Using Organic Fertilizers in a Hydroponics System
What are hydroponics?
Hydroponics is a soilless growing medium in which you grow plants in liquid. Generally they are grown in a nutrient solution mixed with water. Down below we teach you how to prepare a soilless growing medium.
Preparing a soilless Media in 4 easy steps:
- Start out with your base material, either peat moss or coco. Since both are mineral based, perline and/or vermiculite can be added to aid in aeration and water retention.
- Add a mineral component at 5-10% of the total mixture ✱ (we recommend sand or clay as they are cheap and easy). Insoluble plant nutrients can also be added at this point (we recommend lime or rock phosphate).
- Add compost at 10% of the total mixture ✱ (we recommend worm castings).
- Prime the medium before planting with Future Harvest’s Royal Black. This will allow more time for the breakdown of the humic acid into fulvic acid, as well as chelate any nutrients present in the medium.
✱ For example we want 100 liters of soilless medium so we’d make a blend of 80 liters of coco, 10 liters of sand and 10 liters of worm castings. ✱
How often should I use nutrients?
As a general guideline when growing with conventional nutrients in a soilless medium we recommend feeding the plants every other day and inbetween to give 2 rounds of straight water. Feeding and watering are based on how much water the plant goes through.
What does solubility mean?
Before we introduce the nutrients you have to understand solubility. Solubility is a nutrient's ability to be dissolved in water. Given this, nutrients that are insoluble need time to break down and in many cases take years to dissolve. This can be the biggest obstacle for organic growers but with a bit of knowledge and planning it can be overcome!
What nutrients should I use?
Nutrients that are insoluble need time to break down.
Sources of Nitrogen:
- Animal Waste: unfortunately, animal waste is the most common and easily available source of organic nitrogen. Of these, fish emulsion is the most readily broken down and the easiest to use.
- Plant based amino acids: these are another great option, but they can be difficult to find.
- Sodium Nitrate: this mineral salt is permitted by some but not all organic authorities. It is high in nitrogen but the sodium component can stay in the soil and increase the salinity. Long term usage can result in serious damage to the soil.
Sources of Phosphorus:
Some sources of nutrients are organic, but not vegan.
Bone meal: this source of phosphorus breaks down easier than rock phosphate. However, use of bone meal results in the grow not being considered vegan, which could be an issue for some organic growers.
Fruit bat guano: this source of organic phosphorus is most easily broken down and should be used as a dressing on top of the media. Because it is a very limited resource, the price is quite high.
Fruit bat guano is a good source of phosphorus.
Sources of Potassium:
- Potassium sulfate: this is the most obvious choice as it is highly soluble, fairly inexpensive, and has no restrictions on its usage.
- Kelp: kelp contains decent amounts of potassium but may need extra time for the potassium to become available
Sources of Calcium:
When dealing with plant nutrition, organic or otherwise, calcium poses a problem as it reacts with other nutrients which results in them becoming locked. When searching for a source of calcium to use be aware of possible reactions.
- Calcium Carbonate: this is the most common and cheapest form of calcium. It is the major ingredient in lime, egg shells, and oyster shells. Calcium carbonate can push up the pH, but the calcium can be freed up in an acidic environment.
- Organical Magic: this organic nutrient by Future Harvest is OMRI Listed and is a soluble source of liquid calcium. It has been formulated based on the traditional cal-mag products used in the hydroponic industry.
Sources of Sulfur and Magnesium:
These nutrients shouldn’t be a problem to obtain as both sulfur and magnesium are found in soluble minerals. Sulfur can be found together with several of the other nutrients and will be soluble - with the exception of calcium sulfate.
- Epsom salt: otherwise known as magnesium sulfate, is a great natural source of sulfur and magnesium.
Iron: pay the most attention to iron as it is needed in the highest amounts and can be very unstable. If brown particles are seen on the bottom of the nutrient mixing container, it is likely the iron has fallen out.
Boron: in the form of borax. It is a fairly easy option as it is cheap and readily available.
Molybdenum: this can most likely be left out, since the amount required is miniscule and it’s expensive and hard to source.
Make sure your products are organically certified by a third party!
Growing hydroponically with standard hydroponic nutrients is very straightforward. Using organic nutrients can be a bit more challenging but with a bit of patience and an understanding of where the nutrients are coming from it should be fairly easy to grow a crop using this method.