How to treat water quality when watering rhododendrons
When watering rhododendrons, pay special attention to water quality. It is best to use natural rainwater, because natural rainwater does not contain bleach powder and other chemicals and impurities. Next best are river water and pond water, and then tap water. Tap water is softened water that has undergone purification treatment, and it contains chemical agents such as bleach powder, liquid chlorine, and alum. If this kind of water is used for a long time, the alkalinity in the potting soil will gradually increase, which is not good for the growth of rhododendrons. Therefore, the water quality must be treated before use. The treatment method is to acidify it. For water that is neutral or slightly alkaline, it should be prepared into acidic water. The usual method is to acidify the water with ferrous sulfate (green vitriol) and edible vinegar. If the water is highly alkaline, ferrous sulfate and edible vinegar can be used together, and the specific amounts can be prepared according to the measured pH values of the water, ferrous sulfate, and edible vinegar. A simple method is to water for a long time with an aqueous solution containing 0.1%-0.5% ferrous sulfate, or sprinkle a small amount of ferrous sulfate on the soil surface every 10-15 days. It can also be watered once every 10-15 days with an aqueous solution containing 0.5%-1% edible vinegar. For watering, tap water and well water that have been left to stand can also be used. Letting the water stand can reduce the harm of harmful ions in tap water; it can also raise the water temperature of well water and eliminate the temperature difference between the water and the potting soil, which helps root absorption. When using tap water, also add 0.15% ferrous sulfate. If watering can be alternated with decomposed fertilizer liquid water, it is even more beneficial. This is because the regular use of these two kinds of water can keep the potting soil at a certain acidity and also supply certain nutrients, which suits the growth needs of rhododendrons.