Difference in root development: lava on the left, perlite on the right.
Organic and inorganic media
Inorganic media remain virtually intact during cultivation. Examples include polyphenol foam, lava, charcoal and rock wool. However, root growth also affects these media through:
– Physical degradation Roots cause the physical breakdown of the substrate. As they grow through the substrate, the original faction reduces in size over time.
– PH influence The pH can affect the structure of different substrates over time.
In addition to the above factors, organic substrates also concern digestion by micro-organisms. Examples are turf and coconut pellets. In Europe, these substrates are not used. The rate of decomposition is highly dependent on humidity. Wet cultivation on organic substrates greatly accelerates decomposition. In many cases, a dense layer forms on the soil within a short time after cultivation, causing the roots to die. The use of inorganic substrates is strongly preferred.
Buffering of self-cut polyphenol foam.
To the left, good polyphenol foam; to the right, the wrong polyphenol foam.
Cultivation on polyphenol foam.
Rock wool
At Anthura, large cut Anthurium plants in the 9 cm pot size have been grown successfully on rock wool, Grodan Growcube 1x1x1 cm, for many years. Rock wool is also one of the best substrates in Anthurium cut flower cultivation, but it is expensive. Usually, cubes of 2x2x2 cm are used. A few years back, lack of product capillarity was the bottleneck. Nowadays this is in good order (if you choose the right supplier) and the substrate also remains sufficiently moist on top, so that the roots can develop well there. If a low pH (<3.0) develops during cultivation, the structure of the rock wool can break down and form a slushy layer.
At the start, the pH is usually above 6.5 and drops to a pH of 4-5 during cultivation, depending on the variety, starting water, irrigation strategy, and pH control.
Rock wool 2x2x2 cm cubes in W-gutter.
Perlite
The original glassy white rock has a density of about 1100 kg/m³. When heated to 850-900°C, it expands to twenty times its original volume. This is because at that temperature it begins to soften (after all, it is a glass) and the water present in the material forms a lot of tiny bubbles. In the process, large pores are formed. The end product is the grey-white perlite grain.
Despite its excellent capillary properties, perlite often remains somewhat dry at the start of cultivation. This is especially the case if only a drip line is used. Choose a coarse-fraction peat.
Perlite in pot.
Full rooting in perlite.
Rinsing of coconut pellets.
Cultivation on coconut pellets.
Charcoal
Charcoal is a lightweight, black carbon residue produced by heating wood at a high temperature to remove all water and volatile components. This process takes place at a very low oxygen level. Of all organic substrates, this material has the longest lifespan. The water absorption capacity can be disappointing, the capillarity is low, and the Anthurium plants will mainly root around the substrate and not through it, as in the case of rock wool or coconut pellets. At the bottom of the bed, the charcoal will settle over time, creating a smothered layer. A lot of attention should be given to the correct distribution of the watering system.
Charcoal.
Perlite is a worldwide favourite
Inorganic substrates are clearly preferred for cut Anthurium cultivation. The cultivation gets its quickest start on rock wool. Nevertheless, in Europe and Canada perlite is by far the favourite growing medium, thanks to its wide availability and reasonable pricing. In China and Brazil, cultivation is mainly on polyphenol foam, in India on coconut pellets, and in Thailand on charcoal and coconut pellets.
Two drippers due to capillarity.
