Plant physiology is part of the curriculum in almost every school across the country.  In the junior grades, delighted children will often grow a pea or bean plant from seed in a Styrofoam cup.  The sense of accomplishment that comes with hands-on nurturing inspires kids and creates a desire to learn more.  They eagerly ask questions and absorb information like little sponges.

In middle school kids often use plants and growing methods as part of their science fair projects.  They will carefully construct a healthy, viable growing environment where plants can be expected to do well.  Alternatively they will provide an environment that is less than favourable for growth, the results being carefully monitored and documented.  This provides kids with important knowledge about environmental influences on plant growth and gives them the foundations for building a scientific hypothesis.  

By high school kids are usually presented with text book learning.  Read and memorize paragraph after boring paragraph of facts about a plant's reproductive cycle or the names of the various plant parts.  While this method of learning may help kids strengthen their overall learning skills it does nothing to heighten their sense of wonder and curiosity.

It is unfortunate that most of our growing season occurs while kids are out of school for summer holidays.  During the school year it is difficult to study a plant's cycle from germination to harvest in a natural environment. 

Many schools have opted for hydroponics to demonstrate plant growth.  A hydroponic garden can easily be maintained year-round  in a limited space making it well suited for most classrooms.  Artificial light can be added to supplement existing sunlight supplied through a window or can be used completely on it's own where no light is available.

Hydroponics is new and exciting to students.  They are challenged by the prospect of growing without soil.  The strange variety of growing media intrigue students, encouraging them to learn more.  Plants can be anchored in commercially produced media like the small pea like rocks known as Leca, made from heated clay or rockwool, a fiberous  spun rock substance that resembles insulation.  Or students can experiment with various media such as sand, corks, pebbles or marbles.  An ideal growing medium should be sterile, pH neutral with good water and air retention properties.   

The growth influencing factors for plant growth are the same in hydroponics as they are in soil. Light, air, water, nutrients, heat, carbon dioxide (C0₂) and a growing medium are all essential for growth, however indoors the grower provides all these life sustaining forces.  

Simple systems seem to work best when introducing hydroponics to the classroom.  Passive or deep water culture systems are completely self contained gardens that require minimal maintenance and are available in single or multi plant containers.  Plants in mesh pots are suspended over a reservoir of nutrient solution that is aerated with a small aquarium pump.  This system is excellent for demonstrations as the strong and healthy root growth is easily viewed.  Hydroponically grown plants spend less energy searching for nutrients therefore they are stronger and grow faster than their soil grown counterparts. As kids learn more they can be introduced to more complex hydroponic systems and experiment with the growth influencing factors.

Essential nutrients can be purchased from hydroponics retailers as individual components and trace elements.  This gives students the opportunity to play with different mineral ratios and learn what effect a deficiency or surplus of a specified element will cause.  There are pre-mixed formulas on the market that are very easy to use and provide complete nutritional balance.   

pH must be monitored and maintained at an acceptable level of (5.8 - 6.3 for most plants)  for proper growth.  This is always fun and interesting for students as the results vary with seemingly small pH fluctuations.  Experiments can be performed using solutions that are acidic, basic or neutral.  pH can easily and inexpensively be monitored  with litmus paper or pH test solution.   

Our atmosphere usually contains sufficient  carbon dioxide (C0₂) for adequate plant growth.  It is interesting to note what happens when plants are deprived of C0₂.  Conversely, plants are able to process more C0₂ than they are exposed to in normal atmospheric conditions.  Baking soda and vinegar produce C0₂ and under careful supervision can be used in C0₂ enrichment experiments. 

Keeping a journal is a helpful resource that allows students to reproduce successful crops and avoid duplicating mistakes.  For the most part a hydroponic garden is self sufficient.   Completely changing the nutrient reservoir every week to ten days will help ensure plants receive optimum nutrient uptake. When this isn't  possible top up the solution with water and adjust nutrients and pH accordingly.  

Teachers typically have time and budget restraints and limited resources.  Many hydroponic retailers offer schools a complementary seminar, set up and ongoing support for their hydroponic systems.  Some of the larger companies will even provide schools with a free system to get them started.  There are inexpensive gardens on the market that come complete with pots, growing medium, nutrients, pump and pH test kit and pH adjusting solution and detailed instructions for individual projects.  

There is a wealth of information on the web; hydroponics.com is a comprehensive site whose mascot, Jack, easily navigates visitors through the site.  There are many books and publications available on hydroponics; visit your local library or your nearest hydroponic retailer.

 Students are anxious to participate and enthusiastic when working in a hands-on environment. Indoor gardening provides kids with the opportunity to learn as they grow. Watching seeds sprout to life, grow and bloom is rewarding and instills a sense of pride and accomplishment.  Teaching kids about the life cycle of a plant is easy when it unfolds in front of their eyes.

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