Rooted in Learning: Hydroponics Professional Development for 5th Grade Educators

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Background Information

HYDROPONICS

Hydroponics, in its simplest form, is growing plants by supplying all necessary nutrients in the plants’ water supply rather than through the soil. Growing plants hydroponically helps gardeners and farmers grow more food more rapidly in smaller areas (greenhouses, living rooms, classrooms, and rooftops, for instance) and to produce food in parts of the world where space, good soil, and/or water are limited. Plants, like all living things, have certain requirements that need to be met for them to grow and thrive. These include water, nutrients, light, air, and structural support for the roots. In traditional gardening, plants get root support, nutrients, water, and oxygen from the soil. Hydroponic growers don’t use soil and instead provide water and the right balance of nutrients directly to the plants' roots, enabling the plants to concentrate their energy on producing leaves and fruits rather than forming extensive root systems to search for water and nutrients. Hydroponic growers use a variety of systems to provide water and nutrients. The systems must also provide roots with the oxygen they need and offer a way for the roots to anchor the plants in place. Some systems grow horizontally which are true hydroponics while others grow vertically which are called aeroponics. There are two main types of hydroponic systems: active and passive.

Passive systems

These systems use no energy to move nutrients and water. Passive systems often use a “wicking” material to draw up the liquid nutrients for the roots to access, or they simply suspend the plants in the solution with an air space around some of the root zone.

Active systems

A hydroponic system is active if it relies on some type of energy (usually electricity via a pump) to move the nutrients in and out of the root zone area and to provide aeration. Systems with pumps to aerate the nutrient solution and deliver more oxygen to roots tend to produce healthier plants more quickly than do passive systems. Passive and active systems can either be media-based or rely solely on water. Media-based systems use some kind of material, such as gravel, perlite, or rockwool to support the plants and the roots in the nutrient solution. Water-based systems do not use any medium other than water, so they require a support material such as wire mesh to keep the plants from drowning. These systems rely on regular contact between plant roots and the nutrient solution. Leafy crops like lettuce and herbs tend to do better in water culture than do fruiting crops like tomatoes, cucumbers, or peppers.

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