Preparing your hydroponic garden

Hydroponics is fun. But, as with any successful project, a certain amount of preparation is required.

Experimenting with different plants grown in water or rockwool leads to a new appreciation of the factors required for them to thrive.

The first, and most obvious thing needed is the plant itself, either in the form of seed or a pre-existing plant. Luckily, nearly any plant can be grown hydroponically with the proper care. Tomatoes are a favorite starting plant for those new to hydroponics. They drink up large amounts of water anyway and can grow to enormous size in containers without soil.

Since hydroponics doesn't use soil to support the plant as it grows, some substitute has to be found. Water is the most common medium but it won't support a growing plant against gravity. The hydroponic gardener uses a number of different methods instead.

A small container with proper supports for the stem will do well. Those supports can be as simple as wooden ice cream sticks or plastic straws glued to the container or secured with string. Kits are available, too, that will supply all the structural components the novice hydroponic gardener will need.

The container size will vary depending on intended use, but a good first try will be about 6-12 inches deep and 2-3 feet wide. A smaller container will work with smaller plants or gardens, obviously. But even a single tomato plant will require room to grow, so better to overestimate than start out too small. Transplanting is a more advanced activity that should be reserved for later.

Fill the container with water. Reserve non-aqueous methods such as perlite or rockwool for later, once hydroponics cultivation becomes more familiar. Start with clean water, but it need not be distilled. In fact, plants grow better in water with minerals. But it should be free of organisms. Sterilize or microwave it to be sure.

The water will have to be aerated. Photosynthesis consumes CO2 and gives off O2, but plants grown in water still need to get oxygen from the medium for cellular respiration in the roots. They'll quickly use up any dissolved oxygen, so it has to be added artificially. An aquarium pump and filter will do the job, but one designed specifically for hydroponics is best.

As with most plants, light is essential. There are exceptions, of course - some plants don't need to photosynthesize. Most plants will require 8-10 hours per day of intense light. That's best supplied by natural sunlight. It's possible to substitute, at least to a large degree, with artificial lights. Sodium lamps and other types specially made for hydroponics are available.

Plants need nutrients. A good supply of NPK (Nitrogen, Phosphorus, Potassium) fertilizer with needed trace elements is the ticket. But look for those with the right percentage for growing in a hydroponic setting. Too much nitrogen, for example, can easily burn a plant living in water just as it can soil-grown plants. Pre-mixed solutions are the easiest to work with. Ensure that they contain roughly the following elements or compounds:

Substance Amount
Potassium Phosphate 1 tsp
Potassium Nitrate 4 tsp
Calcium Nitrate 7 tsp
Magnesium Sulfate 4 tsp
Boric Acid 1/2 pint
Manganese Chloride 1/2 pint
Zinc Sulfate 1/2 tsp
Copper Sulfate 1/2 tsp
Iron Sulfate 1/2 pint
  (per 25 gallons of nutrient solution)

Some water sources may already have some of these. Water testing kits will help you ensure you have the right compounds and pH, which should be close to neutral. Be prepared to change the solution about every two weeks.

A means of keeping the water at the right temperature is vital. Most plants don't grow well in continual cold. That's especially true of tomatoes! Unless the climate supplies all the warmth the plant will require, a heating element is essential. A thermometer to measure the temperature will also be needed.

Once you have your plants and the materials to support and care for them, hydroponic gardening is just a little bit of research away.