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Physical performance of substrates

February 1, 2023

The performance of substrates is one of the factors that determine the success of your cultivation. To get the best out of your leafy greens, it’s crucial to create an optimal environment for the plant’s roots to develop. Many factors work together to determine if a root zone is suitable. For example, we should take physical characteristics like pore size into account. However, factors like microbial activity within the substrate and buffers for pH and nutrients also play a big role in the happiness of your crop’s roots.

In this first article of our four-part series, we’ll take a deep dive into the physical performance of growing media, and how we determine this performance. First, we’ll go over the basic properties and characteristics that make up a good root environment. Secondly, we’ll have a look at the way we analyze growing sites to learn more about the desired performance of the substrate.

Measuring the performance of substrates

So, how can we determine if the performance of substrate blends matches the needs of a grower? Simply put the performance is determined by various measurable elements, which combined offer the final performance of the solution. Among other things, the following elements need to be taken into account:

  • Water Uptake
  • Porosity (water or air-filled)
  • Hydraulic conductivity
  • Capillarity and drainage (gravity)
  • Container capacity

Soilless growing media & hydroponic systems

The cultivation of leafy greens frequently takes place in highly automated hydroponic systems. This requires a specific type of growing media to be used. The growing media must support the crops and optimize plant growth in a controlled environment.

A valuable asset of a hydroponic growing system (e.g. NFT, DWC) in food production is the optimized usage of water. Therefore, one of the main aspects of the growing media you use should support that as much as possible. With this type of growing method, the inputs are monitored closely and the growing media used should enhance the plant’s uptake and efficient usage of water and nutrients. This means that the soilless substrate creates a framework that interacts with the roots and directs the water and nutrients toward the plant. This way, the substrate enables the root system to develop to its full potential and in a way that the grower wants it to develop, supporting sturdy and resilient plants. This creates added value for the entire production chain because it results in a higher crop value.

Let’s have a look at some properties in more detail.

Water uptake

One of the most important physical features of every growing media solution is its water uptake characteristics. Water uptake is defined as the ability of a substrate blend to absorb water after a dry period.


Sometimes this feature is also referred to as hydraulic conductivity. It describes how well water moves through the pores within the growing media. This property is of immense importance in hydroponic growing, as it predetermines the behavior of soilless growing media in dry and wet circumstances and between irrigation cycles.

Pore-size distribution

This substrate property is one of the most influencing factors when it comes to the air and water ratio within the growing media.  As it affects the percentage of pores that will either be filled with water or with air, it has a direct effect on the drainage properties of the mixture, as well as the percentage of easily available water for the crop.

The smallest pores in growing media are influenced by capillary forces, which makes the water in these pores less available to the plants. In other words, plants need to spend energy on getting water from small substrate pores.

Unique plant performance, based on unique growing sites

When creating the optimal soilless growing media, BVB Substrates focuses strongly on the situation in which the growing media will be used. Of course, we also take the desires and wishes of the grower into account.

By a thorough analysis of the growing conditions and technologies used in the greenhouse, an optimally performing substrate can be composed. Influencing factors like the irrigation methods, the specific crop needs, and the energy inputs in the growing site are analyzed by our experts.

The list below provides a quick overview of the data that our experts collect in order to tailor substrates to fit the needs of a leafy greens grower:

  • Climate zone (Often designing ‘Winter’ and ‘Summer’ solutions)
  • Greenhouse type (height, air volume, climate control, etc)
  • Growing system in use (Floating trays, Gutters, Tables, Chambers, Ebb, and Flood, etc)
  • Irrigation system and water giving specifics (one type or additional irrigation as well, sprinklers, how many zones, misting)
  • Crop (crop type, crop variety)
  • Nutrition program (water quality, Sodium, Bicarbonates, EC levels, Nutrition strategy)
  • Handling equipment (type of bale breakers/shavers, water addition before seeding)
  • Germination chambers/rooms
  • Soil sensor types (calibration based on materials)

By taking all these factors into account when designing growing media and their performance, we not only guarantee growers of a product that will be fit for purpose, but we also help growers optimize their growing conditions, resulting in better yield.

Reach out to our team if you would like to learn more about our methods for determining substrate performance and tailoring needs. Keep an eye on our website and LinkedIn page to make sure you don’t miss our next article in this series in which we’ll take a closer look at soilless growing media performance for leafy greens in hydroponic systems.