Hydroponics and Hydroculture

By Joelle Steele

To some of us, growing a plant without good old-fashioned “dirt” seems unnatural. We’re so accustomed to seeing plants growing in soil that we assume they cannot grow properly without it. But plants do not require soil. In fact, plants grown in water alone (hydroculture) or in hydroponic systems (containers or units filled with water and such non-soil media as crushed rock or vermiculite) are often healthier than their soil-grown counterparts.

Hydroponics offers many benefits to gardeners. The sterile medium eliminates soil-borne pests and diseases as well as weeds, drastically reducing the need for toxic chemical controls. Lack of humidity is no longer a concern as the water supply provides atmospheric moisture. Hydroponic gardening takes the guesswork out of watering and fertilization. Exact amounts of nutrients are given at specific intervals, and the plants use them as needed. Nothing is leached out of the root system, the roots do not grow as extensively in water as in soil and the plants make at least 20 percent more crown growth. They also take up less room and can be grown in individual pots and containers of whatever size, shape or configuration the available space dictates.

For beginners, basic hydroculture or water culture is an inexpensive introduction to this gardening method. One or two plants (of the same or different species) are dis-played in containers filled with water and nutrient solutions. More advanced hydroponic systems may contain supportive materials such as charcoal and gravel.

CONTAINERS

For true water culture, almost any heavyweight, clear glass container of any shape or configuration may be used. For plants that require more support than water alone can provide, a layer of crushed rock in the bottom of the container will give the roots a foothold. Charcoal from your aquarium supplier can be used and has the added advantage of deterring the growth of algae, a harmless but unsightly green growth that sometimes covers the inside of the glass container, particularly if it is in a warm, sunny window.

Containers and any support media must be thoroughly sterilized before you introduce plants and water. Scrubbing with hot soapy water should do the trick. If you decide to grow a mature plant in water rather than rooting a cutting, you must also remove all traces of soil from the plant. Then place it into the container and slowly pour the water around the roots until part of the stem is underwater. If the leaves get wet in the process, be sure to blot them dry with a soft cotton towel.

WATER QUALITY

Because the purity of the water is important, it must be replaced at least once every four weeks. If algae form between changes, the container must be scrubbed out and all traces of the algae must be removed before the water is replaced. To help cut down on algae, reduce the amount of fertilizer you use. And, whenever the water level drops between monthly changings, add a little more water.

Water pH is also important. To measure the pH of the water, you will need a pH testing kit consisting of nitrazine paper strips. Check the water weekly. A pH reading between 6 and 7 is ideal. When the pH is not within these limits, the plant may not be able to use the available nutrients. If the water is too alkaline, (over 7), neutralize it by adding drops of vinegar or grains of aspirin, retesting after each drop or gram until the proper level is reached. Though it is not common, water that is too acidic (under 6) can be neutralized by adding bicarbonate of soda.

Chlorinated water affects pH levels, so let the water stand for 48 hours until this chemical dissipates before filling your containers. Never use artificially softened water. And if you decide to use a hydroponic system that collects drained-off water and nutrient solution, it should be reused only for a short period of time — three to four days at most.

NUTRITION

With hydroponic systems, almost any plant food can be used as long as it is water soluble. In addition, the manufacturer’s package should state that it is a "complete fertilizer” specifically formulated for the types of plants you are growing. Reduce the ES amount recommended by about one third for use in hydroponic and hydroculture systems. The only time to fertilize is each time the water is changed. Fertilizers specifically formulated for hydroculture are available.

GROOMING

Plants grown in hydroponic systems do not require a lot of care, but they do get dusty and should be cleaned regularly so their pores do not become clogged. Remove any dead leaves from the plant or the surface of the media. Those dead leaves can decay and “pollute” your otherwise sterile system.

DIFFERENT METHODS

A variety of hydroculture and hydroponic methods are readily available in the United States:

Continuous Flow Method: Involves three containers arranged at different levels with the highest containing nutrient solution with a tube leading to the middle com tamer where the plant is located. Another piece of tubing runs from the bottom of the middle container to the lowest container. As the top container empties, it is refilled from the bottom one, recycling the water and nutrients. This is a workable system but may not be practical as it also requires aerating the solution with oxygen.

Gericke Method: Uses waterproof troughs topped by a wire grid with a mixture of peat and hay (or sawdust). The plants are stabilized in the media so their roots grow through the grid and into the nutrient solution below with a space for oxygen left between the grid and the liquid. Other methods use traditional pots filled with substances other than soil.

Sand Culture: Consists of a pot filled with sand and water. But the sand usually becomes waterlogged unless it’s mixed with gravel for improved drainage.

Aggregate Culture: Employs gravel, perlite, vermiculite and wood chips. Gravel or vermiculite is used in combination with sand for water retention, and the amount of sand used is determined by the frequency of watering. The less often you want to water, the more sand you use. This method requires some experimentation to discover the right combination of materials.

Flower Pot Hydroponic System: Relies on a variety of watering methods. Those systems in which water is passed through a growing medium and into a drainage reservoir are called "active" and those that rely on wicks or sub-irrigation are termed "passive."

Automated Sub-irrigation or Wicks: Operates by means of capillary action to draw moisture to the root system from a reservoir.

The Gravity Feed: Consists of a bucket reservoir that feeds nutrients directly to the aggregate via a hose.

Slop Method: This method has a pump that floods the surface of the medium with water, which seeps into the root system and exits through a drain into a container from which water and nutrient solution can be reused for a short time.

It takes some experimentation to determine which system you want to use. Budget is certainly one consideration, as are available space and the quantity and kinds of plants you want to grow.