Debunking Growing Myths: Watering Plants

Caring for plants grown indoors under artificial lighting is equally a science and an art. The key to success lies not only in mastering the basic principles that affect plant metabolism, but also in the experience gained through careful observation. From the questions our customers ask us, we have selected the most common ones that we encounter when they water their plants. Let us present the three most common myths about watering plants and explain how things really are.

Watering plants may seem like a simple task, but it is surrounded by many myths that can confuse both beginners and more experienced growers. The following three misconceptions are among the most widespread, and we encounter them most often among our customers. We know that no one is born learned, and in the following lines we will examine each of these common misconceptions about watering in detail.

Myth 1 – Plants need the same amount of water all the time

Many growers believe that once they manage to establish the “right” watering regime, they can leave the rest of the work to an automatic irrigation system or a less experienced friend. However, they do not realise that plants’ water consumption changes according to the species, growth stage, environmental conditions, and the type of soil or growing medium.

• Plant species and growth stage: Different species of plants grown indoors can have diametrically different water requirements, based on their natural environment. Succulents and cacti require low air humidity and less frequent watering than, for example, tropical plants that are adapted to a permanently moist environment. The growth stage of the plant also plays a crucial role in watering. Young and actively growing plants usually require more water than flowering, slowly growing or overwintered ones.
• Environmental conditions: External environmental factors such as temperature, air humidity or light intensity significantly affect plants’ water consumption. Higher temperatures and stronger lighting cause faster evaporation and transpiration, and plants require more frequent watering. Conversely, lower temperatures and lower light intensity reduce water consumption. Air humidity also plays a major role. In a dry environment, plants lose water more quickly through evaporation from the leaves (transpiration) and need more frequent watering. In a humid environment, the transpiration process is slower.
• Type of growing medium and retention properties of the substrate: The type of growing substrate and its retention properties fundamentally affect the watering regime. Soil-based horticultural substrates and coco can retain large amounts of water and require less frequent watering. Rockwool, perlite, expanded clay or other hydroponic media need frequent watering and are usually part of automatic irrigation and hydroponic growing systems.

Would you like to learn more about the different types of growing substrates and their properties? Read Guide to Growing Substrates.

Myth 2 – It is best to water plants as often as possible, and the substrate should always be fully saturated with water

The belief that the more plants are watered, the better, leads many growers to overwater their plants constantly. However, waterlogging has a similarly devastating effect on plants as a lack of water. A constantly saturated substrate suffocates the roots, which leads to root rot and the spread of moulds attacking the plants. Adjust the frequency and amount of watering to the type of growing medium and the chosen fertigation method.

• Horticultural growing substrates: Soil mixes retain a relatively high amount of water, and plants do not mind if you let the substrate dry out a little between waterings. The soil should not be bone dry, but only dried out to a depth of about three centimetres. If you grow in smaller pots, you can check the amount of water in the substrate by lifting them. Plants grown in soil usually do not need to be watered daily.
• Coco substrates: Growing substrates made from coconut fibres have, in many respects, better retention properties than soil. They retain not only a large amount of water, but also air, so they protect plants from waterlogging better. When growing in coco, it is important to water plants regularly so that the substrate never dries out completely, because the fibres then lose their ability to retain water.
• Rockwool: Rockwool is a hydroponic substrate made from mineral wool compressed into the form of growing cubes or mats. The main advantage of this medium is its stable retention properties. Rockwool is therefore suitable for hydroponics, growing in flood trays or in drip systems.

Are you unsure when choosing a suitable growing substrate? Read the article Soil or Coco Growing Substrate? Choose the Right One for Your Garden on our blog.

Myth 3 – When watering, it is important not to wet the leaves of the plants

Many growers fear that if they wet the leaves of plants while watering, they may burn them or contribute to the development of moulds and diseases. It is true that persistently wet leaves and constantly high air humidity increase the risk of powdery mildew or botrytis spreading. However, occasional wetting of the leaves is generally not harmful and can even be beneficial. Just as in nature during rain, you can wash dust and pests off the plants with water. If you want to spray the plants with water, follow the rules below.

• Ensure sufficient air circulation in the growing area: When wetting plants with water, it is important to ensure that the leaves dry as quickly as possible. Turn the circulation fans to full power and maintain an even temperature and air humidity in the growing area appropriate to the plants’ growth stage.
• Use clean water or a suitable plant protection product: Most water-soluble fertilisers are not suitable for foliar feeding and should not come into contact with the leaves. Exceptions include some special fertilisers containing nitrogen, which plants can absorb through the leaf surface as well. The water you use to rinse the plants should be clean and lukewarm. You can also use one of the protective products intended for regular and preventive treatment, such as CannaCure, Athena IPW and others.
• Wash the plants in the morning before the lights are switched on: LED grow lights emit very intense light, and water droplets acting like magnifying lenses can burn the leaves. If you need to rinse the plants during the light cycle, first reduce the intensity of the LED panel to the minimum level.

Are you looking for a natural product that will protect your plants while also providing them with nutrients? Try compost teas, which can be used both as a spray and as a watering solution. You can learn more about compost teas in the article on our blog Compost Teas: Microbial Elixirs That Revitalise the Soil in Your Garden.