This course develops a solid grounding in the principles of soilless cultivation of plants.
There are twelve lessons. Each lesson involves the student in set reading and an assignment (written) which is to be submitted to their tutor for comment. Some lessons will also involve other tasks (eg. research, collection of information or practical work).
Basic Chemistry and Plant Nutrition - atoms, elements, nutrient deficiency symptoms.
Nutrient Solutions - calculating formulae, hydroponic nutrition, preparing nutrient solutions.
Types of Systems A - classification of hydroponic systems, ingredients of hydroponic systems, rockwool.
Types of Systems B - what makes up a system, 16 hydroponic ideas, NFT, solution dispensation.
Plant Problems in Hydroponics - pests and diseases, nutritional and environmental problems, water and plant relationships, pH.
How a Plant Grows - growth, nutrient solutions, preparing a solution, mechanisms of nutrient uptake, photosynthesis.
Plant Culture - controlling environmental features, post harvest storage.
Hydroponic Vegetable Production - how to grow vegetables hydroponically.
Hydroponic Cut Flower Production - growing flowers in hydroponics, carnations.
Soil Media vs Nutrient Film - berries, indoor plants, types of media, NFT.
Greenhouse Operation and Management - solar energy applications in horticulture, greenhouse management.
Special Assignment - a report on how to improve your present hydroponic venture, or a report on planning a new hydroponic venture.
What is Hydroponics?
Hydroponics, the word, is derived from two Greek words:
- Hydro... means water
- Ponos ... means to work or labour.
Today the word has been broadened to mean 'All ways of growing plants without the use of soil'.
The 4th International Congress of Soilless Culture defined the different systems of hydroponics as follows:
- Water Culture: Roots of plants submerged in nutrient solution (eg. Nutrient Film Technique or NFT).
- Sand Culture: Roots of plants in solid aggregate composed of particles with a diameter less than 3mm (eg. sand, perlite, plastics and other inâ€‘organic materials).
- Gravel Culture: Roots of plants growing in solid aggregate composed of particles greater than 3 mm diameter (eg. gravel, basalt, scoria, pumice, plastic & other inorganic materials).
- Vermiculaponics: Roots growing in vermiculite or a mixture containing vermiculite.
- Rockwool Culture: Roots of plants growing in rockwool, glasswool or some similar material.
- Hydroculture: Can refer to all forms of hydroponics but more commonly used to refer to growing ornamental or decorative plants inside.
What is involved?
Soil does four main things for the plants which grow in it:
- Provides support (stops the plant falling over or blowing away by providing anchorage for the plant's roots).
- Provides water through the roots.
- Provides air through the roots (Yes; the plant absorbs gas out of the air through it's roots! A plant's roots can starve for air just as much as they can starve for water!).
- Provides nutrients (ie. Food in the form of very simple types of chemicals).
To be successful; hydroponics needs to successfully cater for these FOUR FUNCTIONS, which are usually handled by the soil.
If the roots aren't grown in a hydroponic situation which will enable adequate support for the plant, then a trellis or some other artificial means must be provided to support the plant.
It is essential to maintain a balance between moisture and air content of the root environment. With some plants the air which is dissolved in water might be adequate; but for the majority of plants, total immersion in water will result in air starvation and death. In anything other than water culture (aggregate culture) the ability of the medium to hold moisture and the relationship of this characteristic to their air holding ability is critical.
A medium which drains very easily usually holds water well but might dry out very easily. This type of medium might need watering very frequently. A medium which holds water very well could become waterlogged and plants could suffer a lack of air if watered too often.
As you can see there is a relationship between how often you apply water AND the drainage and water holding characteristics of the medium. Nutrients are fed to the plants in the form of a nutrient solution (ie: chemical fertilizers are dissolved in water). There are many different nutrients which must be included in the solution, all essential to the plant's growth. The relative amounts of each of the nutrients is important. Though there are rough similarities between the amounts of different nutrients which different plants require, to get the best out of plants, different balances of nutrients are needed for different plants at different stages of their growth.
Sounds Complex ... Not Necessarily!
If you want the best out of hydroponics maybe you need to be a chemist....but most people can grow better in hydroponics than in soil without needing to go that far. It is possible to buy standard nutrient mixtures from hydroponic suppliers. These may not be ideal, but they are adequate for most situations.
Depending on the type of system you are operating (and perhaps other factors) you might apply water only in the form of a nutrient solution, or perhaps both as nutrient solution and straight water (eg. Apply nutrient solution once a week then simply water once or twice a week).
Do You Need a Greenhouse?
A greenhouse is only as good as the person who uses it!
Greenhouses can enable you to grow more plants for longer, and harvest better quality produce and more produce; whether flowers, fruit, vegetables or anything else. To do this though you need to have at least a basic understanding of how plants grow in a protected environment.
They are useful for hydroponics, because they prevent rain from diluting nutrients in the system; but beyond that, the reasons for growing hydroponically in a greenhouse are no different than using a greenhouse for any other way of growing.
Greenhouses are Tools
The greenhouse is a tool that enables you to keep your plants a little warmer than they would be outside. Greenhouses do more than just heat the air though!
- They create a more humid environment
- They help you to manage and vary light levels (the roof can be painted or covered at certain time or artificial lights can be used)
- They provide a cleaner environment (plants inside the greenhouse can be isolated from diseases and pests that are outside)
- They can provide a cooler environment (because it is enclosed, it is possible to cool the plants using fans and vents, even on a very hot day)
Greenhouses are complex environments, and there are many interactions between the different aspects of the environment that influence plant growth. For example, a greenhouse which lets in lots of light may become too hot for some plants. If you open the vents or doors, you may cool the temperature inside the greenhouse, but at the same time, you may be changing the balance of gases in the air.
GREENHOUSE MANAGEMENT INVOLVES GIVING CAREFUL CONSIDERATION TO THE FULL IMPLICATIONS OF EVERY ACTION YOU TAKE
Environmental Factors that affect Plant Growth:
- Atmospheric Temperature – the air
- Root Zone Temperature – in the soil, soilless, or hydroponic media in which the plant roots are growing
- Water Temperature – the water that you irrigate the plants with
- Light Conditions – shaded, full light, dark
- Atmospheric gas – plants give off oxygen but take in carbon dioxide. Animals do the reverse. Normally they balance each other, but when plants are locked in a closed room or housed by themselves, they become starved for carbon dioxide as the oxygen level in the 'room' rises.
- Air movement – mixes gases, evens out temperature.
- Atmospheric Moisture – humidity
- Root Zone Moisture – water levels in the soil or media
What Plants will you Grow?
Before establishing a greenhouse, small or large, you should decide on its main purpose, then set up the type of house that best suits the purpose. Here are some common reasons why greenhouses are set up.
- To propagate new plants. Greenhouses provide the ideal conditions for seeds to germinate or cuttings to initiate the growth of roots.
- To grow tropical plants or indoor plants in cooler climates.
- To protect plants which are cold or frost sensitive over winter.
- To grow crops of vegetables, cut flowers or berry fruits out of season or faster than what might be achieved outside.
- To grow young pot plants over winter when there may not be much growth in the outside environment.
You will also need to think about the types of plants you will grow in the greenhouse. Do you intend to grow a collection of one type of plant, or a variety of different plants? You will then need to find out the plants’ optimum growing conditions. Different plants have different requirements, and it may not be possible to grow a wide variety of plants in the greenhouse and get the very best out of each one.
There is a huge variety of equipment available to help cool, heat, light, shade, ventilate or humidify a greenhouse, helping you to manage and achieve optimum growth from your plants. Check out a couple of greenhouse companies, and ask them about equipment. They all have their pros and cons; and as with most things, you will get largely what you pay for.
You should first consider the materials that make up your greenhouse. This will decide the shape of the structure, how it can be ventilated and how it will be shaded. For example, a greenhouse with glass windows can be ventilated by opening the windows or can be painted to shade the greenhouse in warmer weather.
The next thing is to decide on how plants will be stored within the greenhouse. Wire benches are desirable as they allow the pots to drain freely, and reduce the risk of disease spreading between the plants. Shelves should be arranged to maximise the available growing space.
Other materials that can be included in a greenhouse are irrigation systems, exhaust fans, lamps for extending the growing period, heaters and even benches to support hydroponic growing systems. The selection of equipment will be decided by the climatic conditions where you live and the growing requirements of the plants you want to grow.