A Child’s Hydroponic Garden

Hydroponics can be a fantastic tool to teach children about plants, and as a biproduct, the environment, technology, discipline and survival skills. Children as young as six-years-old can really enjoy the experience of growing plants without soil.

A garden can be set up from “found objects”, old quart pop bottles, half gallon plastic milk jugs, even old tires. The small gardens created from several found objects can grow vegetables in the growing season. They can also be set up in a greenhouse or sunroom for year round growing.

These simple gardens will have to be hand watered with nutrient water once a day, so the project can teach responsibility and performing tasks regularly.

Growing Containers

An ideal hydroponic growing container is something that is both waterproof and does not let light into the interior. If clear bottles are used they can be wrapped in aluminum foil to prevent light from reaching the roots.

Using a clear quart pop bottle as an example, the top can be cut off leaving a flat surface. There should be at least four inches of space from the top of the bottle cut and the bottom of the bottle.

Each hydroponic grower needs to have a hole cut about an inch from the bottom to act as a drain hole to drain any excess water. This is especially important for children who do not yet have a sense of dimension and will tend to overwater. When the drainhole exists the excess water will drain out and the plant will not die from excess water.

A drain hole of about 3/8 inch can be cut in the bottle with either an exacto knife or a drill. Then a 3/8 inch plastic tube can be inserted in the hole to drain the water away from the grower. This plastic can fit snug and if not, it can be fastened with either bathroom caulking or a hot glue gun.

Many things can be used as hydroponic growers: plastic tubs, milk bottles, or plastic crates with plastic lining. In each case a drainhole should be cut an inch from the bottom and there should be three to four inches of space above that for the growing media.

Growing Media

Hydroponic growing media can be several different materials. Peat moss and other moss can be used, also volcanic materials such as pumice or lava. However, one of the easiest and most foolproof is perlite. Perlite is normally available at garden centers or the garden area of the large home stores. It is especially good for a child’s garden because it will not charge pH and it wicks water up to the surface of the grower. This means that small seeds should have enough moisture to germinate in the top of the grower.

Putting perlite into the growing container can be dusty, so it is important to wear a dust mask when handling the dry media. Another solution is to wet the perlite before pouring it from the bag. Using a dust mask and having the child wear one is a good lesson in safety when working on technical projects.

Throughout the process of building growing containers and filling with growing media, the child may have questions and could be thinking of other things that could be used. If possible praise any ideas the child may have and then if it can be done, include an experiment to try that idea. The most important part of learning in hydroponic gardening will be finding out what does not work and why.

Setting Up The Garden

Once the containers are built and filled with perlite they can be set up in the garden area. This should be an area that gets plenty of light, and is sheltered from heavy winds or rains. A corner of the house will probably not work unless it gets plenty of light.

For a hydroponic grower to be successful, the media should be wetted with nutrient water, but not flooded. So each container should have at least three inches of growing media above the drain hole and probably not more than six inches.

The drain holes are going to drain out any excess water so it is important to place each grower so the excess nutrient water is either collected below or allowed to drain away. By catching the excess nutrient water and using it the next day the child can begin to learn about conservation and recycling, two important environmental principles.

Once the garden is set up seeds can be planted or small seedlings can be purchased and repotted into the growers. Before either are started it is important to wet down the growing media with nutrient water

Nutrient Water

For a beginner, it is important to get a real well designed hydroponic nutrient. These can be obtained from a nearby hydroponic store or an online supplier.

There are many hydroponic nutrients on the market and most work very well. These nutrients are more complex formulas than common commercial fertilizers. The primary differences are that the hydroponic nutrient contains all the trace minerals that are required by plants and that the nutrients are balanced. Balanced means that the nutrients are in proportions equal to what the plant will take up during growth, and nutrient water will not change pH as the plant selects what it needs.

The nutrient water should be mixed in a separate water container. Tap water or well water can be used. Distilled water or rainwater can also be used and are probably best because they have few nutrients in the water. If well water is used it may have excess minerals that will conflict with the hydroponic nutrient water or add so many salty ions that nutrient water becomes too rich for the plants.

The nutrients should be mixed in a plastic container that does not let light into the interior. If light gets in then algae will start to grow. When the nutrient water is mixed check to see that there is no white solid that froms in the bottom of the container. This solid means that some of the nutrients have combined into a solid and are now no longer available for the plant.

If a solid forms, this can be prevented by mixing nutrient in warmer water or allowing parts (if it is a two part nutrient) to have time to dissolve before adding the second nutrient.

Planting Seeds or Seedlings

It is good to try both store bought seedlings and planting seeds in the growers. The seedlings offer a faster result and allow the child to learn about hand watering. If a watering is missed, or several, the plant should suffer and the child will start to learn.

Seedlings coming from the store are usually planted in a growing media that contains some soil. When transplanting small plants, carefully remove each one from the container, taking care not to injure either the roots or the young plant. Put the roots in a container of nutrient water to wash the roots and wet them.

Push some media aside to go deep enough to give roots space to go down. Place the seedling in the hole and push media back around the plant. Give seedlings in the grower enough surface space to grow into good sized plants. Hydroponic plants can grow to be very large compared to plants in soil.

Seeds are planted in hydroponic media the same as in soil, usually planted from one half to an inch below the surface. Very small seeds can fall though the growing media especially if the watering is done without great care, so you might want to start with seeds that tend to stay put such as pumpkin seeds or beans. Stay away from small seeds that require longer germination times such as mint and mint like herbs.

Some seeds like tomato and bell pepper may take longer to germinate. While beans should be showing up through the growing media in five days, some tomatoes and bell peppers may take two weeks. The tomato seedlings are also very fragile and can easily be broken by an inexperienced watering.

If nothing shows through the media in the expected germination time, push back the growing media and see if you can discover what has happened to the seeds. Some will be missing, lost in the media, some will be rotted, experiencing too much water and not enough air, and some will be still ungerminated. All of these failures are important lessons in learning about hydroponics.

Growing Plants

Vine beans are some of the most interesting plants to grow. If several are planted a few can be dug up each day to show the germination process. The roots start first and orient downwards towards the water. Then the shoot starts to push up through the media. Beans will then follow the source of light. They may quickly grow across the room if they sense light is sufficient or better somewhere else.

Care for the Garden

As the hydroponic garden grows, there can be problems of insect attack or disease. This is a new learning experience, how to recognize the different insects and then how to get rid of them. A dish soap is a good repellent for most insects, or a spray with vegetable oil. A spray of garlic water can prevent insects.

If the child’s garden can continue to grow and produce food it is very rewarding for the child. Having resulting vegetables is probably not as imporatant as all the learning experiences along the way, but it is a part of the process.

When the child has had some success with hydroponic gardening they can continue the process by trying new vegetables, bigger growing containers, or experimenting with other growing media or nutrients. An organic hydroponic nutrient can be mixed from the black soils of a worm farm.