Hydroponics is the growing of plants without using soil as a source of nutrients. There are many different forms of hydroponic systems ranging from simple and cheap sand cultures to complex and expensive Nutrient Flow Technique systems involving electronic monitoring, artificial lighting and automated watering processes in covered farms that are tens of acres in size. All hydroponic systems require a form of nutrients feed to grow and produce crops.
It is very likely that the tomatoes, lettuces, cucumbers, shallots, herbs and other vegetables that you buy from your local supermarket are produced in hydroponic farms.
A very simple and cheap DIY hydroponic setup that you can make at home is a hydroponic sand culture system. This hydroponic setup is sometimes called a static system, a tray system or a go to waste system. It is one of the oldest hydroponic systems and will produce good crop yields.
We are going to focus on a simple setup using a non–metal waterproof container about 25 cm high (Metal containers will react with the nutrients). And for the medium, sand. That is it. No pumps, no pipes, no complex setups.
For the container, leftover white coolite boxes that supermarkets have received their broccoli in are quite suitable. They do need to be sealed inside with a sealant at the bottom to make sure the plant roots won’t grow through any fine cracks. Some commercial farmers use these as well but they will only last about 2 to 3 years out in the sun.
Drill a small hole 6 mm wide into the container about 25 mm up from the inside bottom. This is for excess water drainage so the plants will not be over watered. It also creates a nutrient reservoir for 2 or 3 days without the need for watering. For a neater water outflow insert a small straw section or tube into the hole. Excess nutrients can be collected and reused so there is very little wastage.
Use enough sand to cover 10cm to 20cm high in the container. Use 10cm of sand for smaller plants such as lettuce and up to 20cm for larger plants such as tomatoes. The sand contains no nutrients for the plant, its function is to anchor the roots and to support the plant. The sand must be coarse enough to allow oxygen to reach the roots. Do not use sand with shell grit as this will cause a build-up of calcium ions which will inhibit the plants from absorbing potassium. Coarse river sand is good. Coarse beach sand needs to be rinsed at least four times to remove the salt content.
Medium to coarse size perlite is a better choice but is more expensive. Perlite is very light in weight and is very porous, which increases its water holding capacity.
Add some seeds or seedlings to the container. Just make sure that those vegetables are suitable for growing in your climate and season. Shading may be needed during summer.
If you use seeds, water them with fresh water until they germinate. You then water the young seedlings with a diluted hydroponic solution of about half the concentration of what you would normally use for that type of plant for 2 to 4 weeks.
Seedlings that have been propagated in a potting mix can also be used. Very carefully rinse the roots in water to remove the potting mix before transplanting in your hydroponic setup. Do not allow the roots to dry as this may kill the plant. Avoid transplanting in the middle of a hot sunny day as this will greatly stress the young plant and it may never recover.
The simple system above will allow for the plants to be watered every 2-3 days. However, hot days or larger plants will require daily watering. If your plant is wilting in the sun, you may need to move it out of direct sunlight during the hotter parts of the day. Under hot conditions, using a shade cloth may be more appropriate.
When watering, different plants absorb different nutrients at different rates. For example, a lettuce plant will only need half the concentration of a tomato plant otherwise the leaves may taste bitter. Simply dilute the SurviveN General Purpose Hydroponic solution that you give to your tomatoes, zucchinis, capsicums and eggplants by half when you water your lettuces, herbs, all young seedlings and other leafy plants. To avoid any build-up of excess nutrient salts flush all your plants with fresh water once a month.
Unless you collect rainwater in a tank, town tap water is not suitable when watering your plants right away. It contains chemicals, such as chlorine, that can greatly affect your plant's growth or even kill them. Let the tap water sit for 24hours in a container to allow the chlorine to evaporate out.
Rain is generally not a problem unless it is for more than 2 days. The nutrients are salts and saltwater is heavier than water. The nutrient solution will remain at the bottom of the container while most of the fresh rain water will drain out. The tomato fruit has a tendency to split if it is exposed to too much fresh water. If this hydroponic setup is placed in a greenhouse then you will have greater control over the environmental conditions that can affect your plant's growth.
Any excess nutrients that flow from the drainage hole can be recycled.
Fortunately for home gardeners, a cheap method of finding out why your plant is sick can also be derived by looking at the plant's leaves, flowers and fruit for abnormal growth symptoms. These symptoms can give an indication of what nutrients are lacking or are in excess. These symptoms can also tell you what other problems the plant may be experiencing, such as insufficient light or a fungal attack.
Once you know what is the cause of a plant’s sickness might be, you can then take appropriate steps to restore the plant's health.
Check out the Why Is My Plant Sick? guide for more information.
Even though hydroponic plants are good at fighting off diseases, they still have to fight pests. Even if it's hydroponic, insects and caterpillars can nevertheless find a way into the garden. Pick off and dispose of any bugs you see.
Green algae in the container is not a bad sign but it may form a surface crust which prevents oxygen getting down to the roots.
Other than to make sure you are watering your plants and checking for creepy crawlies, there isn't a lot to worry about.
Just remember, to avoid any build-up of excess nutrient salts, flush all your plants with fresh water once a month.
As your plants grow and get larger, you may want to train them using string or wire. Hanging string from a support above the plants is a great and cheap way to keep your plants upright. The string is tied to the bottom of the plant and the plant is wrapped around the string as it grows.
For the more keen and advanced growers, you may want to regularly check the ph levels and the salinity readings to really get the best out of your plants.