the colder and non-active winter months, and discontinued for orchids which have a rest period. I would also caution that a close watch should be kept over the plants, and that remedial action be taken at first sign of damage from excess salts.

Fertilizer applied too frequently will show first, as darker green foliage, followed by soft and weakened growths. Too high nitrogen will usually prevent flowering. Damage from excessive fertilizer will usually be seen within a day or two of its application. New leaves turning black at the tips, and then rapidly traveling down toward the pseudobulbs or the base of the plant, is a sure sign of too much fertilizer. Keep in mind, that if those same over-fertilized plants were grown in higher light intensities, the same amount of fertilizer may be too little.

Fertilizers are not ‘magic’. But they are a very useful adjunct to our orchid growing equation. Used at the proper rates and frequencies, they can add a definite and noticeable ‘push’ to the health and appearance of our orchid plants. And the resulting production of flowers can be quite impressive, too.

QUALITY OF WATER

Every community’s water supply is different, even within the same city, and at different times of the year. The combinations and concentrations of minerals and trace elements, as well as the pH, vary from time to time and from source to source. Most are slightly alkaline, loaded with trace elements and have been treated (mostly with chlorine or chloramines) to make them potable.

A water pH of 7.0 is neutral; readings above that level are alkaline, and those below are in degrees of acidity. Your water district can give you details of your water quality and its components, or you might wish to test your own water supply, and you can obtain an inexpensive pH test kit from your local garden supply store.

Excess alkalinity in our artificial growing habitats can lock-up certain elements, and it can cause salts to accumulate faster within the root-zone. Alkaline water causes more problems for Paphiopedilum growers, despite the fact that many of the species are found growing on alkaline limestone. While it would appear that in their habitat, the limestone is a contributing factor to their nutritional requirements, in reality the mosses and leafy detritus into which their roots are imbedded are acidic. Since limestone is more readily dissolved in cold water, the warm tropical regions where Paphiopedilums are found growing cannot supply more than a trace amount of that substance.

Rainwater is either neutral or slightly acidic, having a range of 6.0 to 7.0, mostly the latter. Many orchid species thrive in the slightly acid range of pH. Very low acidity, in a range from 3.5 to 5, also causes certain chemicals to lock up and become unavailable to the plant, but on the other hand, it does not allow many salts to accumulate within the pot.

A neutral pH water source is best for our plants, since it causes the least number of problems. Most fertilizers can be used under such water conditions, without such frequent leaching as would be required with more alkaline irrigation water. Few chemical treatments would be necessary with a water supply having a pH below 7.0.

Small amounts of lime could be incorporated into the potting soil in areas with water of lower pH, to counteract that greater acidity. Potassium hydroxide could also be added to the water supply to raise the pH, while phosphoric or hydrochloric acid can judiciously be used to acidify an alkaline water source, the former being the first choice.

Fresh rainwater is beneficial to your plants; you can almost see them grow after they have been out in the rain. Stored rainwater does not seem to have quite the same effects, but it does have many benefits. One of them is its purity and an absence of salts. Rainwater is slightly acid, and because of this, it helps to dissolve those accumulated salts in potted plants. If collected from a clean surface, stored in impervious containers and kept from contamination, it will last indefinitely. A disadvantage of storage is that it either must be stored in a raised tank for gravity flow, or else it must be pumped mechanically.

Fresh water from wells or lakes can have high concentrations of dissolved solids, and it should be tested before being used on plants. Swimming pool water should never be used on orchids because of the high concentrations of chemicals used for its purification. Also, softened water from a home softener should never be used for plants, since most of the softening chemicals (usually common table salt), can be lethal to plants. This is particularly important to remember if you have ever watered your plants in the kitchen sink, unless your cold-water faucet (like many homes) is tapped to a non-softened source.

Mechanical means are available whereby water of the utmost purity can be obtained. Both de‑ionizing and reverse-osmosis machines filter out all the chemicals and impurities from the water, thereby delivering water as pure as distilled water. At the time when these systems first became available to orchid growers, it was thought they would solve the problems of salt burn and the excesses of unwanted mineral elements. As has been learned since, plants require many of the trace and macro elements which are removed from the water, although it is not known precisely in what quantities they are needed.

Unfortunately, many kinds waste a tremendous amount of water in the purification process. Another major disadvantage of these systems is their initial purchase price or their monthly rental fees, both of which are expensive. Another factor which precludes their use in greenhouses, but not for very small needs, is in the fact of the limited volumes they are able to produce and the length of time it takes to deliver the purified water. Additional tanks and pumps must also be maintained to collect and to store the water for its use.

While other crops have been grown hydroponically, orchids have seldom been successfully raised by such systems. They like to have fresh water at their roots, not that which has been used several times before. Collecting and re‑using water is fine for the conservation of resources, but one must be knowledgeable about its use, and to know how it can be treated for re-use, as well as when it must be discarded.

Extremely cold water should not be used on orchids and neither should hot water. It depends upon the interior temperature of the growing area. If the plants inside the greenhouse are at very low temperatures, very cold water could cause them some harm. On the other hand, if the inside temperature is warm, very cold water would not remain very cold for long, and therefore would not cause any damage. Water which is comfortable to your touch, even though it may seem cold, is suitable for orchids. Common sense can guide your decision.

To summarize, since you now know more about the effects water has on our plants, you can train yourself to be observant to the results of your watering practices. Learning when and how to properly water your orchids requires a studied effort; it will not just happen. Every time you irrigate your plants, you should also observe each plant individually, making note of its condition. The next time you observe the plant, either to irrigate or just to look, compare its condition to the previous visit. If anything has changed, is it because of the effects of water?

Study your watering practices and ask yourself questions such as: Do you always water about the same amount, or do you really pour it on one time, and then lightly dampen them the next? When you see some of your plants going limp between watering, or rotting, or doing beautifully, or poorly, can you correlate the problem to your watering methods?

Answers do not always come easily. You will have to search for them at first. But they are there, and since you have now learned how to understand the effects water has on orchids, your confidence and satisfaction at how well your plants are growing will increase as you find those answers. Your success at watering will be a satisfying, and very comforting reward.