Because hydroponic systems are soil-less, the nutrients that are normally found in garden soil are not present in hydroponic systems. Therefore, we need to "feed" the plants grown in these systems with a solution of fertilizer that contains all the nutrients required by these plants.
The accompanying chart shows the amount of actual nutrient elements needed for proper growth. The first 3 elements (N,P,K) are the primary elements found in all fertilizers. The other elements are considered secondary and each plant has its own specific requirement for which and how much of each secondary element is needed.
A typical hydroponic solution formula will combine these elements in the proper ratio to ensure proper feeding at 3 different stages of a plants life cycle.
Stage 1 is the "seedling stage" which is when leaves begin to form. The first 2 leaves at the top of the plant are not really leaves but are lobes. The next set of leaves to form are called "true" leaves and signal that the plant is now going into the second stage. This first stage takes about 4-6 weeks and the plant requires a specific ratio and density of nutrients throughout this stage.
When you plant the standard way, in garden soil, the soil provides most of the nutrients you need and the rest come from the air and water.
But, in hydroponics you are not using soil. You are using water only, so you need to add the missing nutrition elements to the water to make a nutrient solution that the plant roots can access to provide food to the plant for growth development. This section describes 2 ways that can be accomplished. The first is complicated, but the second is easy. Please read on.
You don't have to be a mad scientist to make your own hydroponic formulas. You just have to understand how 16 chemical elements work together to provide the best liquid "food" for plants grown hydroponically.
Three of those 16 elements are found in the air and water. They are C(arbon), O(xygen), and H(ydrogen). The other 13 are listed in 2 categories; Macros, and Micros.
The Macros consist of 6 total elements, all of which play major roles in plant development. They start with the 3 main elements needed by all plants and they are N(itrogen, P(hosphorous), and K for potassium. The 3 letters N, P, and K are always shown on the front label of any fertilizer you can buy commercially, but they usually appear as just numbers such as 10-15-12. These numbers indicate the relative percentages of the elements found in the formula and are always listed in the order of N, P, and K.
The other 3 macros are C(alcium), M(agnesium), and S(odium), each of which play large roles in plant development but less than the N, P, and K macors.
The Micros make up the other 7 elements (of the 13 total) which are used in very small amounts but each plays a very important part in providing proper nutrition for the plants. In alphabetical order they are: Boron, Chlorine, Copper, Iron, Magnesium, Molybdenum, and Zinc.
We do not need to purchase these elements in the raw state however. We actually buy them as: MgSO4*7 H2O (Magnesium Sulfate), H3BO3 (Boric Acid), KH2PO4 (Monopotassium Phosphate), MnCl2*4H2O (Manganous Chloride), KNO3 (Potassium Nitrate), CuCl2*(2H2O) (Cupric Chloride), K2SO4 (Potassium Sulfate), MoO3 (Molybdenum trioxide), Ca(NO3)2 (Calcium Nitrate), ZnSO4*7H2O (Zinc Sulfate), Fe 330 – Chelated iron. When these products are used in our formulas they will automatically break down and combine into the elements needed.
Now, don't worry...I'm not going to get into fancy chemical class jargon here. Actually I just wanted to show you what is needed if you want to make your own "official" formulas for hydroponics. You can Google for actual formulas, or purchase books with that detailed information...it is beyond the scope of this discussion.
BUT, I am now going to tell you how to make the "unofficial" formula you can make very easily using only 3 readily available products.
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All you need is some Miracle-Gro (or equivalent brand) All Purpose Plant Food to start. Make sure the ingredient list shows NPK of approximately 24-8-16 and that the list contains a bunch of extra elements such as boron, copper, manganese, etc. You can find it anywhere.
Next you'll need a container of basic Epsom salts. You can find this at hardware stores, supermarkets, and online.
Lastly you'll need some calcium nitrate. Make sure the label states that it 15.5-0-0 NPK. This can be found in most hardware stores, Wal-Mart, hobby shops, and garden centers.
You'll be mixing these items with water. Most tap water is fine, but let it sit for 24 hours to eliminate the chlorine, assuming you have chlorinated water. For best results though, use only distilled water (available at supermarkets for about $1 per gallon) or use reverse osmosis filtered water if you use that as your home water filter method).
The second stage is called the "vegetative stage" and begins after the true leaves have grown. It will last for 4 to 6 weeks as the plant focuses on growth and establishing a solid root system. Foliage begins to appear through photosynthesis and the plant requires more nitrogen and lower amounts of phosphourus and potassium, so the nutrient formula ratio must be altered.
The third and final stage is called the "flowering, or blooming stage" when the plant forms flowers and fruit. This stage can last up to 16 weeks or more, and the nitrogen level needs to be reduced as the phosphorous and potassium levels need to be increased. Therefore, the nutrient formula must also change to accomodate this.
As you can see, the feeding of hydroponic plants requires 3 different formulations as the plants go through their total growth cycle. If the formulations are not correct the plants may not survive.
Fortunately there are prepared formulated fertilizer products available to us that provide exactly what is needed for proper hydroponic plant growth. They are available as concentrated liquids or granules and you just need to add water and fill your reservoirs with the right solution at the right time.
The photo shows the 3 stage system from General Hydroponics, the most popular liquid hydroponic nutrient supplier in the United States. Each bottle of concentrate is used for all three stages of growth. The labels have instructions for when and how much to use. You simply add the recommended amount of each to a gallon of water and use that as your nutrient solution.
Granular nutrient formulations are also available and are less expensive than the liquid versions. But, I find the granular versions are much more difficult to add to water. It takes a lot of mixing and blending to get the granules to dissolve while the liquid versions mix immediately.
In recent years, hydroponic gardeners have come up with home-made versions of the nutrient formulations in an effort to save money and to create easier to use products. I'll discuss this approach in the next section.
First, I'll explain the chemicals needed, but then I'll tell you about a short cut that allows you to purchase just 3 products that will make up a perfect liquid solution you can use diluted, at different ratios with water, for any hydroponic system.
The methodology is that the Miracle Gro contains most of the 13 elements listed in the section above, and the Epsom salts and calcium nitrate provide the rest. All we have to do is mix them in the proper order and weight to get a concentrate that we can then use to make many gallons of hydroponic solution for a fraction of what it would cost to buy it pre-made.
If you have looked for DIY hydroponic formulas before you may have noticed that most of the "experts" state that you should NOT used Miracle-Gro. Please forget that you ever saw that. I have found that many of these experts are purists who do not want to have an "all purpose" hydroponic solution, but would rather go to the immense amount of work to purchase and specifically mix all the individual 13 elements needed, in order to give specific plants a very specific feeding to maximize their efforts. On the other hand, I believe the extra work just isn't worth the very slight differences between what they are doing and what I want to do. I am looking to provide my family and friends with fresh, tasty, inexpensive food in a hydroponic method, and I am not interested in getting certifications or my name in lights to accomplish that. If you wish to take that route by all means do so, but my web site is presented as a way of having gardens that are easy to grow things and don't take a ton of work or money to have. So...let me present "Grand Dad's All-purpose Hydroponic Nutrients Concentrate formula".
Purchase these 3 products: (buy small containers to start with)
- Miracle-Gro all purpose soluble NPK fertilizer with trace elements
- Calcium Nitrate - water soluble (15.5%)
- Epsom salts
To make Main Concentrates - (stock solution to be diluted for final use), do the following:
Make 2 products - A and B, as follows:
A = Into 1 cup warm water, stir 2-1/2 tbsp. Miracle-Gro, 1-1/4 tbsp. Epsom salts, mix well.
B = into 1 cup warm water, stir 2-1/2 tbsp. calcium nitrate, mix well .
(These can be stored in individual containers for future use. DO NOT MIX TOGETHER YET - KEEP A & B SEPARATE UNTIL READY TO USE IN FINAL SOLUTION)
To create the final solution - (to be used for any hydroponic system):
In 1 quart of warm water, stir in 1 tsp of product A. Then, in the same 1 quart of water, stir in 1 tsp of product B.
The solution is now diluted 200 to 1 and ready for immediate use.
For stage 1 seedlings, further dilute the solution by mixing 1 part water to 1 part solution.
For stage 2 and stage 3 growth, do not further dilute the solution, just use as is.