Hydroponic Nutrient Solutions
Most plant problems are a result of using the wrong amount of fertilizer. Too little and your plants are weak and underfed, too much and you can burn the plant and even kill it. In most cases, it is a judgment call and requires constant monitoring and adjusting as the plant matures. This section contains general guidelines that apply to fertilizing most types of plants.
Hydroponic nutrient solutions are sold in concentrated form and added to your indoor garden's water supply at a certain ratio. The ideal concentration for your hydroponic solution is about 150-600 parts per million (ppm). For most plants, you can narrow that range down to 300-400 ppm. They are typically sold in two or three parts because some of the nutrients cannot be combined directly. Always mix each part of your nutrient solution directly into the water, never into another nutrient type.
How Much Hydroponic Nutrient Solution?
Plants require different proportions of nutrients during vegetation and flowering. Modern nutrient products are far more advanced than their earlier counterparts and now allow precise adjustments based on growth stage. Most hydroponic nutrient solutions are sold in a "growth" or "grow" formula for the vegetative growth phase and a "bloom" or "flower" formula for the flowering phase of the growth cycle. You should at least switch to the bloom formula because your yield will increase exponentially if you can max out your plant's capacity during the flowering stage.
A weak nutrient solution should be used for plants in poor growing conditions, such as low light, overheated gardens, and root-bound or crowded plants. It is also ideal for newly rooted cuttings and plants in the process of being transplanted or in transition between growing cycles.
Regular strength solution is fine for normal, healthy plants in ideal growing conditions. In rare conditions, you may be able to increase the fertilizer strength to capitalize on the efficiency of your garden. This only works if you have high quality lighting, ventiliation, and CO2 production that will allow your plants to grow fast enough to handle the extra feedings. Always make sure to increase the fertilizer strength gradually to avoid burning the plant.
In addition to the basic types of hydroponic nutrient solution, there are also various additives you can purchase to boost your plant's growth. Keep good records in your growlog of what additives are used, when they were applied, and the results (good or bad). This will give you a good reference guide on what worked and what didn't work for your future grows. Flush your hydroponic system immediately if you see any signs of an adverse reaction.
How to Measure Hydroponic Nutrient Solutions
The concentration of nutrients in your hydroponic nutrient solution is usually measured by the electrical conductivity of the dissolved minerals in the water. The unit of measure is parts per million (ppm), but this only measures the total conductivity of the solution, not the relative strength of the various minerals. This is another reason why most hydroponic nutrient solutions are sold as a mix of 3 parts instead of by individual nutrient. Once you have the correct mix between the parts, it is easy to add to or dilute the solution to achieve the correct conductivity.
Over-use of Hydroponic Fertilizer
If you see any signs of over-fertlization, you should immediately flush out your growing medium to allow the plant to recover before further damage is done. Use only clean water until the plant shows symptoms of nutrient deficiency. Then you may resume your normal feeding schedule. Depending on your hydroponic system, flushing may require top down watering to completely clean out the medium.
Another good time to do a complete flush of the plant and medium is around 2 weeks before your expected harvest date. That will help prevent the vegetables from tasting like your hydroponic nutrient solution.