There are many challenges to transitioning from traditional soil gardening to indoor or hydroponic methods. Understanding some basic concepts can greatly improve the performance of your system and, in turn, the health of your plants. Here are some common mistakes to avoid.
Not Regulating Water Temperature
We’ve all seen potted plants thriving in hot outdoor conditions, so why would the temperature of your hydroponic nutrient solution matter? The main reason it’s important to keep your reservoir cool has to do with dissolved oxygen. As water temperature rises, the solubility of oxygen decreases. Even with the addition of air stones or hydrogen peroxide, the nutrient solution simply won’t be able to deliver adequate oxygen to your plants’ roots. This is especially important in deep water culture systems where roots are constantly suspended in water. Low water temperatures can also have negative effects on your garden. Hydroponic nutrients aren’t as soluble in cold water, and below a certain temperature many minerals will precipitate out of the solution where they are no longer available to your plants. Cold water can also lower the overall temperature of your plants, slowing metabolism. Chillers and reservoir heaters should be used to keep your solution between 55-70°F.
Using the Wrong Nutrients
There are more plant food products on the market today than could easily be counted, but most are not suitable for hydroponic use. Too often consumers buy products based on marketing or NPK numbers without considering the function of their system. Granular and organic products are designed to break down slowly, whereas mineral-based liquid fertilizers tend to be more readily available to the plant. Your local hydro store can help find the best solution for your system.
Paying too little attention to pH…or too much
Each essential plant nutrient is absorbed by the roots within a specific pH range. The majority of minerals such as nitrogen and calcium are absorbed well at a neutral pH of 7.0. Other important nutrients like iron are better absorbed at a lower pH. Soil provides some buffer against pH lockout, but it’s important to keep a hydroponic system within an appropriate range so that every essential nutrient is available to the plant. For most scenarios this range will fall between 5.5 and 6.5. Over time, various factors will cause the pH of the nutrient solution to drift. When the pH moves outside the appropriate range, a concentrated acid or base can be added to correct the imbalance. While it’s important to keep the solution within the right range, don’t focus too much on any particular number; overuse of pH adjusters will alter the chemistry of your system, leading to more problems.
Relying on Trendy Passive Hydroponic Methods
Many people looking for the simplest way to try hydroponics will turn to passive methods such as the growing style developed by University of Hawaii researcher, Bernard Kratky. In the Kratky method, plants are suspended above a reservoir of nutrient solution without the use of circulating pumps or air stones. While this is a great low-maintenance approach for students and hobby growers, it lacks one of the main benefits of growing hydroponically, which is ability to boost oxygen at the root zone. Plants take in oxygen through their stomata as well as their roots, and keeping your nutrient solution oxygenated will also prevent the growth of harmful pathogens. The performance of your hydroponic system can be greatly enhanced with the addition of a single air stone or small circulating pump.
Ignoring Soilless Media
One way to get the performance of hydroponics with the ease of soil gardening is through the use of a soilless grow medium such as coconut coir. These substrates can be used alone or combined with aeration materials like perlite to create soil-like blends. Use it in normal plastic or fabric nursery pots and water with a hydroponic nutrient solution (by hand or drip irrigation). This method provides a buffer against pH and moisture fluctuations, and you won’t have to worry about a small mechanical failure killing your plants. At Garden Grove Organics, we’ve spent years developing our very own custom soilless medium, Easy pH Mix. A favorite of our customers, the Easy pH Mix combines incredible pH stability along with great aeration and drainage properties. Find it here.