Why do I have to use a cube?

To maximize the efficiency of substrate use and the control that you have over the root zone of the plant, it is important that the right layout of slabs and cubes are used. The whole concept of the Cultilene stonewool system is to create as even or consistent a root environment as possible to maximize the use of the substrate.

The cubes should be evenly spaced along the length of the substrate so that each plant / dripper has the same volume.

The right dose size and drainage slits are calculated based on the volume of substrate per plant / dripper based on this principle as below. The dripper has grooves down the sides to allow the water to flow down into the substrate.

The flow of this water is spread evenly by the stonewool to refresh the nutrient solution around the roots. This is what we call the Cone. The Cone starts in the cube and spreads down and sideways. The cube will increase the width of the cone and the volume refreshed by the dripper giving more efficient water and fertilizer use.

This is vital in giving good refreshment and even water content, EC control and minimizing drain. The cube is also important in keeping the base of the plant dry. This is important for preventing basal disease issues.

The height of a stonewool substrate has a big influence on the water content. The higher the column of stonewool the bigger the difference in the water content from top to bottom. So using a cube will raise the column and keep the top of the cube dry.

Slab height = 75 mm
Cube height = 65 mm
Total column height = 140 mm
 

No cube used

If the plant or plug is placed directly into the slab, then the dripper also has to put directly into the slab. This gives many potential issues.

• Poorer Cone: the water from the dripper will not spread sideways as far giving a narrower cone and more variation in the water content and EC down the length of the slab. This will give less efficient water use and potentially more drain unless much smaller dose sizes are used.

• More Disease Risk: the column of stonewool is less so the base of the plant will be in a much wetter areas and so much more prone to root problems, basal rots and diseases. Slab = 75 mm height, no cube, Total column height = 75 mm. Problems usually gradually start with Pythium and Phytophthora. This will increase the need for chemical use.

• Smaller Plants: using a cube means that a larger plant can be produced during the propagation phase than a plant produced in a small plug to be directly planted into the slab. This gives many advantages:
  • the plant can be held longer in the propagation area so production of the previous crop in the glasshouse can go on longer;
  • the plants will be put out into the final position when they are older which will give a more even plant selection;
  • spare plants can be held for longer to replace lost plants in the glasshouse;
  • for some crops (tomatoes, capsicums) holding the plant in the cube is a vital to control the balance of the plant and to steer it in a generative way using water content. Placing a small plant in a plug directly into a fully saturated slab in a very vegetative action;
  • if the plant becomes vegetative yields will suffer and more energy will be needed to control the growth.

The Cultilene system using plugs, cubes and slabs is well tried and tested over 30 years.

If you need more information on the set-up and use of our stonewool systems, please contact us.