Watering carnivorous plants
Quality watering of carnivorous plants is one of the key pillars of their successful cultivation. With few exceptions, these plants require soft water. The cleaner the water used, the more satisfied the plants will be.
A great tool for determining water suitability is a water quality tester (TDS meter), which measures the dissolved solids in water. For less sensitive plants, like Nepenthes, water with a TDS of up to 100 is suitable. For more sensitive species, such as Venus flytraps and sundews, water with a TDS of up to 50 is preferable.
Tap water
The most readily available water for most people. Its composition varies greatly depending on the water supplier. The water composition can usually be found on the water supplier’s website.
Water hardness is expressed in units such as mmol/l, °dH, or °F.
| mmol/l | °dH | °F | |
| Very soft water | < 0,7 | < 3,9 | < 7 |
| Soft water | 0,7 – 1,25 | 3,9 – 7 | 7 – 12,5 |
| Moderately hard water | 1,26 – 2,5 | 7,01 – 14 | 12,51 – 25 |
| Hard water | 2,51 – 3,75 | 14,01 – 21 | 25,01 – 37,5 |
| Very hard water | > 3,76 | > 21 | > 37,5 |
Very soft water can be used for all carnivorous plants. Soft water is still usable, but at the upper limit of the hardness range, it is advisable to monitor substrate quality, as mineral deposits may accumulate over time. Moderately hard water is suitable for less sensitive species, such as pitcher plants, but the substrate’s condition should be checked, and repotting might be necessary. Hard and very hard water are no longer usable for watering carnivorous plants.
Rainwater
The softness of rainwater is always reliable. However, caution is necessary with rainwater. In areas with increased smog or pollution, rainwater may contain harmful substances that could be detrimental to plants. Despite this, rainwater is generally suitable for long-term use.
River water
River water is a possible alternative but requires caution. It carries certain risks, such as dissolved fertilizers, especially after rain when they are washed from fields. Sometimes remnants of detergents and other pollutants found outdoors can also be present. Additionally, it’s important to monitor hardness, as not all river water is soft. Testing the water with a TDS meter is advisable to determine its suitability.
Well water
The suitability of well water depends on its composition. Wells often have hard water, so if you don’t know the chemical composition, it’s better to look for another, more suitable source.
Demineralized water
This type of water is one of the best options. It can be prepared using reverse osmosis, connected to the water supply. The water passes through a system of filters, removing the majority of minerals and substances unsuitable for plants.
Distilled water
As a final option, distilled water is absolutely pure, making it a suitable choice for watering plants. It can be considered comparable to demineralized water. The downside is the cost of a barrel, though it’s a more financially sensible solution if you have only a few plants, making it more practical than purchasing a reverse osmosis system.