La irrigation water temperature It is one of the most determining factors for the success and health of any crop, whether indoors, outdoors, in a vegetable orchard, garden, pots, or hydroponic systems. This often overlooked parameter has immediate and long-term effects on root development, nutrient absorption, and disease prevention. Understanding its importance, knowing its optimal range, and knowing how to control it can mean the difference between a vigorous and healthy harvest or plants that fail to fully develop. Below, we offer the definitive guide to irrigation water temperature, integrating the most comprehensive and practical aspects of the sector's most prominent references.
Why is irrigation water temperature so important?
Water is much more than a simple solvent for plant nutrients. Its function goes beyond simply providing water; Water temperature reveals its role in plant physiology, especially in the radical zone:
- regulates the absorption of nutrients and minerals.
- Determine the amount of dissolved oxygen in the irrigation solution.
- It influences the microbial activity of the substrate or hydroponic environment.
- It affects resistance to root diseases and the availability of certain essential elements.
Irrigating with water outside the ideal range can cause nutrient blockages, slow growth, and cause conditions such as water stress, deficiencies, or the growth of pathogenic fungi and bacteria.
Optimal Irrigation Water Temperature Range
Most crops, whether grown in substrate or soilless systems (hydroponics or aeroponics), have similar requirements regarding irrigation water temperature:
- General optimal zone: Between 18ºC and 23ºC.
- Tropical crops: They can tolerate the upper end of the range (up to 25ºC or slightly higher).
- Winter and root crops: They prefer the lower end (around 16-18ºC).
- Hydroponics: Keep between 18ºC and 22ºC maximizes oxygenation and absorption.
- Rooting and germination: Slightly warmer water (20-22ºC) can speed up the process, but without exceeding the recommended range.
Exceeding temperatures above 23-24°C reduces dissolved oxygen and increases the risk of pathogens; falling below 16°C can block the absorption of elements like phosphorus, causing visible symptoms on leaves and stems.
Impact of Extreme Temperatures: Too Cold or Too Hot
Problems of watering with cold water (below 16ºC)
- Low enzymatic activity in the roots: slows down metabolism and root development.
- Blockage in the absorption of nutrients, especially match and other macros.
- Leaves and stems with purple or blue hues, a typical symptom of phosphorus deficiency.
- increased risk of water stress and slowing of vegetative and floral growth.
- In extreme cases, death of seedlings or seeds due to heat shock.
In hydroponic systems, the negative effect is even more pronounced, since the roots are in direct contact with the solution and there is no substrate to buffer sudden temperature changes.
Consequences of watering with hot water (above 23-25ºC)
- Drastic decline in the dissolved oxygen, essential for root respiration.
- Difficulty assimilating nutrients; fertilizers are wasted, and the plant appears stagnant.
- Frequent appearance of fungi and bacteria pathogens in the root environment.
- Acceleration of putrefaction processes in the substrate.
- Small buds and fruits, poor harvests and, in severe cases, death of the plant.
It is a common mistake in summer, when water tanks or hoses are exposed to the sun or intense heat sources.
How to Correctly Measure Irrigation Water Temperature?
- Digital thermometers: Submersible models offer fast and reliable measurements.
- Combined thermometers (pH/EC/temperature): Ideal for hydroponic systems or professional crops, controlling all parameters at once.
- Thermohygrometers: Some also include a probe to measure ambient humidity and temperature, which helps interpret the results.
It is advisable to always measure in the irrigation tank just before applying water to the plants, since transport or storage can vary the initial temperature.
How to Maintain or Modify Irrigation Water Temperature?
Solutions to cold water:
- Using Aquarium Heaters: Ideal for small and medium-sized tanks. Easy to regulate and safe thanks to their thermostat.
- Thermal mats: Placed under the tank, they help maintain a stable temperature (especially useful in winter).
- Storage in protected and closed places: Keeps water away from freezing temperatures or cold currents.
- Prepare the water in advance: Allow to reach room temperature before watering (especially in winter).
Solutions for water that is too hot:
- Electric water coolers: They guarantee an adequate temperature in large facilities or in hot climates.
- Keep tanks in shaded or semi-buried areas: Avoid overheating from the sun or heat sources.
- Add cold water (in small quantities) or ice cubes: A quick option for lowering temperature in emergencies, but not very efficient for large volumes.
- Cover the tanks with reflective plastic: Reduces heat absorption and minimizes evaporation.
Avoid sudden temperature changes in the nutrient solution, as these stress the plants and can cause leaf or flower drop.
Relationship Between Water Temperature and Other Critical Parameters
La irrigation water temperature It does not act in isolation. Its value influences and is influenced by other parameters such as pH, electroconductivity (EC), and oxygen concentration:
- La EC (electroconductivity) can vary with temperature, so many meters offer automatic compensation.
- El pH It can also be altered by changes in temperature, although to a lesser extent than EC.
- Dissolved oxygen: It is maximum at temperate/low temperatures (between 8-10 ppm at 20ºC) and decreases sharply as the temperature rises.
Using meters that combine these parameters facilitates comprehensive crop management.
Adaptations according to the Type of Crop
Land cultivation
The substrate acts as a buffer against sudden changes in the temperature of the water supplied. However, this parameter should not be neglected, especially in small pots or large-scale crops, where variations of more than 5°C can be negatively impactful.
Hydroponic and aeroponic cultivation
The importance of thermal control is paramount, as the roots are directly exposed to water or nutrient mist. Maintaining the optimal temperature range (18°C–22°C) and having control equipment (heaters, coolers, high-precision thermometers) is essential here. For germination or cuttings, use slightly higher temperatures to encourage initial root development, without exceeding limits that could reduce oxygen or promote fungi.
What happens if you can't maintain the ideal irrigation water temperature?
Sometimes, for environmental or technical reasons, it is impossible to guarantee a fixed, perfect temperature. In these cases, measures must be taken to reduce the negative impact:
- Reduce the dose of nutrients: When cooling water is not possible, reducing the concentration of fertilizers prevents blockages and overfeeding problems.
- Increase water aeration: Use of air pumps in the tank to increase dissolved oxygen.
- Avoid watering during the hottest or coldest hours: Take advantage of the early morning or late evening hours to minimize thermal impact.
- Always measure the temperature before each watering to make informed decisions and reduce risks.
Evaporation and Concentration of the Nutrient Solution
El water evaporated by high temperatures This causes the salt concentration in the nutrient solution to skyrocket, creating blockages and jeopardizing root health. It's important to monitor the water level and replenish it frequently, always using water at the appropriate temperature.
Using reflective materials or black and white plastic over the tank helps minimize evaporation and overheating.
Practical Recommendations and Solutions by Season
In winter
- Use heaters, thermal mats and protected tanks.
- Prepare the water in advance so that it reaches room temperature in an enclosed area.
In summer
- Place tanks in the shade, partially bury them, or use water coolers.
- Avoid using hoses that have been exposed to the sun or other heat sources.
Regardless of the time of year, controlling the temperature of nutrients and water at all stages of the crop remains essential.
Tools and Equipment for Precise Water Temperature Control
Today, the market offers a wide range of devices for monitoring and controlling irrigation water temperature:
- Digital submersible thermometers: Accuracy and ease of use.
- Classic analog thermometers: Economical and reliable in small farms.
- Aquarium heaters: They maintain a constant temperature in small and medium-sized tanks.
- Automatic coolers: Essential in large hydroponic systems or warm climates.
- Integrated pH/EC/Temperature Controllers: Ideal for professionals and demanding crops.
- Thermal insulation for tanks: They help maintain thermal stability throughout the year.
Frequently Asked Questions about Irrigation Water Temperature
- Can I use tap water directly without controlling its temperature?
It is not recommended, as tap water can reach extreme temperatures depending on the season, causing absorption problems or root diseases. - What do I do if I only have very cold water in winter?
Let the water sit in a container indoors or use an electric heater to reach the ideal range before watering. - Is it dangerous to water with hot water?
Absolutely. In addition to losing oxygen, it promotes fungi, bacteria, and root system deterioration. - Does water temperature affect pH or EC?
Yes. Digital meters compensate for these effects, but it is always advisable to measure all parameters before using the water.
Master the irrigation water temperature It's a fundamental advance for any gardening and agriculture enthusiast or professional. Implementing measurement and control techniques tailored to each type of crop results in healthier plants, vigorous growth, fewer pests, and, above all, superior harvests that reflect all the effort and knowledge invested in each irrigation.
