It has been observed that orchids often perform better when the water is somewhat acidic - having a pH of roughly 6.5. But this does not mean that they do not thrive in alkaline water. It has often been found that orchids also grow well with water having a pH of 7.5. Usually, the water supplied by most municipalities does not pose a problem for orchids. However, some exceptions do exist. Water containing elevated levels of magnesium salts and calcium may prove to be very hard and not form lather readily. As a result, the householder usually makes the water supplied from municipalities softer by passing it through a water softener. This helps to replace magnesium and calcium with sodium. Although large amounts of sodium are not good for the health of orchids, they have a preference for untreated water. In some areas, water supplied by the municipalities contains elevated levels of solutes or dissolved substances, which can have an adverse effect on the flowering of the orchids, especially their growth. This water can only be improved by putting it through a process called reverse osmosis, wherein pressure is applied to the water via a membrane. Consequently, two different lots of water are obtained - one lot containing very low amounts of solutes, while the other lot contains extremely high amounts of solutes, more than what was present in the water originally. The second lot of water with elevated levels of solutes is eventually discarded. While such setups are quite expensive and they also result in wastage of lots of water, several growers continue to use them for the health of their orchids. Even rain water is suitable for orchids, provided it is collected and stored properly. However, collecting rain water from a galvanized steel roof that has not been painted is not suitable for orchids, as it may cause zinc toxicity. In comparison, perhaps metal roofs that are painted are somewhat safe. This is, however, only true if the manufacturer of the paint used for painting the roof confirms that their products can safely be used on surfaces that are used for collecting drinking water. In addition, even water that is collected from the different types of plastic coverings that are used on greenhouses should be considered safe for orchid flowers. Nevertheless, it is best to store the collected rain water in a tank that is properly covered. This will protect the water from leaves as well as debris carried by wind. Such debris may contain micro-organisms that are responsible for various diseases, especially phytophthora and pythium. The flowers are infected by these diseases when they come in contact with the contaminated water.
Scanty watering may stunt the growth of an orchid flower. However, this is not something related to how often you water your plants. Orchids that need drying out between two waterings should always be dried out. However, when it requires watering, you need to do it properly and adequately. If you want to grow orchids, it is essential that you work out the logistics related to watering the plants, both grown at home as well as in a greenhouse. When you are watering your orchids, ensure that the potting mix is thoroughly wet. It is advisable that you place the container in a sink so that the surplus drains out without creating a mess. Alternatively, if you are watering the plant at the place where it is positioned, ensure that you remove the surplus water so that the flower never stands in water. Generally, you will not be able to gauze the conditions below the surface of the medium in the pot from outside. Therefore, stick a finger into the mix for better indication - this way you will know whether the plant has been watered well or it requires more watering. It appears that epiphytic orchids that require drying out after watering grow better when there is a short drying cycle. As a result, they need to be watered more often. In case, the flowers of epiphytic orchids are regularly wet for a prolonged period, not sporadically, they face the risk of losing their roots. Hence, it is essential to adjust the growing environments of these plants. When you are growing orchids at home, it is usually difficult to fine-tune their watering regimen. The humidity in the home is generally low and it results in the potting mix's surface to dry out faster. At the same time, the relatively lower intensity of light inside your home denotes that the flowers do not absorb the usual amount of water required by them. If you are employing a hose in a greenhouse, it is advisable that you return to the pot you have watered within about 30 minutes and water it again. You may even water the plant for a third time. Alternatively, you can use automated overhead sprinklers, as they will save time and labor. In fact, many commercial orchid growers use them.
When a plant is overwatered or watered excessively, it will not be able to receive sufficient oxygen in the region of its roots. We are aware that roots absorb oxygen to transform the accumulated sugars made through photosynthesis into a viable energy through a process known as respiration. During the respiration process, plants utilize the oxygen absorbed by the roots to turn out carbon dioxide (CO2), which is exuded by the roots. Absence of oxygen in the region of the roots couple with carbon dioxide, which is not removed from the potting mix, usually results in root rot. Eventually, this leads to the death of the plant. Very often watering can also result in the leaves of the plants to turn yellow and shrink owing to starvation, as this prevents the release of the stored nutrients. Amateur growers or those who have just started growing orchids may panic when they see this and may believe that shrivelling of the leaves is an indication of too less watering. As a result, they would generally increase the problem by supplying more water to the plant. However, if they inspect the roots of the plant they will notice that they have begun to rot by turning squashy brown or black. In such instances, it is advisable that you should stop watering the plant until the flower dries out. Excessive watering, however, helps to break down the organic potting mixes faster, worsening the condition, as this results in retention of more water in the region of the roots. Orchid growers who have a propensity to water their plants excessively can, however, adjust the potting mix with a view to suit their tendency. In addition, to a certain extent, clay pots are also helpful doing away with the problems related to overwatering. Aside from excessive watering, orchids can also be damaged if you water them from above like watering with a hand-held can or an overhead sprinkler. If the orchid leaves are soaked with water, they can result in various problems. In fact, if water stands inside the crown of orchids like phalaenopsis, in the leaves or any softer, new growths of the plants, it may result in rot. Moreover, when plants are watered from above, it may also lead to deposit of calcium, iron or magnesium contained by the water on the foliage, thereby diminishing the photosynthetic ability of the leaves. Ideally, you should ensure that the water is directed to the potting mix instead of the leaves. Tip the pots of plants having a propensity to accumulate water in their crowns forward permanently. This will allow the excessive water to overflow. In the nature, the flowers grow in a somewhat tipped manner and, hence, this should be ensured when you grow them in your home or in a greenhouse.
Providing your plants with lesser amounts of water than what they require may lead to various problems. However, the problems associated with underwatering are not as severe as those associated with excessive watering. The results are very damaging, perhaps worst, when you sprinkle water on the potting mix. Watering the plants in this manner wipes out plant's motivation to develop deep roots. This is mainly because water seldom, if ever, reaches the bottom of the pot. At the same time, salts present in fertilizers and those dissolved in water accumulate in the region of the roots and also remain in the potting mix because water does not drain when you sprinkle it just on top of the mix. This may eventually prove to be highly toxic for the plants. On the other hand, if water, especially unadulterated rain water, is allowed to completely drain through the pot at least once every month, it will leach out the accumulated salts. In other words, it will serve as a healthy flushing process. Underwatering may also happen even when watering is done in a proper manner - both thoroughly as well as deeply, but essentially not very often. When plants are underwatered, their roots shrink, become grey and also brittle. In such situations, you can fine tune the potting mix by adding materials that can retain more water. Interestingly, if you water your plants infrequently, you may use plastic pots, which possess the ability to hold two time more water compared to the clay pots.
It is possible to rescue overwatered plants provided you notice the problem right in time. In case the potting mix has deteriorated badly, you need to repot the orchid using something that is coarser. If the roots of the plants have been destroyed, they will recuperate much better if they are misted and kept in highly humid conditions instead of watering them. Provided you take these measures, you will find that the plants will regenerate new roots soon. On the other hand, if the plant does not have any viable roots, it may really be a difficult task to save the plant. Remove the rotten parts of an overwatered plant using a sharp knife and dust the remaining parts with sulfur. It is best to keep a damaged plant in a transparent, covered, plastic sweater box containing moist sphagnum moss at its base. The plants should be kept in this condition for some weeks till new roots appear. You need to mist the plant from time to time in order to maintain the humidity level. Also keep a small gap for ventilation by placing the lid slightly loose and ensure that you do not keep the plant in bright sunlight. Similarly, it is also possible to revive dried out plants that have suffered underwatering. The dry roots of such plants can be revitalized by treating them with high humidity conditions. Keep them in a transparent plastic box containing moist sphagnum moss and out of direct sunlight.
Water temperature as well as timing is very important for the health of orchids. Applying cold water, less than 50�F, will kill the root hairs. Moreover, such cold water will also result in the collapse of the cells in the leaves if the water is splattered or sprayed from the top, especially in plants that love warmth - for instance phalaenopsis. Moreover, you need to know that cold roots will not absorb water or nutrients. Hence, it is advisable that you always use water at room temperature. It is also important that you water the plants very early in the day, as this will help the leaves to dry out and the root ball to get back to moderate temperatures, for instance the temperature in the surroundings, much ahead of the cold damp night. If the leaves do not dry before the night, the dampness may invite fungal as well as bacterial diseases.
Generally, nearly all types of tap water are suitable for growing orchids. In fact, you should not be too worried about the water quality unless you find any other perceptible reason for your plants to become weaker. It has been found that orchids usually grow better when they are supplied with water that contains small quantities of dissolved salts, for instance any good quality tap water. On the other hand, they do not grow as well if you provide them with distilled water. However, the quality of water differs from one place to another vis-�-vis their pH levels, and chlorine, mineral salt as well as other solid contents. In case the extent of dissolved salt surpasses 300, you need to use an alternative source of water for your plants. Rain water is an excellent source of water that can be used for your orchids. Usually, rain water contains extremely low amounts of dissolved mineral salts. Several orchid growers vow that using rain water for their plants have yielded excellent results. In fact, orchids are especially sensitive to salts, for instance phragmipediums and masdevallias. On the other hand, using rain water to grow orchids also has its downsides. One of them is the fact that it may result in calcium, iron and magnesium deficiencies in the plants even if you try to supplement these essential minerals through fertilizers. This is mainly because most fertilizers do not enclose these minerals, as manufacturers take it for granted that they will be provided in adequate amounts by the water supplied to the plants. This problem can be solved easily by adopting two measures. You may use tap water for the plants once in every fourth watering. Alternatively, you may mix some tap water with rain water and use the blend to water your orchids.
Here is a word of caution for all orchid growers. Never use water that has been "softened" to grow your orchids. The typical water softeners we use at home function by removing magnesium and calcium ions, which are replaced with sodium. In fact, sodium is much more toxic for orchids compared to calcium and magnesium. Preferably, you should tap into the water supply line using a "T" spout for obtaining water for growing orchids even before the water can enter the softener. In case this is not possible, try to "deionize" the water. You can use "deionizing" techniques like a water softener with a "weak acid" ion-exchange resin. Alternatively, you can also use the "reverse osmosis" technique. Although this process leads to wastage of plenty of water, it is effective in removing as much as 99 percent mineral, ions, contaminants dissolved in the water as well as hardness.
Usually, the pH level of water used for growing orchids can vary from 4.0 to 7.5. The optimal pH level should be between 5.5 and 6.5. However, it has often been found that some orchid growers use water with an elevated pH level - as high as 9.0. Although such water is extremely alkaline, it does not cause much problem. Universally, the neutral pH level is 7.0 and anything lower than this is acidic, while a pH level above this is alkaline. Optimal pH helps to enhance the availability of useful fertilizer elements, while lessening the plant's absorption of detrimental elements. Extreme levels of pH, which is under 4.0 and higher than 7.5, may be responsible for making many nutrients inactive. Perhaps orchids are able to endure extreme levels of pH compared to several other houseplants because they have evolved in environments that are poor in nutrients. As a result, orchids can survive even when fertilizers are not available when the pH levels are extreme. The pH levels of typical rain water are usually suitable for orchids. Generally, rain water is somewhat acidic having a pH of roughly 5.6. If the pH of water available in your locality is high and it needs to be lowered, it is advised that you use any citric acid. For instance, grapefruit juice is perfect for this purpose. However, you ought to keep in mind that adjusting the pH level usually adds ions to the water and this may cause the plants to burn up. On the other hand, it is difficult to adjust hard water, because municipalities generally add pH buffers to the water supplied by them.