Hydroculture

Principle

You see it all on the image on the left: the plant is placed in a double container. The external pot is an earthenware container. The internal plastic envelope has slots to let water through, and is filled with clay bubbles, in which the plant grows. There is no soil.

The roots must be immersed in water, which fills a part of the system. The water level is controlled with a floating gauge. The pots have a water reserve that allow to space watering every four or five weeks.

As a fertilizer, I am using an ion exchange resin loaded with inorganic nutrients: nitrate, phosphate, potassium, magnesium, ammonium, and oligo-elements, principally zinc and iron. Liquid fertilizers can also be used, but the advantage of ion exchange resins is that they allow the nutrients to diffuse in the water according to the needs of the plants, so any overdose is avoided. One cartridge or pouch of ion exchange fertilizer lasts several months (4 to 8 months depending on plant size).

Growing according to this system is particularly useful for indoor plants. Take a "normal" plant, carefully detach the root ball and rinse it until the roots are bare, then transplant it into the clay beads. The plant's acclimatisation time to its new soilless environment varies between three and six weeks, during which it is better not to touch it too much.

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History

I started hydroculture in 1979 as the company for which I was working developed the ion exchange resin mixture suitable for this application. Since then, I planted:

• ficus of various sorts,
• dracaenae,
• crotons,
• a caphorbia*,
• an aloe vera,
• a beaucarnea (called elephant foot),
• and a few other plants of which I forgot the names.

The ficus are particularly suitable for hydroculture. From a cutting, I managed to produce a tree that grew to 1.6 m high, but eventually died, about twenty years later, due to a watering failure.

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Examples (clic to enlarge the picture and get all details)

Evolution of a ficus benjamina variegata:

Groups of hydroponic plants:

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* Caphorbia: I have probably misnamed the plant. Caphorbia doesn't seem to exist. The plant I have grown belongs almost certainly to euphorbiaceae. It could be one of the three following species:

• Tree spinach, cnidoscolus aconitifolius, also called chaya.
• Fatsia japonica (faux-ricin, aralia).
• Jatropha curcas.

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