One of the most popular medium for soilless cultivation is undoubtedly the wool: manufactured by dissolving at a temperature of 1600 degrees basalt, limestone and coke in a special furnace, is being marketed in various formats.

Although it is facing relatively recently on the world of gardening, rockwool exists in nature for centuries in areas with volcanic activity, where the magma is swept by strong winds creating long, thin fibers, however, must wait until 1865 because the man decides to produce at the factory for use as insulation in buildings.

It will take another hundred years before, in Denmark, consider the use of mineral wool commercial horticulture on a large scale since then the spread was unstoppable, reaching about Japan, where it is used for growing Rice, the U.S. and Canada.

To understand fully the quality of the substrate is important to understand how it is produced: the molten rock are placed in a cylindrical rotating and being added with a phenol based resin to the potassium hydroxide and other non-separating.
At this point the amalgam being stretched and pressed into sheets, with particular attention to the force exerted, which will determine its density.

The plates are lightweight and easy to handle, and they are shaped in various forms, mainly "slabs" cubes for cuttings and germination of various sizes and assorted grain flakes used as fertilizer.

The fiber direction is important: the vertical fibers are easier to reuse, are more draining, ideal for driving correctly the young roots.
The length and density of fibers in the final product on the speed of rotation during the work and by the force exerted by the press, the composition of the rocks, and the melting temperature.

Rock wool is a material precisely rendered sterile by the high temperatures needed for its manufacture and this has greatly helped its spread.

Of course, this versatile material is still widely used in construction, but it is a product different from that designed for horticulture: in fact it has a different density, and water reacts differently, it is also completely inert and does not interact in any way with nutrients.
It 's really important to use rockwool for gardening, even though the cost may be higher, and never fall back on that insulating buildings, often produced with waste materials, saturated with metals (especially copper and iron) and a composition that inhibit proper aeration of the roots and alter the pH.

Although full of indisputable merits, the wool also has some defect.
If left exposed when covers of algae quickly and is sensitive to infestation by fungi is always good cover rockwool with a layer of expanded clay or plastic, black or otherwise opaque material suitable to protect the surface from light.
Also, handle the dry rockwool can be dangerous and you must wear a mask, gloves and clothing covering as not to risk contact with mineral fibers.

Finally, the saddest note: disposal.
Although it can be reused several times (after cleaning and disinfection between cycles and more) it's time to throw the rock wool, which unfortunately is non-biodegradable.
In Switzerland and Holland, where the consumption of this material in greenhouses is very high, was designed for a controlled disposal law, with collection and storage performed by the staff of specialized firms.
And 'study reuse in terms of recycling in the cement, certainly more fruitful than simple transportation in the inert landfill.

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2. Irrigation on different substrates
3. Substrates: coconut fiber
4. Germination in Rockwool
5. Systems compared

Tags: guides , no soil , cultivation

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