Growing orchids is not difficult, we must take into consideration certain fundamental parameters:
To resume the temperature requirements of the different orchid species, depending on where they come from, we can say that three main types of environment are necessary: warm, intermediate and cold. A warm environment is one that has a nocturnal (minimum) temperature above 18ºC and a diurnal (maximum) temperature of 30-32ºC. This is the environment needed for example by species of the genus Phalaenopsis. In the intermediate or temperate environment, the nocturnal (minimum) temperature should not fall below 15 °C, while the diurnal (maximum) temperature can be as high as 30 °C. This is the environment required by species of the genus Cattleya. In the cold environment, the nocturnal (minimum) temperature should be above 12 °C, while the diurnal (maximum) temperature should not exceed 24-25 °C. This is the environment needed by species of the genus Odontoglossum, the climate of the high tropical mountains.
Light is one of the most important parameters for plant health, and is directly related to the ability to produce flowers. Depending on the hemisphere in which we find ourselves, the north will be very cold and with less light, and the south will be warmer and with more sun exposure (in the northern hemisphere). So as a general rule, east/west orientation is best, while it is advisable to avoid north/south orientation. Extremes are not good and it is always preferable to maintain a dim but constant light. According to the behavior of orchids with respect to light, we can divide orchids into three main groups: those that live in the shade, those that live in full sun and those that prefer intermediate light. If we consider that most orchids are epiphytes, and live hanging in trees where they receive filtered light through their canopies, then we can say that intermediate light is most common. In turn, the amount of light that plants can and should receive is directly related to other growing parameters. For example, in summer, when temperatures are high and the sun is more aggressive, it is preferable to give the plants more shade, as it will be more difficult to regulate the temperature and humidity.
High air humidity is an indispensable factor for these plants, which usually come from tropical areas; the value should never fall below 50%. A rise in temperature leads to a drop in humidity, so during the hottest time of the year the humidity must be controlled with different systems. To achieve the necessary humidity, the orchids can be watered in the vicinity, water containers can be placed near the orchids, or shaded windows can be opened.
Constantly moving air is a good guarantee for orchid health. A small fan can help to maintain a constant and gentle current of air that eliminates excess humidity in the coldest moments and lowers the temperature when it is warmer. In a well-ventilated environment, plants can withstand temperatures a few degrees below the recommended minimum temperatures without great risk. The drop in temperature that always accompanies the increase in humidity, when there is no ventilation, promotes the development of fungi, for example Botrytis cinerea, a fungus that forms small black spots on the flowers. Good air circulation accompanied by suitable temperatures helps to prevent many of these situations.
How often should I water my orchids? The answer is a long one and to be precise, many factors must be taken into account: what type of pot the orchid is in, what type of cultivation method we are using, what species we are dealing with, whether they are adult or young orchids, in what environment we are growing them. It is essential to know the cultivation requirements of our orchids, especially with regard to their possible resting period. This period can be more or less long and its length corresponds to the length of the dry season in the place of origin of each species. The type of substrate used must always be taken into account, whether it is ferns, bark, moss, charcoal, perlite, etc., as they retain water differently. In general, orchids should be watered weekly, and during growth, the younger plants, as their root system is less developed and their vegetative apparatus more delicate, will need more watering and spraying, at least every two days. As for pots, plastic pots retain humidity better and longer than clay pots or baskets; they also prevent the roots from sticking to them. Taking all this into account, we can say that adult plants, grown in plastic pots, with bark, in a controlled environment, should be watered on average once every 5 or 6 days, and this frequency can be slightly increased or decreased depending on the factors mentioned above. Orchids should be watered in the morning, preferably in good weather, so that the excess water, which is hazardous to the health of the plants, has dried up before nightfall. Although most orchids prefer water containing little calcium, experience has shown that, except in special cases, any drinking water can be used, if possible by leaving it to stand for at least a day in suitable containers. For those who have the possibility of collecting water, rainwater is ideal, as long as it is certain that atmospheric pollution, which is becoming more and more widespread, has not changed its characteristics.
Except in special cases, which will be indicated for each genus or individually for each species, it is advisable to adhere to precise rules for supplying fertilizers whose formulas have been properly prepared. The most widespread growing medium at present is bark added to other more or less inert materials capable of retaining moisture (peat, moss, foam rubber), or of conferring greater lightness (expanded polystyrene, cork, lapilli), although these do not provide any nourishment for the plants. A fertilizer containing equal amounts of nitrogen, phosphorus and potassium (18-18-18), given dissolved in water at the rate of 1 g/L once a week for about ten months (from late spring to late winter), plus a nitrogen-rich fertilizer (30-10-10) for the rest of the year, which generally corresponds to the vegetative growth of most orchids, is sufficient nutrient supply to obtain vigorous, abundant flowering plants. Some prefer to use the nitrogen-rich formula (30-10-10) all year round, others use a formula richer in phosphorus or potassium, and others choose not to feed the plants during flowering or only do so once a month and so on. In any case, it is essential to implement a system and follow it, without changing it all the time. Do not forget that each formula has its components, and if we are changing the system all the time we will generate deficiencies in the orchids. Pay special attention if we use a substrate that is not inert, that is to say, one that contains some nutrient, as we should space out the applications a little more. Before fertilizing, it is advisable to water abundantly with pure water to wash away the residues of mineral salts and moisten the roots, preparing them for a new administration of fertilizer. The accumulation of salts can cause burns to the roots, especially if the medium is not sufficiently moist.
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