The performance of a nutrient solution is not guaranteed by simply using a quality brand. Proper dosing procedures and ongoing maintenance are necessary to obtain maximum performance.
Ideally one formulated specifically for use with the medium being used. Be sure to use the associated additives as overall performance will often depend on these. The order in which you add different components is important, and so is the timing—seedling, vegetative or bloom. Always follow the dosage chart.
This helps to prevent diseases. Use either fresh reverse osmosis water (ideal due to its low nuisance salt content) or fresh treated tap water.
Always add the majority of water before adding nutrients and additives. Never mix any nutrients or additives together in their concentrated form. Once a nutrient or additive is added to the water, stir it well before adding the next. High pH additives should be added last, pre-diluted into a cup of water before being added, quickly stirred and the pH checked (Fig 2).
Check this once the total solution is made and ‘before’ feeding it to the plants. For most species, use the following as a guide:
Use a nutrient thermometer to monitor the temperature of your nutrient solution. The ideal is 68° F (20° C). Too warm and you risk promoting root diseases or suffocating the root zone with low dissolved oxygen levels. Too cold and you will shock the roots and slow plant metabolism to a crawl. Your nutrient solution should feel sort of “silky” and tepid—neither warm nor cold.
When hand watering or top feeding, do so slowly, evenly and gradually. Aim for around twenty percent of the nutrient solution to run out of the bottom of the pots. Run-off helps to keep the root zone cleaner with less salt build-up.
Water the surface of the medium at as many points as possible otherwise areas of the root-zone will risk being left un-watered. Devices such as water-rings or spray nozzles are a good alternative to single point drippers.
For run-to-waste coco coir or soil systems, periodically collect some of the run-off and check its EC. If it measures more than 0.5mS (500 µS or cF 5.0) above the EC of the input nutrient solution then consider flushing through with a milder solution (or even pure water) to help clear the root zone of excess salts. For example, if the nutrient solution has EC 1.7mS but your run-off measures 2.3mS (or more) then it is time to flush.
Hard water is typically alkaline—and so are many nutrient additives. “Alkalinity” is what typically drives nutrient pH above and beyond 6.5. This is the point at which many trace elements (e.g. iron) begin to destabilize.
Andrew Taylor is the Chief Chemist at FloraMax. You can visit their website at Floramax.com.