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Introduction

Most consumers have purchased ‘hot house tomatoes’ or ‘vine ripe tomatoes’ in local supermarkets. These are all grown using a hydroponic system. We’ve all been eating hydroponic produce for years.


Why do commercial growers use hydroponic systems?
They do it because they can get two to three times the yield of a traditional soil crop. They are able to control the plant growth much better and they can control most bugs & diseases with biological controls as opposed to pesticides.

What is the difference between growing in soil/peat and growing hydroponically?

  • With soil or peat mixes, the potting mix changes over time. Although it might be a great mix in the beginning, it eventually starts to compact and leads to root bound plants.
  • Many people find it difficult to figure out when to water. By the time one sees a plant drooping from lack of water, it is often too late to save the plant.
  • With soil or peat mixes, part of the fertilizer and water poured into the pot or garden bed is not available to the plant.
  • The plant needs a huge network of roots to search for water and food.
  • When the plant cannot find the exact food it needs, it does not produce the quantity of flowers or size of tomatoes expected.
  • When a hydroponic growing medium, such as Grodan Rockwool, is used, such problems are avoided. How?
  • Grodan Rockwool is but a fancy container for plants.
  • With Rockwool, it’s a matter of simply adding water with plant food whenever the ‘container’ runs low.
  • The plant has easy access to all the water and food it needs. The container – the Rockwool -- holds nothing back.
  • The plant no longer needs the huge network of roots to find the food -- it is all right there.
  • The plant has far less bug and root disease problems because the “container” (the Rockwool) was completely clean when you started.
  • So when the plant doesn’t have to spend extra energy on searching for water and food and extra energy fighting bug and diseases, it has a lot of surplus energy! And where does the surplus energy go? The plant grows much faster and sets more flowers and better quality fruits.


Rockwool

-also known as stonewool and mineral fibers



See also Producing Rockwool

Rockwool is made from basalt rock and chalk. Mimicking Mother Nature’s production of “angel hair’ during volcanic activity, these rocks are melted at about 3,000º F. to create lava. This lava is blown into a spinning chamber, which makes fibers similar to cotton candy.

We choose to use Rockwool as the ‘container’ for the plant for the following reasons:


  • Plants require something in which to anchor their roots.
  • Rockwool has lots of little pockets that make excellent storage for water and air.
  • These little pockets encourage the plant to set lots of small fine roots. These are the “hair roots” that absorb the food. The thick roots anchor the plant and transport the food from the small roots.

  • More of the smaller fine roots mean more food for the plant and the faster it grows.
  • It is very easy to figure out when to water. When the weight of the container feels about half the weight of what it was after the last watering, it is time to water.
  • Water until the water runs out the bottom of the container. Grodan Rockwool can never be “water logged” if the excess water can run out freely.
  • If a tomato plant is wilting so bad that it’s almost “lying on the ground”, it still can be saved! Just water the Rockwool well and the plant will slowly rise up from the ground (you can actually see this happening).
  • In a soil mix, when a plant wilts, more than likely the plant has been fighting for days to survive and when in droops so much, it’s probably already past the wilting point. In Rockwool when the plant droops, it is because it is suddenly out of water and just adding some will revive the plant.
  • News articles regularly report about problems with farm fertilizers draining into in to the ground water. Grodan Rockwool as part of a hydroponic system allows for the re-circulation of the used water instead of just draining it to waste.


Rockwool and health

  • The vegetables efficiently grown on Grodan Rockwool all contribute to better food safety and health of the consumers.
  • Mist the Rockwool before you start working with it to minimize dust from the surface and to make it is easier to handle.
  • Nobody is allergic to rocks, so there is no need to worry about that.
  • Rockwool is one of the most studied fiber products in the world. Extensive inhalation studies spanning several decades have been conducted to determine if there are any health risks associated with Rockwool. Rockwool is a bio-soluble product and so dissolves in the human lungs. In 2001 WHO confirmed the safety of the product, by removing Rockwool from its lists of classified products. (MSDS)
  • A good example of how harmless the product is: most aquarium plants are grown in Grodan Rockwool and we have never seen an unhappy fish!

Re-use and recycling of Rockwool

  • Used Rockwool can (and is) being melted and spun into new Rockwool many times over.
  • The Rockwool in a home hobby system can and should be re-used, too. We recommend you use it for a different plant from the previous one in order to avoid any disease transfer.
  • Grodan cubes and slabs can be chopped up and used as a potting mix for container plants.
  • OR use the chopped pieces to mix in with compost piles. The extra air the product provides will greatly speed up the composting process.
  • The chopped product (or the granulated Rockwool) can be mixed into garden beds. This is especially good if the soil is heavy clay or very sandy. Rockwool gives more air and water to the plants.

Further information: Environment
What about plant fertilizer?
Hydroponic production is an environmentally friendly process. It minimizes fertilizer use by being a more efficient process than soil production.

There are a wide range of “organic” fertilizers that can be used in such a system. A plant can only eat or absorb molecules of food. Whether the calcium and nitrate comes from a cow, a bird or a chemical fertilizer it is the same molecules the plant eats. When the nutrient is delivered to the plant in organic form, you are essentially delivering the molecule 'wrapped' in an organic coating.

The plant roots must first strip of the 'wrapping' before they can absorb the food. If the plant is spending energy on searching for food, it has less energy to put into growth above ground. A good analogy are vitamins. Plants use fertilizers as we use vitamins to grow stronger. We can get our vitamins from organic food or from a vitamin bottle.


When using 'chemical fertilizers' it’s basically like giving a plant it’s vitamins from a bottle, the plant always has instant access to the whole range of plant nutrients, so you actually may end up with a tomato that has a better nutritional value as well as higher rate of growth. In addition in a controlled hydroponic environment, pest and disease control can be effectively managed without dangerous pesticides and often can be done with the almost exclusive use of biological control products.
If you are growing the 'true organic way' outdoors– by mixing manure, guano or organic fertilizer into the soil- each time you water your garden, you are washing nitrate into the ground water and everybody's drinking water, which is not good for any body

In fact in Northern Europe, for most crops, it is prohibited to grow produce without collecting the drain water and reusing it.

The perception that organic produce is more healthful than hydroponic produce is therefore false. It is the less use of pesticides that actually makes for more healthful produce, something which can be more easily accomplished with a hydroponic system. Also, it is better for the enviroment because the drain water can be collected and reused.


Ultimately when choosing fertilizer products one should look at the whole picture; Which products have the least negative impact on the environment, people and animals. This is in fact the way the European Eco label certification works.

Here are some links that explains the Organic versus Eco label.

http://www.eco-labels.org/article.cfm?ArticleID=121&ProdIssueID=2

http://europa.eu.int/comm/environment/ecolabel/index_en.htm

Did you know that for the Olympic games in Sydney hydroponic produce was exclusively bought for all the athletes? They chose hydro for the quality and assured timely delivery of the produce.