Growing orchids in semi-hydroponic. The second part.

Substrate.

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One of the most important elements of the system. Here are properties that should have a substrate:
He must be neutral, not from organic materials, have good capillary, is resistant to salt solutions and a weak acid, reusability, regular form.
Consider separately.
Neutrality, not from organic materials, resistance – it is clear that the substrate should not give anything in the pre-planned solution.
Capillary action – the basic property of the substrate. On it, in fact, the whole method is based. The solution of capillaries in the substrate rises to the plant by creating a breeding ground around the roots of plants.
Capillarity substrate can check the following way. In the test tube with a diameter equal to the average particle diameter of the substrate, pour a little water. Laying substrate vertical columns. Particle to particle. Note the time when the upper particle of the substrate becomes wet. The sooner this happens – the better substrate.
Reusability do not need extra explanation – it’s clear. The only thing that should add – the substrate must be resistant to high temperature – for roasting. Since roasting is simply necessary for disinfection and cleaning of the substrate.
Here you should read the article about the preparation of the substrate.
Let us talk about regular form of the substrate or on the packaging substrate in more detail.

Substrate packaging.

Packaging substrate effect on the ratio of air, solution and mass of the substrate in the tank. A proper ratio of air and water is no less important for orchids than the temperature, light and water.
Consider how they live orchids in nature. No, not all orchids – it is not possible in the article, but those that we usually grow. This is typically tropical epiphytes. Say cattleya.
So, our cattleya hangs on a tree. Where else, in the fork of branches. Rain it pours in the rainy season, fog in the morning, the humidity 70 percent. Food is brought from the water in small quantities. Somewhere drop passed through bird droppings, but the rain clouds, the dust from the air collected so brought, that’s all. Organic edible on the tree there. Do not chew on same crust?
Cattleya adapted. Roots clothed in velamen – spongy tissue that could absorb the water. Bulbs, as reservoirs of food stocks. But the rain has passed, the wind blew, the sun warmed and dried up all around.
This brief. More information can be read in any book on orchids.
What have we learned? The fact that the majority of tropical orchids in need of a damp but not wet, fast and well-ventilated and air environment.
Now armed with this knowledge back to the substrate, and now it is clear that the ratio of air, solution and mass of the substrate in the tank plays a primary role in creating good conditions for tropical epiphytes.
In short, should be damp but not wet around the roots. And the air.
Now about the package. Generally speaking it is the whole engineering science. And the mathematical field dealing with problems like “What is the maximum number of squares can be inscribed in a circle, to make maximum use of space”.
Suppose that our substrate is composed of cubes. From the standpoint of capillarity – perfectly. Most wettable surface, dense application of faces to one another. But the air in such a system would not completely. This is bad.
The best form for the substrate – the ball. And a lot of air to and from the fact that the balls of different diameters, they stand little between large and wettable surface is very extensive.
To obtain such an effect, when planting, it is necessary to shake the pot, and not push the substrate, as when landing in the ground.
And as the material for the substrate, you can use expanded clay, especially if it is run-in, but best Hydroton expanded clay pellets.
Thus, in practice, achieve the desired package.
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When planting in the usual substrate, its loose and trying to leave the air. But not so in the semi-hydra. In the semi-hydro, we do not loose, we are sealing, shaking. As if filling cans sugar.
After filling, look carefully at how settled substrate. Cavity is unacceptable. Everything must be packed very tightly, otherwise there will be irregularities in the capillary suction of the solution.
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Such cavity circled in red.
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To fix cavities easily tapping on the walls of the vessel, seeking corrections.
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