Hydroponics is one of the fastest growing (pun indented) sections of the horticulture industry. Heightened control, cleanliness and increased vegetative growth are all benefits a gardener can gain when using hydroponics in a garden. The concept of soilless growing may be intimidating to some growers and many times, it is this intimidation that keeps certain gardeners from experimenting with hydroponics. A great way for a hobbyist to begin his or her experimentation with hydroponics is to build a hydroponic planter. This way the gardener can experiment with hydroponics without spending a lot of money or dedicating an entire crop to uncertain results. In fact, for less than fifty dollars a gardener can build a self-contained hydroponic system that is capable of growing a wide variety of plants. This system can be built from supplies found at most home repair, nursery and indoor garden retailers or online.
Before breaking down each component of the do-it-yourself hydroponic system, a closer look should be taken at the type of hydroponic system that will be built. “Hydroponics” is a general term referring to soilless growing and there are many types of systems that can be defined as “hydroponic systems”. This article will explain the Deep Water Culture, or DWC, hydroponic system. In a DWC system, the plant is supported above the nutrient solution in an inert medium. The medium is in place to stabilize the plant and does not provide any nutritional value.
Although there is some variance between DWC systems, the overall concept is the same: after the plant’s roots grow through the medium, they will enter the nutrient solution and continue to grow there. All the nutrients that the plant needs will be provided by the nutrient solution. The roots will actually stay submerged in the nutrient solution throughout the plant’s life cycle. Submerged roots can sometimes “drown” because the oxygen content in the solution can quickly become depleted. This is why, for a DWC system to work properly, air (oxygen) needs to be delivered to the nutrient solution. To ensure an adequate amount of oxygen is available to the plant’s roots, most DWC systems have a continuous supply of air going directly into the nutrient solution. This direct supply of oxygen, combined with the readily available essential elements provided by the nutrient solution, creates accelerated plant growth which is the biggest advantage of a DWC system. With a few basic components any hobbyist can build and experiment with his or her own DWC hydroponic system.
The following is a list of supplies a grower will need to build a stand-alone deep water culture planter (included is an estimated cost for each component):
The 5 gallon bucket is the reservoir for the nutrient solution and is where the majority of the plant’s roots will be housed. If you are planning to grow any consumable plants within the system, it is important to get a five gallon bucket that is food-grade. Non-food-grade plastics contain chemicals that could leach into the nutrient solution and end up damaging the plants. Black is the preferred bucket color as it prevents light from entering the root zone. Buckets of other colors may be used but should be wrapped in tinfoil or black plastic to ensure light exposure to the roots is reduced.
Mesh bucket lids are special lids designed for pond filters and hydroponic systems. They can be purchased at most indoor garden retailers or at a pond supply store. Many home building centers that carry pond supplies will also stock mesh bucket lids. In a DWC system, this specialized lid holds the inert medium and the base of the plant. The medium, combined with the mesh pot, gives support to the plant as it grows. Although it is far easier to purchase a mesh bucket lid for this project, a gardener can also make a mesh bucket lid from a standard bucket lid and a 4” – 6” mesh pot. A hole that is slightly smaller than the top rim of the mesh pot should be cut in the center of the bucket lid. This way when the lid is placed on the bucket, the mesh pot can hang in the bucket without falling through.
Clay pebbles, also known as hydroton, are my preferred medium for DWC systems. If clay pebbles aren’t available, another inert medium can be used. However, the medium will get some moisture from the humidity within the bucket so a medium that holds a lot of moisture should be avoided. Remember, the plant will not be receiving nutrients from this medium and its main purpose is to house the base of the plant and give the plant stability.
A small aquarium air pump will be the life line for the DWC system by supplying the air to the nutrient solution. Just about any small aquarium pump with a 1/4 inch air outlet will suffice.
A small amount of 1/4 inch clear vinyl tubing will be needed to connect the air pump to the aquarium air stone. Many hardware and home repair stores offer tubing by the foot.
An aquarium air stone, or air diffuser, is a small stone with a 1/4 inch air inlet attached. The purpose of the air stone is to diffuse the air into multiple tiny bubbles. This helps to break the water’s surface tension and increase the amount of dissolved oxygen in the nutrient solution.
A visit to your friendly neighborhood indoor garden retailer or an online hydroponic retailer will provide an array of nutrients to choose from. Don’t become overwhelmed with all the choices. All that is needed for hobbyists experimenting with hydroponics is a general hydroponic fertilizer. Most hydroponic fertilizers come as a concentrate and are diluted in water to create the nutrient solution.
After purchasing all the needed components for a DWC system, a grower can start setting up the system. The first step is to thread the 1/4” vinyl tubing through the mesh bucket lid. This is so the lid can fit snuggly on the bucket and the air line can still reach the bottom of the bucket. Connect the air stone to the end of the tubing that will be inside of the bucket. Connect the other end of the tubing to the air pump. Next, partially fill the mesh bucket lid with rinsed medium (the clay pebbles or chosen medium should be thoroughly rinsed in order to remove any dust or dirt).
The next step is to fill the bucket with water to roughly one inch below the hanging mesh basket. In other words, there should not be standing water in the mesh basket and medium. The water level should be kept just below the bottom of the basket. The humidity created by the tiny bubbles will moisten the medium enough to promote healthy root growth. Lastly, add the proper amount of nutrient solution to the water in the bucket (there is usually about 3 1/2 – 4 gallons of water in the bucket when filled just below the bottom of the mesh basket). Follow the dilution ratio directions on the fertilizer label to create the nutrient solution.
After the system is set up, it is time to place the plant start or seed in the medium. Small plants should be transplanted into the medium in a fashion similar to transplanting into soil. Place the root mass in the mesh basket and cover with remaining medium. Seeds can be planted into the medium as well. However, seeds may require hand watering for the first few days until the roots have reached into the lower section of the mesh basket where the moisture will be. I have grown a wide variety of plants in DWC systems and just about any plant can be grown in a DWC system successfully. The only plants that should be avoided are cacti and succulents that do not need frequent watering. These types of plants can easily be overwatered in a DWC system and tend to be a bit finicky in hydroponic systems. After the plant or seed is in place, the air pump can be plugged in. In order to provide oxygen to the roots at all times, the air pump should run continuously.
Once the DWC system is up and running, there are a few things that should be done to make the system continue to operate efficiently. A weekly or bi-weekly change of the nutrient solution is recommended. This will refresh the nutrients available to the plant and reduce the risk of certain pathogens. As the plant grows and begins to uptake a significant amount of the nutrient solution, it may be necessary to top-off the nutrient solution to maintain the proper level in the bucket. This can be done with a half-strength nutrient solution. In other words, dilute the fertilizer twice as much as normal. This ensures that the solution doesn’t become too concentrated between water changes. Without a nutrient monitor a grower will not be able to tell the concentration of nutrients in the water so the half-strength method serves as a safety net.
Another important maintenance item for any DWC system is maintaining a relatively cool temperature around the bucket. Water’s ability to hold dissolved oxygen is directly related to its temperature. As the temperature of water increases, its ability to hold oxygen decreases. For a DWC system, this means if the nutrient solution becomes too warm it will not be able to hold adequate oxygen for the plant’s roots and may even be susceptible to pathogens. Ideally, a DWC nutrient solution should be kept at approximately 68 degrees F. Lastly, litmus papers, or another inexpensive pH test, will allow the gardener to monitor the nutrient solution’s pH. A good pH range would be between 5.5 – 6.2. If necessary, buffers specific to adjusting the pH of a hydroponic system can be purchased at a local indoor garden retailer or online.
Experimenting with hydroponics is a fun and rewarding experience. Greenhouse hobbyists and indoor gardeners can both benefit from the heighten control and speed of growth offered by hydroponic systems. Building a homemade DWC system allows virtually anyone to experience the trials and tribulations of hydroponics. Who knows, maybe your homemade hydroponic system will inspire you to create an entire hydro-garden in your greenhouse. At the very least, you can dazzle your friends and become a little more knowledgeable about the type of horticulture rapidly expanding in popularity: hydroponics.
Eric Hopper resides in Michigan’s beautiful Upper Peninsula where he enjoys gardening and pursuing sustainability. He is a Garden & Greenhouse contributing editor and may be contacted at Ehop@GardenAndGreenhouse.net.