A Beginner's Guide to Hydroponics

Hydroponically grown lettuces.
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Hydroponics is a form of gardening that uses no soil, but instead grows plants in a solution of nutrients mixed with water. There are many advantages to hydroponic gardening:

  • Plants grow faster. Experts suggest that plants grow at least 20 percent faster in hydroponic systems than they do in soil. 
  • Yields are 20 to 25 percent bigger with hydroponic systems, compared to growing in soil. 
  • No soil is required, which can be a distinct advantage in areas where existing garden soil is poor, or for apartment dwellers where growing in soil is inconvenient. 
  • Hydroponic growing takes less space. Plants don't need to grow extensive root systems to obtain the nutrients they need, so plants can be packed together closely—another advantage for those who must garden indoors. 
  • Water is saved. The reservoirs used in hydroponics are enclosed to prevent evaporation, and the systems are sealed. This allows plants to take up only the water they need. 

The first step to setting up your first hydroponic garden is selecting a system that best fits your needs from among several options. Important factors to consider include: how much space you have, what you want to grow and how much, cost, and how much available time you have to spend maintaining the system.

The three most basic setups recommended for beginners are the wick, water culture, and ebb and flow. All three of these systems can be built from individual components purchased separately, or you can buy a complete setup kit from online retailers or in a hydroponics store.

Wick Systems 

Wick systems are the simplest system mechanically, and the easiest to set up because there are no moving parts. The system contains a reservoir filled with water and nutrients, and above it, there is a container filled with growing medium. The two containers are connected by a wick, which draws the nutrient-filled water up into the growing medium, where it is absorbed by the roots of your plants.

This system is great for learning the basics, but it may not work well with large plants or with water-hungry plants such as lettuce, because the wick cannot supply water fast enough. However, this system works extremely well with micro greens, herbs, and peppers.

Water Culture 

A water culture system is another extremely simple system to set up. In this system, the plants are placed into a styrofoam platform that sits right on top of the reservoir holding the solution of water and nutrients. A bubbler air pump is added to the reservoir to deliver oxygen to the plant roots. This system is ideally suited for water-hungry plants but is not so well suited for more long-lived plants such as tomatoes.

Ebb and Flow

Ebb and flow systems are slightly more complex in design, but they are extremely versatile. This system works by flooding the growing medium with a water/nutrient solution and then draining it back into the reservoir. To do this, the system requires a submersible pump with a timer. One of the greatest advantages of ebb and flow is that you can use the timer to customize your plants’ watering schedule based on the plant size, number of plants, temperature, humidity, etc. You also have the option of potting plants individually for easy customization or filling the entire tray with growing medium and planting directly in the tray.

Choosing What to Grow

Just about any plant can be grown hydroponically, but for beginners, it is best to start small. The best choices are herbs and vegetables that grow quickly, require little maintenance, and do not need a broad range of nutrients. Fast-growing plants are best since they make it easy to assess how well your system works and tweak it as necessary. It can be a real letdown to wait months until harvest time only to find out your system is not working properly. Maintenance-free plants are great for beginners because they allow you to focus on learning about your system—you can move on to more complex vegetables later. If you are growing a variety of plants, it is also important to make sure that they are similar in their nutrient requirements, so that they grow well together.

Lighting

Hydroponic systems are often indoor systems positioned in places where there isn't access to direct sunlight all day long. Most edible plants require at least six hours of sunlight each day, with 12 to 16 hours even better. So unless you have a sunroom or other such space with lots of window exposure, you'll likely need to provide supplemental grow lights. Hydroponic kit systems usually come with the necessary light fixtures, but if you are piecing together your own components, you will need to buy separate lighting fixtures. 

The best lighting for a hydroponics system is HID (High-Intensity Discharge) light fixtures, which can include either HPS (High-Pressure Sodium) or MH (Metal Halide) bulbs. The light from HPS bulbs emits a more orange/red light, which is great for plants in the vegetative growth stage. 

T5 is another type of lighting used in hydroponic grow rooms. It produces a high-output fluorescent light with low heat and low energy consumption. It is ideal for growing plant cuttings and plants with short growth cycles. 

Make sure to put your lighting system on a timer so that the lights come on and go off at the same time each day. 

Room Conditions

It's very important that a hydroponic system is set up in the right conditions. Key elements include relative humidity, temperature, CO2 levels, and air circulation. The ideal humidity for a hydroponic grow room is from 40 to 60 percent relative humidity. Higher humidity levels—especially in rooms with poor air circulation—can lead to powdery mildew and other fungal problems.

Ideal temperatures are between 68 and 70 F. High temperatures may cause plants to become stunted, and if the water temperature gets too high, it may lead to root rot.

Your grow room should also have an ample supply of carbon dioxide (CO2). The best way to ensure this is by making sure the room has a constant flow of air. More advanced hydroponic gardeners may supplement CO2 levels in the room, since the more CO2 available, the faster your plants will grow.

Water Quality

Two factors can affect water's ability to deliver dissolved nutrients to your plants: the level of mineral salts in the water, as measured by PPM; and the pH of the water. "Hard" water that contains a high mineral content will not dissolve nutrients as effectively as water with a lower mineral content, so you may need to filter your water if it is high in mineral content. The ideal pH level for water used in a hydroponic system is between 5.8 and 6.2 (slightly acidic). If your water doesn't meet this level, chemicals can be used to adjust the pH into the ideal range. 

Nutrients

The nutrients/fertilizers used in hydroponic systems are available in both liquid and dry forms and in both organic and synthetic types. Either type can be dissolved into water to create the nutrient mixture required by the hydroponic system. The product you use should include both the main macronutrients—nitrogen, potassium, phosphorus, calcium, and magnesium—as well as the important micronutrients, which include trace amounts of iron, manganese, boron, zinc, copper, molybdenum, and chlorine.

Many nutrient/fertilizers are available that are designed for hydroponic gardening, and you should have good results if you use them according to package directions. But avoid using standard garden fertilizers in a hydroponic system, as their formulas are designed for use in garden soil, not hydroponic systems. 

Choose hydroponic nutrient products that are designed for your specific needs. For example, some are marketed as being best suited for flowering plants, while others are best for promoting vegetative growth, such as the greenery of leafy vegetables. 

Additional Equipment

In addition to the basic hydroponic setup, it's a good idea for beginners to invest in a few additional items. 

You will need meters to test the PPM and pH of the water, as well as the temperature and relative humidity of the room. There are some combination meters available that will test the pH, PPM, and water temperature. You can also purchase meters that measure the temperature and/or the humidity in your grow room.

Depending on your climate, you may need a humidifier or dehumidifier to adjust the relative humidity in the grow room to an optimal level. 

You may want to have some kind of fan or air circulation equipment to improve the air flow in your grow room. Even a simple oscillating fan works well, but as you get more experienced, you may want to invest in a more sophisticated intake-and-exhaust system.

Good Starter Plants

Some plants that work very well for beginners just learning the basics of hydroponic gardening include:

  • Greens such as lettuce, spinach, Swiss chard, and kale
  • Herbs such as basil, parsley, oregano, cilantro and mint
  • Tomatoes
  • Strawberries
  • Hot Peppers

Systems For More Advanced Gardeners

Two more complicated systems are best reserved for hydroponic gardeners who have already learned the basics: the N.F.T. system, and the aeroponic system. 

N.F.T. stands for Nutrient Film Technique. It uses a constant flow of water/nutrient solution that flows constantly in a loop from a reservoir through a growing tray, where plant roots are suspended in air and absorb nutrients as the solution flows by. But if something goes wrong with the pump mechanism, the roots can dry quickly when the flow stops. This system requires a user who can monitor the machinery and fix it quickly if problems arise. 

An aeroponic system is a high-tech method in which plant roots are suspended in air and are misted every few minutes with a water/nutrient solution. It is a highly effective method but one that requires sophisticated pumps and misters. If the equipment has problems, the plant roots on will dry out and die very quickly.