Debunking Cultivation Myths: Watering Plants

Care of plants grown indoors under artificial lighting is half science and half art. The key to success is not only mastering the basic principles that influence plant metabolism, but also the experience gained through careful observation. From the questions our customers ask us, we have selected the most common ones we encounter when they water their plants. We present the three most common myths about watering plants and clarify how things really are.

Watering plants may seem like a simple task, but it is surrounded by many myths that can confuse both novice and more experienced growers. The following three misconceptions are among the most widespread and are the ones we encounter most often with our customers. We know that no one is born knowing everything, so in the lines below we will thoroughly examine each of these common watering mistakes.

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

Many growers believe that once they have established the “right” watering routine, they can leave the rest to an automatic irrigation system or a less experienced friend. They do not realize that a plant’s water consumption changes depending on species, growth stage, environmental conditions, and the type of soil or growing substrate.

• Plant species and growth stage: Different species of plants grown indoors can have radically different water requirements based on their natural habitats. Succulents and cacti require low air humidity and less frequent watering than, for example, tropical plants adapted to persistently moist environments. The plant’s growth stage also plays a key role in watering. Young and actively growing plants generally require more water than flowering, slow-growing, or dormant plants.
• Environmental conditions: Water use is significantly affected by external environmental factors such as temperature, air humidity, and light intensity. 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 faster through leaf evaporation (transpiration) and need more frequent watering. In a humid environment transpiration is slower.
• Type of growing medium and substrate retention properties: The type of growing substrate and its retention properties fundamentally influence the watering regime. Garden soil mixes and coco can retain a large amount of water and require less frequent watering. Rockwool, perlite, clay pebbles or other hydroponic media need frequent watering and are usually part of automatic irrigation and hydroponic growing systems.

Want to learn more about different types of growing substrates and their properties? Read the Guide to growing substrates.

Myth 2 – Plants should be watered as often as possible and the substrate should remain fully saturated with water

The belief that the more plants are watered the better leads many growers to keep their plants constantly overwatered. Overwatering, however, has consequences no less devastating than lack of water. A constantly saturated substrate suffocates roots, leading to root rot and the proliferation of molds that attack plants. Adjust the frequency and amount of watering to the type of growing medium and the chosen fertigation method.

• Garden soil substrates: Soil mixes retain a relatively high amount of water and plants tolerate letting the substrate dry out slightly between waterings. The soil should not be bone dry, but only dry to about three centimeters deep. If you grow in smaller pots, you can gauge the amount of water in the substrate by weight. Plants grown in soil usually do not need daily watering.
• Coconut substrates: Growing substrates made from coconut fibers have much better retention properties than soil in many respects. They retain not only a large amount of water but also air, so they better protect plants from overwatering. When growing in coco it is important to water regularly so the substrate never dries out completely, because the fibers will lose their ability to retain water.
• Rockwool: Rockwool is a hydroponic substrate made from mineral wool compressed into growing cubes or slabs. The main advantage of this medium is its consistent retention properties. That is why rockwool is suitable for hydroponics, flood-and-drain systems, or drip systems.

Having trouble choosing the right growing substrate? Read the article on our blog Soil or coco growing substrate? Choose the right one for your garden.

Myth 3 – It is important not to wet plant leaves when watering

Many growers fear that wetting plant leaves during watering can burn them or contribute to the development of molds and diseases. It is true that permanently wet leaves and constantly high air humidity increase the risk of powdery mildew or botrytis. However, occasional wetting of leaves is not generally harmful and can even be beneficial. Just like rain in nature, water can wash dust and pests off plants. If you want to mist your plants, follow these rules.

• Ensure sufficient air circulation in the growing space: When wetting plants with water it is important that the leaves dry as quickly as possible. Turn circulation fans to full power and maintain even temperature and humidity in the growing area appropriate for the plants’ growth stage.
• Use clean water or a suitable protective product: Most water-soluble fertilizers are not suitable for foliar feeding and should not come into contact with the leaves. An exception is some special fertilizers containing nitrogen that plants can absorb through the leaf surface. The water you use to rinse 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.
• Rinse plants in the morning before turning the lights on: LED grow lights emit very intense light and droplets of water acting like magnifying lenses can burn leaves. If you need to rinse plants during the light cycle, first reduce the intensity of the LED panel to the minimum level.

Looking for a natural remedy that will protect your plants and also provide nutrients? Try compost teas, which can be used as a spray or as a watering. Learn more about compost teas in our blog article Compost teas: Microbial elixirs that revive the soils in your garden.