If you have a very small hydroponic unit, whether homemade or bought, you may not feel that you wish to go to all the bother of making your own nutrients. If this is so, it is quite easy to obtain commercial nutrients in from one to twenty-five pound containers.
Ordinarily, the novice hydroponic gardener knows relatively little of chemistry. Using a pre-mixed nutrient is the most straightforward way of assuring that your plants get a balanced diet. There are good hydroponic nutrients on the market that have all the necessary trace elements. They can be bought at many large nurseries and plant stores or from some of the suppliers listed at the back of this book. If it becomes necessary to adjust your nutrient at some point, it is certainly easier for the grower who lacks chemical knowledge to be using an identifiable ready-made nutrient.
When purchasing commercial hydroponic nutrient, its quality is identified with three digits separated by hyphens, such as 20-20-20. These numbers represent the percentage by weight of the three main elements present: nitrogen, phosphorus and potassium. There are various nutrients on the market that have different ratios, but, generally speaking, they are all well balanced. Commercial nutrients have their drawbacks, however, because most users of soilless gardens are growing a wide variety of vegetables at the same time, and it is impossible to provide a specific plant food for each different vegetable at each stage of its growth. The only answer would be to have a different type of plant in each container, a solution to the problem that would often prove too expensive and space-consuming. When using a commercial nutrient, I have found it a good idea at the bud development stage of flowering vegetables such as cucumbers, peppers or tomatoes, to add a nutrient with a high middle number such as 10-52-10. Flush the system out and use half of the measured amount of the commercially made nutrient and half of the nutrient with the high phosphorus. Any nutrient with a high middle number will do. The increased amount of phosphorus will aid in healthy root and bud development. You should begin this treatment when buds first start to develop and for as long as this development continues.
Flushing is simply cleaning out your system of old nutrient, removing any salt and mineral build-up on your growing medium and putting in new nutrient solution.
Because it is difficult without a lab analysis to know just which nutrients have been used by the plants at any given time, it is cheaper and easier simply to replace the nutrient solution once a month (more frequently if desired). Here's how to do it.
Syphon or pump off the existing nutrient solution. Use this for your house plants or put it out in the backyard garden or around shrubs.
Fill the container to the top of the growing medium with plain water and leave it for about an hour and then syphon off and throw away. This dissolves the salt and mineral build-up. Now fill your reservoir again with fresh water and add the required amount of nutrient.
Once nutrient has been introduced to your hydroponic system according to the measured instructions, you will find that as the water evaporates or is used by the plants you will have to replace it. Do not keep adding nutrient! For the remainder of a month until flushing is again required, add only water. This is because the nutrient does not evaporate and if you keep adding nutrient your solution will become too saline.
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