CANNA SUBSTRA nutrient is specially formulated to provide the best possible results when used in combination with inert substrate. Of all the inert substrates, rock wool is the most commonly used. Rock wool is widely used in Dutch horticulture because, of all the inert substrates, rock wool ensures the rapid development of good root systems and in addition it is easily managed and it also has good supportive properties. Plants grown in rock wool remain upright without extra support.

Besides rock wool there are many other inert substrates. In this section we will discuss some of these, but considering the popularity and suitability of rock wool we will discuss cultivating on rock wool in more detail.

The origins of growing on substrates

Even though the first farmers quickly discovered that plants grew better on the remains of other plants and dung, it was thousands of years before people understood exactly why. Research into plant food began many moons ago, long before our time, but only recently, about 150 years ago researchers found out exactly which substances in the dung actually feed the plants. And as a result of these discoveries, the artificial fertiliser industry was born.

Shortly before the dawn of this era, in the Netherlands Napoleon introduced monoculture, where one crop per field is cultivated. The combination of these new systems increased farming production to new levels. Initially the new developments produced tremendous results, but this success was quickly reversed. No one was familiar with these cultivation methods and they were certainly unaware of the drawbacks. The damage in the cultivation of vegetables was particularly noticeable. Year after year an excess of artificial fertilisers was applied creating problems in the potting mix structure and in the fertility of the ground.

The same crops were grown year in year out in monoculture on the land. In turn the monocultures brought on a multitude of plagues. Potting mixes bound plagues were particularly difficult to counteract. A good solution was required urgently. Growers began placing the crops in separate compartments and cultivating them on growing medium instead of in the open ground, and this was the beginning of growing on substrates.

When CANNA SUBSTRA was introduced in the 1980s serious small scale cultivation became possible on inert media and rock wool in particular. This CANNA SUBSTRA formula has been used successfully worldwide for many years and even though many have attempted to copy the formula, no slabch has yet been developed.

Clay Pebbles

Rock wool and other inert substrates

Clay pebbles are made by forming clay into pellets and then firing these in a hot kiln. This causes the clay to expand and become porous. Clay pebbles are available in various shapes and sizes and with two types of surface; smooth and coarse. They have the advantage that, as long as they are well cleaned, they can be reused for up to five years. The greatest disadvantage of Clay pebbles is that they can absorb almost no moisture, making them unsuitable as a run-to-waste substrate.


Rock wool and other inert substrates

Perlite is a glassy, volcanic rock that is ground and then baked at high temperature. Perlite is also inert, but due to its poor supportive properties it is relatively vulnerable as a growing medium itself.

However, it can be used as a potting mix improver and particularly to increase the air ratio in the potting mix; though, these days there are environmentally friendlier methods for this, such as adding white peat.


Rock wool and other inert substrates

Mapito is a very light medium with limited water retention capacity. This means that the substrate will dry out faster and so it needs to be watered more frequently.

Mapito is a mixture of Polyurethane (PU), rock wool and sometimes coco or even perlite.

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