My number one organic hydroponic tip is this- pick a hydroponic system that does NOT use drip heads or spray nozzles. If you need to know, in general, how to mix up your nutrients and how to maintain your nutrient solution properly, that information is found over here-> hydroponics feeding tips.
One organic hydroponics feeding plan I found is simple, works very well,
and is less expensive than professional hydroponics fertilizers (which
are usually not organic, anyway). The plan is to use Maxsea, a seaweed based fertilizer that is affordable and relatively complete. For the first 7 days the plants have roots, I usually give them 400-500 ppm Maxsea 3-20-20, which is about one rounded teaspoon in a gallon of water. The extra Phosphorus is what really young plants are looking for to feed new root growth.
After this point, the higher nitrogen levels will no longer damage the
young plants, so I make the solution about 700-800 ppm Maxsea 16-16-16.
This is about two level teaspoons in one gallon of water. When the plants are switched to flowering, I use a 50/50 mix of Maxsea
16-16-16 and Maxsea 3-20-20 for the first two weeks (it takes about two
weeks for the plants to adjust and fully transition into flowering).
I used to use only the Maxsea 3-20-20, but the plants usually ended up a little nitrogen deficient before the end of flowering. The 50/50 mix at transition helps to keep a little more Nitrogen in the game till the very end of flowering. I try to keep the solution around 800 to 900 ppm during the transition period into flowering.
Finally, I switch to plain Maxsea 3-20-20 to finish (except for the
flush, of course). I keep the solution around 1000 ppm, which is about 3 level teaspoons
in a gallon of water. It is always best to us a TDS meter or EC meter
to check your nutrient strength! I have very detailed information on how
to maintain your nutrient solution properly from day to day over here.
Flushing a crop with plain water before harvest will improve the aroma and flavor of your produce. In a hydroponic system, this can be done with 7 days of plain water. It is helpful if you change the plain water with fresh water every day for these last days, but it is not absolutely necessary (and I don't). I DO, however, like to add a little Thrive Alive B1 and Liquid Karma to my "plain" water while flushing. They are a little different than nutrients-> They continue to drive cell division in the plant and help a great deal with the flavor of the plant, and especially in the resin production of the plant.
The only thing about Maxsea is that it is missing magnesium. Add 1/4 teaspoon Epsom salts to every gallon of nutrient solution and you will never have a problem with this.
Using Maxsea for organic hydroponics is great. It dissolves almost completely, with very little particulate matter, so there is less stress on your pumps. When you mix it up, it is nearly the perfect pH. This eliminates the need to purchase an expensive pH meter in the beginning (I still recommend getting a pH drop test kit- it's cheap).
Aside from being easier to check and correct for pH, Maxsea is a complete fertilizer (except for Magnesium). This also makes your feeding much more simple than it could be. Just be sure to include 1/4 tsp Epsom salts to every gallon of nutrient solution you mix up to include your Magnesium, and your good!
Because it is a seaweed based fertilizer, you do not need to supplement with liquid seaweed for trace nutrients. Seaweed is also high in plant hormones, eliminating the need to supplement for plant hormones in any way.
I have seen very few other systems this simple that produce top notch results like Maxsea does. Did I mention that it costs you less than professional hydroponic fertilizers? One of the only places I have been able to find the Maxsea fertilizers is Charley's Greenhouse and Garden. 2016 Update: they have it on Amazon too : )
Another popular feeding method when using organic hydroponics is to make a nutrient tea from worm castings and bat guano. You may want to add Maxicrop liquid seaweed and Thrive Alive B1 at 10 ml/gallon to add hormones and vitamins to the mix. These are two of the very best nutrient additives you can you can include, no matter what base nutrients you decide to go with.
For the vegetative stage, put two parts worm castings to one part high nitrogen bat guano to make your tea.
For the flowering stage, use one part worm castings to two parts high phosphorus bat guano to make your tea.
Place the organics in a sock or pillow case and make your tea in 3 to 5 gallons of water. Again, a TDS or EC meter is very helpful to tell how strong the nutrient solution is. Organics mixed in this way will seem to turn out a different strength every time.
Before you use the tea, determine how strong the nutrient solution SHOULD be, based on the stage of your plants life cycle. The tea will likely be stronger than you need. Simply add plain water until the solution is just the right strength.
Last, make sure you check and adjust nutrient solution to a pH of 6.0-6.2 before using.
Recently, two other "professional" organic feeding options have come to my attention. The first one is the Canna Bio line of nutrients. With Canna Bio, there is one fertilizer for the vegetative stage and one for the flowering stage. Not only are these fertilizers organic, they are vegan (they contain no animal products). Plus, they are one part fertilizers, which is unusual....most hydroponic fertilizers come in two or three parts that need to be mixed into solution. This makes them convenient to use, especially for those who are a little intimidated with mixing two or three part formulas.
These fertilizers also mix up at just the right pH, which is a great benefit. This makes it easier to maintain your nutrient solution every day. Instead of checking the nutrient strength (and adjusting it) than checking the pH (and adjusting it), with Canna Bio products you only need to check and adjust the strength of the solution.
When you don't have to check the pH of the nutrient solution all the time, you save money in two ways. First, you won't need to buy an expensive pH meter for checking the nutrient solution every day. Second, you won't need to buy pH UP or pH DOWN products to adjust the pH as often. When you add up all of the benefits, Canna Bio becomes a very friendly fertilizer to use (especially for beginners).
The second "professional" quality organic hydroponic fertilizer plan I have come across recently is a recipe (actually two) using Pure Blend Pro as the major nutrient. You should use this feeding plan only if you are comfortable with mixing up a three part nutrient solution, and if you are comfortable with checking and adjusting the nutrient strength AND pH every day (basic stuff, but it can be intimidating to a beginner).
For the vegetative stage use:
126 ml Cal-Mag Plus
180 ml Liquid Karma
540 ml Pure Blend Pro Vegetative Formula
For the flowering stage use:
126 ml Cal-Mag Plus
150 ml Sweet
180 ml Liquid Karma
540 ml Pure Blend Pro Bloom
The person I know who uses this formula mixes all of the ingredients in an empty milk jug, than adds the mixture slowly to the water in his nutrient reservoir until he reaches the desired nutrient solution strength. He than adjusts the pH to 5.8, which works very well for this formula.
It's important to note, you should NEVER mix normal hydroponic nutrients together in this way before adding them to the nutrient reservoir. If you mix chemical hydroponic nutrients together, they will chemically combine and will be useless to your plants as food....that is why they are bottled separately in two or three part formulas to begin with! When mixed into a nutrient reservoir full of water one at a time, this chemical interaction is not a big problem.
My friend has never noticed any problems from mixing together his nutrients in this way. The only reason for this, I guess, is that the nutrients are organic nutrients and not simply a positive(+) chemical ion and a negative(-) chemical ion that would join together as soon as they are mixed.
The only difference between hydroponics and organic hydroponics is what you choose to feed your plants. However, there are some hydroponic systems that do not work well with organic hydroponics. Even organics with very few particles floating around will still clog drip emitters and spray heads. For this reason I do not recommend hydroponic drip systems or aeroponic systems.
The hydroponic gardening methods best suited for use with your organic nutrients are...