Hydroponic growing with rock wool or coconut fiber-Best with probes

We are going to dedicate this article to hydroponic cultivation with rock wool or coconut fiber and the importance of controlling it by sensors / humidity, temperature and conductivity probes for irrigation .

What is a rockwool hydroponic culture?

Hydroponic comes from the Greek words hydros (water) and ponos (cultivation). The technique consists in that we do not use soil, but it is convenient that the roots of the plant take root in some way and at this point enter the rock wool .

Rock wool
Rock wool

The rock wool or coconut fiber cubes prepared for sowing or planting must be submerged in water for at least 24 hours and with a controlled pH.

Where are there hydroponic crops?

Hydroponic crops are growing in many countries, including Spain and also Portugal, mainly in hot climates with many sunny days and especially if the soil is not suitable for outdoor cultivation.

Maceta de lana de roca
Maceta de lana de roca

The map above shows roughly those with the most hydroponic greenhouses in the world. In Spain they abound in Andalusia, the Canary Islands and Murcia. Especially in the province of Almería.

The crops that are best suited to hydroponic greenhouses are:

  • Tomatoes.
  • Peppers.
  • Courgettes
  • Melons and watermelons.
  • Cucumbers
  • Strawberries and red fruits, such as blueberries, raspberries and blackberries.
  • Green beans.
  • Lettuce
  • Cabbages and cauliflower.
  • Broccoli.
  • Peas beans and snow peas.
  • Coriander, parsley and other aromatic herbs.
  • As a tree the banana.
  • Ornamental flowers.

The plant is not convenient to sow in rockwool. We must make separate seedbeds and transplant. If we bring it from the greenhouse, it is inserted through the hole that you see in the diagram.

Once the plant is rooted, it is ready to be placed in the rock wool support, which in turn is arranged in trays. In the pot we can place the sensor / probe that will transmit the humidity and temperature information to us.

Partes del soporte hidropónico
1 floor. 2-Controlled irrigation and correct pH. 3-Root system. 4-Planter without plastic embedded in the support. 5-Plastic support that covers the rock wool, immersed in the tray. 6-Wet bulb. 7-Humidity and temperature sensors / probes for hydroponic irrigation. 8-Floor protected with plastic that is usually white or black.

Coconut fiber for hydroponic cultivation

Coconut fiber can also be used and the difference is in the pH control.

The coconut fiber comes from the shredded shredding of the coconut. The plant roots easily because the fiber is quite porous, in addition to having the property of retaining water and the organic substances that are added to it well.

It can be used in various growing cycles because it is quite resistant.

soporte hidropónico

Greenhouse preparation

The factors that influence hydroponic cultivation are:

  • We isolate all the perfectly smoothed ground with a plastic, preferably white because it gives more light.
  • We close the greenhouse ensuring that insects do not enter. It is good to put yellow tapes with insecticide that catches those that can get into the installation.
  • The greenhouse must have a good ventilation system.
  • Place the rock wool panels properly protected and make the holes conveniently to introduce the plant or the pot.
  • Place sensors that measure temperature, humidity, luminosity and pH.
  • Install an irrigation system normally by drip that at the same time feeds the plant with the necessary nutrients.
  • If the amount of irrigation is not controlled, it leads to the need to incorporate a system to reuse the excess water. Otherwise, this excess water is very polluting due to the nutrients it contains.

Different ways of growing hydroponics

Hydroponic crops
Hydroponic crops
Vertical hydroponic crops
Vertical hydroponic crops

Advantages of hydroponic cultivation with rock wool or coconut fiber

Rock wool pots embedded in rock wool panels also offer many advantages:

  • Total control of the water that the plant needs and of the nutrients, avoiding the water stress of the plant. Rock wool retains moisture very well and it should not exceed 80%. This humidity can be controlled with Plantae sensors that send information in real time. The same goes for coconut fiber.
  • Permite la medición del pH, la salinidad, la luminosidad, la temperatura y el oxígeno. Cuanto más controlado esté todo mejor para la cantidad y calidad de la producción. Los sensores de conductividad par controlar la salinidad nos dan información en tiempo real.  Lo mismo los sensores de temperatura.
  • Weeds do not grow.
  • Absence of pests and diseases if there is an exhaustive control of the humidity and temperature factors that we can do with the Plantae sensors. Waterlogging can cause root damage that deteriorates the plant.
  • Sterilization of the facilities is made very easy, usually with steam.
  • The quality and quantity of the crops is much higher.
  • Water and energy are saved.
  • Several harvests a year can be carried out if the climate allows it or the greenhouse is properly conditioned with temperature.
  • The products obtained are much cleaner.
  • Cultivation can be done anywhere: terrains of all kinds, terraces, rocky lands, deserts.
  • In rock wool and coconut fiber, the sensor readings are every 2 minutes since they are micro-irrigated.
Sondas en tomates de cultivo hidropónico
Humidity and temperature probes in hydroponic tomato cultivation in Torres Vedras - Portugal


  • Quite high initial investment.
  • It requires adequate training to handle the constants mentioned above.
  • Major production damage if there is a system failure and it is not controlled in a short period of time.
  • Ways should be found to recycle stone wool once it is disposed of. In some countries it is reused for insulation in construction.
Humidity and temperature probes in hydroponics
Humidity and temperature probes in hydroponics

After carrying out tests and trials with this type of crop throughout the summer, Plantae installs sensors with subsoil temperature in strawberries and tomatoes in Portugal. Precision wireless technology and parameter monitoring controls crop humidity in real time and adapts to the micro-irrigation that must be carried out in these types of crops.

Strawberry greenhouse in Torres Vedras
Strawberry greenhouse in Torres Vedras
Sensores/sonda en invernadero hidropónico
Sensores/sonda en invernadero hidropónico



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