What are the harms of orchid potting media and water being too acidic or too alkaline

Orchid growers in the north, to groworchidswell, there is an easily overlooked issue, and that is the acidity and alkalinity of the potting medium in the orchid pot and the pH value of theorchidwatering water used normally! When some orchid growers find thatorchidsare not growing well or are withering, they mostly look for the cause in fertilizer and water, ventilation and light,pests and diseasesand other aspects, often overlooking the acidity and alkalinity of the potting soil and the water used. According to relevant materials and the practical experience of orchid growers, the pH of orchid potting soil and water should preferably be 5.5~6.5. This is also a principle that orchid growers must follow. I. What is pH value. pH value is the negative logarithm of the hydrogen ion concentration in water. A pH value less than 7 is called acidic water, a pH value equal to 7 is called neutral water, and a pH value greater than 7 is called alkaline water. The method for measuring pH is very simple, mainly A: litmus test paper and a color comparison board. B: a pH meter or pen. II. The reasons for the harm of potting media and water being too alkaline or too acidic: Orchids are suitable for growing in slightly acidic soil (potting media). That is, a pH value of 5.5~6.5 is suitable! Too acidic or too alkaline is harmful to theorchid'sgrowth, and in severe cases can even lead to the death of the orchid plant. So why do too acidic or too alkaline potting media and water affect and harm orchids? 1. Potting media and water being too alkaline, that is, a pH value greater than 8, will produce the following adverse phenomena: A: Potting media and water being too alkaline will make the living environment of the orchid fungi that coexist with the orchid's fleshy roots harsh, reduce their reproduction, and destroy the balance between the orchid and the orchid fungi. This leads to poor orchid growth. B: Potting media and water being too alkaline will reduce the availability of trace elements in the substrate such as copper, zinc, manganese, and iron, making it difficult for theorchid'sroot system to absorb them. Orchids that do not receive trace element nourishment will suffer root growth obstacles and are prone to withering and dying. C: Potting media and water being too alkaline will also make it easier for ammoniacal nitrogen in the substrate to form ammonia gas and volatilize away, which not only causes fertilizer to be wasted but also prevents orchid roots from getting the nutrition they should have, resulting in poor growth. D: Potting media and water being too alkaline will make a large amount of phosphorus in the substrate easily combine with calcium, reducing the root system's absorption of phosphorus. This causes the root system to be increasingly severely deficient in phosphorus, and growth is hindered. 2. Potting media and water being too acidic, that is, a pH value less than 5, will produce the following adverse phenomena: A: Potting media and water being too acidic will increase the availability of trace elements in the substrate such as copper, zinc, manganese, and iron, causing poisoning of the orchid root system. B: Potting media and water being too acidic will turn the three major elements nitrogen, phosphorus, and potassium and the elements calcium and magnesium in the substrate into insoluble forms. The root system cannot absorb them, causing the orchid plant to starve, age prematurely, and turn yellow. C: Potting media and water being too acidic will make phosphorus in the substrate easily combine with iron, reducing its activity and affecting root development. D: Potting media and water being too acidic will reduce the activity of nitrifying bacteria in the substrate, limiting the nitrification of ammoniacal nitrogen, causing root poisoning, with the resulting roots being short and thick and appearing brown and rotting. In an acidic environment with a pH value less than 5, acid-loving fungi such as Phytophthora and southern blight are prone to multiplying and causing disease. Once you understand the harm caused by potting media and water being too alkaline or too acidic, you will pay attention to regularly measuring the pH value of the substrate (preferably once every 3~6 months), and when it does not meet the requirements, correct the deviation promptly, so that the orchid plant has a suitable environment for growth. For potting media, special orchid potting media should be used, such as Zhijinshi, Xiantu, peat soil, red brick granules (from the south), and so on, all of which can meet the requirements. For orchid watering water, the south has more rain, and the water used can all meet the requirements, avoiding the harm of acid rain. In the north, where there is little rain, orchid growers mostly use tap water (mostly groundwater) to water orchids, and tap water quality is mostly alkaline, so the water needs to be treated. An appropriate amount of edible vinegar, hydrochloric acid, acetic acid, monopotassium (sodium) phosphate, or citric acid, etc. can be mixed into water that has already been left to stand until it meets the requirements, and then used for watering. This can also regulate the pH of the potting media. I often use citric acid to treat pH value, and the effect is very good. Of course, using rainwater is best! If the pH value is less than 5, alkaline substances such as sodium bicarbonate and lime can be added to adjust it until it meets the requirements. (jjh)