With the rising popularity of indoor growing systems like the Aerogarden™, more and more people have become interested in growing hydroponic vegetables and other plants. Hydroponics is a method of growing plants without soil, and it has some distinct advantages over traditional soil-based growing methods.
Hydroponics allows you to grow plants all year long indoors. Surprisingly, hydroponic growing uses less water overall than traditional soil-based systems. Plants grown this way also tend to grow faster and produce higher yields. Since most hydroponic plants are grown indoors, you also can avoid many of the typical garden pests and diseases you would encounter if growing outside.
Hydroponic Growing Systems
Most home-based hydroponic systems are categorized as “Deep Water Culture”. In this type of system, the plants are suspended above a tank of water with the roots hanging into the container where they absorb water and nutrients. These systems are inexpensive and easy to maintain and expand.
You can buy premade systems, but it is pretty easy to build your own system with some inexpensive components.
What you need to build a hydroponic system:
- A container for holding water. This could be a bucket or storage tub. The size of the container depends on the size of the plants you want to grow.
- A lid or flotation device to hold the plants. This could be the lid of the storage tub with holes drilled into it or a piece of styrofoam with holes that will float on the surface of the water.
- A support structure for your plants. Many systems use net pots or pods with some type of substrate that allows plant roots to penetrate to reach the water and nutrients. Common substrates include rock wool and coconut coir.
- Lighting. Since many plants need anywhere from 6-16 hours of sunlight, a broad-spectrum lighting source is necessary when growing inside. A wide variety of LED grow lights are available that provide both the red and blue light that plants prefer.
- Aeration. Plants need oxygen as well as water and nutrients to thrive. You can use passive aeration by setting up your system so there is a gap between the plants and the water allowing only 1/3 to 1/2 of the roots to be submerged. A more popular option is to use an airstone or recirculating submersible pump. Both airstones and submersible pumps are easily found where you would purchase aquarium supplies and are relatively inexpensive.
- Nutrients. There are 17 nutrients that plants require to develop properly. 3 of them (carbon, hydrogen, and oxygen) are existing in your hydroponic system. The rest you must supply through an appropriate fertilizer. These nutrients are nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, manganese, iron, copper, zinc, boron, molybdenum, chlorine, and nickel. There are many high-quality hydroponic fertilizers on the market. Keep in mind that different plants may have different nutritional needs, so you may not be able to plant them together. For example, you could grow kale and lettuce together, because they need the same amount of fertilizer, but not kale and tomatoes because tomatoes need more nutrients.
- Water. Plants do best in water that has a neutral pH somewhere between 5.4 and 7. It is a good idea to test your water both before and after you add your fertilizer as some fertilizers may affect the pH of your water. The electrical conductivity of your water can also play a role. The electrical conductivity (EC) measures the concentration of nutrients in the water. For a deeper understanding of pH and EC, you can read more here.
There are no such things as specifically hydroponic seeds; however, there are certain seed varieties that are known to thrive in hydroponic systems. When choosing your plants, consider how much light and heat you have available.
For indoor growing, lettuce, herbs, and other greens like kale, swiss chard or mustard greens are popular choices. For outdoor growing in the summer, as long as you have a big enough container system, almost anything can be grown hydroponically. Popular outdoor plants include strawberries, tomatoes, and cucumbers.
Aerogarden™ and other popular indoor commercial hydroponic systems come with pods that may already contain seeds, or you can purchase pods and add your own seeds. These pods consist of a framework and a growing substrate to support the seeds and plants. You can also start seeds in rock wool or coconut coir that you will transfer into your net baskets once they have developed into seedlings. Seeds can be started in a standard soil mix as well. You should just rinse the soil away from the roots before adding them to your growing system.
Hydroponic growth requires attention to be successful. You will need to regularly monitor water levels and nutrient levels so that roots are only partially submerged and have the right concentrations of nutrients.
Because of the warm moist environment, you will have to be watchful for diseases caused by bacteria, viruses, and fungi. Mildew and root rot are the most common diseases. Always work with clean hands and make sure there is adequate space between plants and systems to help encourage airflow and prevent disease. You should also always remove excess plant debris and diseased plants as soon as possible.
When changing out the system between growth cycles, be sure to clean and sanitize all parts of the system. First, wash with a mild dish soap and rinse well, then sanitize with a bleach solution of 1 tablespoon of bleach in one gallon of water. Allow everything to air dry well before restarting your system.
Just as with maintenance, you should always use clean hands and sterile tools when harvesting from your hydroponic garden. If you are pulling up entire plants, try not to allow water from roots to drip on the edible parts of the plants.
Lettuces and herbs can often be harvested multiple times. Simply cut the most mature parts of the plant and allow the rest to continue to grow. You will eventually notice a slowdown in plant growth over time and that is when it is time to pull the mature plants and start with new ones.
Hydroponic gardening is a popular choice for growing in a limited space or if you want more control over the growing conditions of your food supply. It allows you to produce fresh food in almost any location and have fresh herbs and vegetables throughout the year. Growing systems can be store-bought or made by the clever DIY enthusiast, but once set up, with proper care and attention, hydroponic gardening can be a rewarding and successful way to grow plants.