Larger Scale Organic System

by Doug Adell
(Wilkesboro, NC)

We are currently leaning toward a raft system, similar to your deep water culture system, with a focus on baby greens. The tank that we are considering will be 12' x 84' long x 8" deep in a greenhouse setting. The greens will be propagated in a soilless mixture in small cups (with holes for root penetration) under grow lights, then transferred to the rafts, where they will be spaced 4" apart. The greens will then be harvested 10 days later. What nutrient and nutrient level would you recommend?

Answer: Doug- plants such as lettuce, herbs, and spinach will all do very well in the same hydroponic system. They also all produce edible parts during the vegetative stage, which means there is no need to ever give them any bloom fertilizer or expose them to a 12-12 light cycle. These plants should do well on a 50% strength vegetative formula, which (usually) is highest in Nitrogen. This will come out to about 700 ppm on most TDS meters.

Most hydroponic nutrients cover all the bases, nutritionally, pretty well....just be sure to use the veg formula of whatever nutrient you decide to go with. Some choices when it comes to organic hydroponic fertilizers are:

Canna Bio- a one part fertilizer, and also the correct pH straight out of the bottle (making it a VERY easy fertilizer to use and manage). Also, it is made using NO animal products.

Pure Blend Pro- Check out my post here for a complete recipe.

Some additional organic options would be General Hydroponics General Organics, Earth Juice (which requires a lot of pH adjustment), or Roots Organics. Simply follow the recipe for mixing up a veg formula for any one of these, than make sure you dilute it to the appropriate strength and check/adjust the pH. For more detailed information on maintaining the nutrients in your reservoir, check out my how to grow hydro page.

One final thought before I let you go. If you are growing several different varieties using the same nutrient solution, one of those varieties is bound to be slightly more sensitive to over-fertilization than the others. Make sure to inspect the leaves of EACH variety EVERY DAY, keeping an eye out for the first signs of a problem (such as leaf tip burn). If you notice any, you will want to consider your recent nutrient strength the "upper limit", and it may be a good idea to dial back the strength just a tiny bit to keep everyone happy. I hope this helps you out Doug....I would love an update when things get a little further along!