Water temperature for your plants
When watering your plants, it is essential to use water at the right temperature. This is because the roots of your plants are very sensitive to extremes of temperature. Using water that is too hot or too cold can put your plant under stress and cause damage.
The optimum temperature for roots to absorb water and nutrients is around 20°C. At that temperature, the water in the substrate still contains a lot of oxygen, and it is also exactly the right temperature to trigger the pump mechanism in the roots. At lower temperatures, the pump mechanism will not work as effectively, while at higher temperatures the plant is less able to take up oxygen from the water. Additionally, higher temperatures and a lack of oxygen can cause an increase in harmful moulds (such as Pythium) and bacteria, and all the problems that associated with those.
So it’s very important to maintain the right temperature in your substrate. Unfortunately, you can’t regulate the temperature of the substrate through watering. To do that, you would need to use extremely hot or cold water, and as we mentioned, that would put the plant under stress; and in any case, a quarter of an hour later, the temperature in the substrate would be back to what it was before watering.