Hydroponic Living Walls – Precision Growing

Simply put hydroponics is the cultivation of plants in nutrient solution. It is big business and for many crops it has taken over horticulture as the growing method of choice because it is so efficient and predictable.

How plants grow in soil

In naturally sustainable (horizontal) landscapes water transfers nutrient solutes around and soil particles attract and hold these through ionic bonding. The humus content of soil helps buffer pH, and is the end result of the breakdown of compost into humic acids and humins.

The soil is also layered with micro-organisms and mycorrhizae each performing specific functions, all of which add up to an incredibly complex web of self-regulatory systems, which create a stable environment for life. Gravity plays a huge part in the stability of these systems; holding it all together and ensuring the necessary inputs of rainwater and fresh material in the way of falling dead and decaying matter.

It is simply not possible to replicate this naturally occurring environment in a vertical plane.

Vertically Challenged Soil

When compost or soil is stacked vertically there are three fundamental issues:

How plants grow in hydroponics

Hydroponics by-pass all of soil’s complexity, whilst avoiding the problems of using compost as the growing medium. In soil, a plant might expend 60% of its energy in searching for food, whilst hydroponic plants have everything delivered to them.

Hydroponic mediums have a zero-cation exchange and nutrients are supplied in a precise and controlled manner. This means that far less water is required as an input to a hydroponic system.

Grodan® — the ultimate growing medium for living walls

At Biotecture we carried out extensive research and trialling, working with several horticultural companies, before we selected Grodan® in 2008 as our growing media partners for our patented living wall panel system. It is the perfect material for vertical growing.

Grodan® are part of the Rockwool Group and their mission statement is “to supply innovative and sustainable stone wool growing media solutions to the professional horticultural sector based on precision growing principles”. As a professional horticultural company ourselves we understand that the vitality and longevity of our living walls depends on precision growing principles.

Grodan® has been awarded a European Ecolabel for sustainability and as a material it is:

Grodan® v. soil for living walls

The above three factors mean that Grodan® is the most robust, resilient and precise growing medium available for use in living walls. It will:

  • Withstand wind better than soil
  • Outlast soil by decades
  • Continually offer a more predictable root zone for the plants than soil
  • Not lock-on to nutrients with age thereby offering a full suite of nutrients to the plants throughout their life unlike soil
  • Grow longer lasting more resilient plants than if grown in soil
  • Require far less water than soil throughout the year
  • Demonstrate far greater resilience than soil in an outage because of its incredible (and predictable) water retentive quality – because of this our living walls will last more than 2 weeks without irrigation if necessary

Simply put: if the goal is to achieve a long lasting, resilient, low water use living wall with healthy plants then there are no valid reasons that we can think of for choosing soil over Grodan® as the growing medium in such a technically, horticulturally and hydraulically challenging environment.