Hydroponic gardening has exploded in popularity in the last couple of decades. One reason for that massive growth is that you can adapt your hydroponic setup to fit almost any situation- whether indoors or outdoors.
Outdoor hydroponics gardens come in various forms, with the best systems being the Kratky method, ebb and flow, and drip systems. Outdoor hydroponic gardening takes advantage of natural sunlight and wind, so it has a lower electrical expense compared to indoor systems. However, maintaining your hydroponics outside is more labor-intensive in some respects.
In this article, you’ll learn more about the differences between running a hydroponic indoors vs outdoors, and tips for getting the best harvest from your outdoor system. You’ll also read about hydroponic techniques and plants that work well in an outdoor setting.
Let’s get started!
Outdoor Hydroponics vs Indoor Hydroponics
All hydroponic systems bypass the mess and challenges of soil-based growing by feeding your plants nutrient-rich water and ensuring plenty of oxygen exposure. This typically results in explosive growth and bountiful harvests, all while using less water than traditional gardening or farming.
Indoor hydroponic gardening is a method that uses artificial lighting and sometimes fan-based air circulation to create an environment for growing plants inside. Commercial growers often use this method to produce large amounts of crops quickly. Indoor hydroponic gardens are ideal for people who lack outdoor space or just prefer to have tighter control over their plants’ growing conditions.
In contrast, outdoor hydroponic gardening does not require any artificial light sources or air circulation. Instead, it relies on natural sunlight to provide energy for photosynthesis and the passing breezes for air movement. Because it requires less electricity to run, an outdoor hydroponic system often costs less to run over the long term.
However, when you set up your hydroponics outside, you lose some of the control and sterility that indoor growing provides, and the risk of pest attacks is higher. Also, setting up an outdoor system may have a higher initial investment since you’ll need to use tougher materials that can better withstand the elements.
Pros and Cons of an Outdoor Hydroponics System
7 Tips for a Successful Outdoor Hydroponic Garden
To ensure success with outdoor hydroponic gardening, keep in mind the following tips.
1. Choose a Sunny Location
Plants that produce fruit (tomatoes, cucumbers, etc) or flowers need plenty of sunshine to generate the energy they need to produce their harvest. And even leaf crops, like lettuce, greens and herbs, also need at least a few hours of sunlight each day to grow at their best pace.
Select a location that receives at least six hours of direct sunlight daily so your plants will grow properly. If needed, consider cutting back some overhanging tree branches or trimming tall hedges down a bit to get more light exposure for your garden.
2. Ensure Good Airflow
Stagnant air and overcrowded plants are a surefire recipe for disease and pest infestation. So make sure the area you choose for your outdoor hydroponic system has good airflow- not tucked away in a corner or surrounded by a dense hedge.
Instead, choose a site that’s open to the breeze on all sides. And an open patch of ground probably gets the best sun exposure as well, so you’re hitting two birds with one stone.
Also, don’t give in to the temptation to pack in as many plants as possible. Having lots of plants may seem like the best way to ensure a good harvest, but in reality, if your plants have to compete too much for water, air or nutrients, your garden won’t be as productive as you envision.
3. Be Alert for Pests
Having your hydroponics outside, unfortunately, attracts pests. Pests can cause significant damage to your crops if they aren’t dealt with promptly. As a result, it is crucial to check your garden for them routinely.
If you spot any pests, take action right away. Pests almost never disappear on their own, so don’t hesitate to apply the appropriate treatment as soon as you identify a problem.
4. Maintain Proper Water Temperature
All hydroponic systems, whether indoors or outdoors, function best with water temperatures between 68 and 72 degrees Fahrenheit. And that can be hard to maintain in backyard hydroponics when you’ve got daytime temperatures in the 80’s or above for any extended time.
Melody Estes, Landscape Design Gardening Supervisor and consultant at The Project Girl, says, “Temperature is the biggest concern when running an outdoor hydroponics system. The temperature can change drastically throughout the day, so it’s important to monitor it closely and make adjustments if necessary.”
Water that’s too warm will kill plants more quickly than water that’s a bit too chilly. Typically, a water temp of 80 degrees F is the true danger zone that plants just can’t survive.
So keeping the nutrient solution in your outdoor hydroponic garden at the right temp is critical. Here’s what you can do to keep your plants cool and healthy:
- Ensure your reservoir is away from direct sunlight, preferably in a shaded area. You may want to consider building a small shade structure for your reservoir.
- Use a light-colored material to build your reservoir to deflect the sun’s rays. You could also paint the outside of a darker reservoir white.
- Fill your reservoir with cool water and apply a layer of insulation to maintain the temperature. Partially burying the reservoir can also act as a form of insulation.
- Use a tank chiller or add frozen water bottles to keep the water cooler.
If you’re interested in trying winter growing, use an aquarium heater to keep your nutrient solution at the proper temperature.
5. Maintain Lower Electrical Conductivity
Hydroponic growing relies on liquid fertilizers to create the nutrient solution. When a mineral fertilizer such as potassium nitrate is dissolved in water, it separates into two ions. One possesses a positive charge known as a cation. The second has a negative charge and is known as an anion.
Using an electrical conductivity (EC) meter you can determine the strength of fertilizer solutions. The higher the ionic concentration, the greater the EC. You can therefore use EC to measure the strength of hydroponic fertilizer solutions.
It’s crucial to check the EC level of your hydroponic garden since high nutrient levels will prevent the plants from absorbing water. In contrast, low nutrient levels allow the plant to absorb water without delivering the necessary nutrients to enhance development.
Different crops have different EC requirements, so it’s critical to know the safe range for your specific plants. Oklahoma State University provides a helpful chart listing some common crops and their EC range.
In your outdoor hydroponic garden, aim to keep your plants on the lower end of the recommended range for the best growth.
This video from ZipGrow does a great job of explaining EC and some basic troubleshooting techniques:
6. Prevent Overheating in Hot Weather
Weather is another variable that can affect your plants in a backyard hydroponics system. While most fruiting and flowering plants need lots of sun, there is a danger of too much of a good thing.
You can’t help the weather, but you can take some steps to prevent your plants from suffering heat-related damage:
- Put up shade cloth or build a shade structure over your plants to protect the foliage/fruits from harsh sun exposure, particularly the midday rays.
- Choose plants that are suited to your local climate. For example, don’t try to grow plants that require partial shade when your region is known for hot, harsh summers.
7. Perform Regular System Maintenance
In some ways, it’s easier to care for an outdoor hydroponic garden, like no need for artificial light or fans to circulate air. But setting up hydroponics outside also means you lose the stable, protective indoor environment, and there are more variables to consider for your system maintenance.
Once a growing system is up and going, a few tasks must be completed every day or every other day to cultivate hydroponic plants properly:
- Make sure the system is functioning correctly. Be alert for damage to the system from weathering or animals- inspect junctures closely to ensure tight connections and no obstructions.
- Check the water level in your system frequently- you may lose more water to evaporation in an outdoor system, so be prepared to top off your system as needed.
- Check on your plants frequently to observe how they’re doing.
- Remove any dead plant matter right away.
- Not all bugs are bad- learn to discern friendly garden insects from destructive pests. Encourage the presence of dragonflies, spiders, and “daddy long legs” (these are just a few of your garden friends!) as they consume undesirable insects.
What Are the Best Outdoor Hydroponic Systems?
There are many types of hydroponic gardening systems available today, and many can be adapted to outdoor conditions if you’re willing to put in the time, effort and creativity.
The best outdoor hydroponic systems provide the most efficient way to grow healthy crops with minimal maintenance. And of course, the system you choose also depends on your needs and the available space and resources.
Below, we have outlined the systems that we believe are the best for outdoor hydroponics systems.
The Kratky technique is a passive hydroponic system, meaning that it doesn’t need pumps or other mechanical equipment to deliver water, nutrients and oxygen to your plants. Instead, the Kratky method uses a reservoir filled with a nutrient solution, with holes cut into the top of the reservoir to hold plants. The plant’s roots grow downward, drawing nutrients from the solution.
As the plants grow and absorb the solution, the water in the reservoir decreases. This leads to the plant’s roots gradually getting higher oxygen exposure, resulting in boosted growth with no extra effort on your part.
Since Kratky is an entirely passive system, it is ideal for a hydroponics system in your backyard. There is no need for pumps or wick, and no energy is used. In contrast to other systems, growers also don’t need to alter the reservoir’s nutrients frequently. Therefore, Kratky is a system that requires little upkeep and after you set it up, the system can function for several weeks.
The Kratky method works best for crops that mature quickly and produce mainly leaf harvests. We put together a post on which crops thrive in a Kratky tank, so check it out to get more ideas!
Ebb and Flow
An ebb and flow hydroponic system, also called “flood and drain,” uses a lower reservoir and upper grow bed. It is an active system, meaning that it requires electricity to power the system components.
The reservoir holds the nutrient solution, and a pump intermittently floods the grow bed. When the solution reaches a certain depth, the pump turns off and a bell siphon allows the excess solution to drain back into the reservoir to be used again on the next flood cycle.
One of the main draws of the ebb and flow method is that it achieves an ideal balance of oxygen exposure for your plants’ roots and easy nutrient uptake. It’s easy to set up and requires minimal water and nutrient inputs.
The drip system is another popular active hydroponic system, and it’s a little different in that the nutrient solution is supplied from overhead instead of underneath the plants.
In a drip system, your plants grow in an upper grow bed, either in one large bed or a series of smaller ones. A pipe or tube irrigation system has openings at each plant, and the nutrient solution flows to individual plants. The roots absorb the solution as gravity carries it downward, and any excess solution gets collected in a reservoir to be re-used on the next drip cycle.
A drip hydroponic system greatly reduces water and fertilizer solution costs while providing optimal plant growth conditions.
Another benefit to a drip system is that you can start plants from seed in the system itself. Since most other hydroponic techniques use a bottom feed, they require seedlings with established roots. But given that a drip system uses an overhead supply, your seeds can germinate, develop their roots and live their entire life in the same system.
One drawback is that a drip system tends to be more expensive than the other two methods. As a result, many individuals choose to employ the Kratky or ebb and flow approach instead.
Which Hydroponic Systems to Avoid Using Outdoors
While there are plenty of growers using any and all hydroponic systems outside, there are a couple of systems that are more difficult to manage in an outdoor setting. That’s mainly due to the unavoidable temperature fluctuations many regions experience seasonally.
Unless you live in a temperate climate year-round or want to take on a bigger challenge, you may want to leave these systems indoors:
Deep Water Culture (DWC)
Using an oxygenated nutrient-rich water solution for the plants is at the heart of DWC. The roots are entirely immersed, hence the name “Deep Water” Culture. This contrasts with other systems where the roots are suspended in the air and water is added at set times.
This type of hydroponic system requires a lot of maintenance. For example, you’ll have to clean out the container every few days. If you don’t do this, the plants could develop root rot, a potentially fatal disease. Also, due to the nature of this hydroponics system, it isn’t easy to maintain the proper water temperature, especially outside.
Nutrient Film Technique
The nutrient film technique (NFT) uses a shallow, elongated grow bed, usually built with a slight slope to one side. A water pump supplies an intermittent or continuous flow of nutrient solution over the plant’s root tips. Since the water level is so shallow, it forms a “film,” hence the technique’s name.
NFT is an active system that uses a pump to circulate water, but the sloped grow beds also take advantage of gravity to drain excess solution back into the reservoir.
This method is a great technique with lots of benefits, but it usually functions best in an indoor environment. As with the DWC technique, NFT can also become problematic with fluctuating temperatures.
Best Plants for an Outdoor Hydroponic System
Plants with a smaller root system are usually the most successful when it comes to hydroponics, and they also allow you to grow more plants in a limited space.
Plants that do well in hydroponics systems:
And this list just scratches the surface. You can grow almost anything hydroponically if you’re willing to put in a little more time and effort.
However, there are a few plants that require specialized systems and care methods to grow hydroponically. While it’s possible it grow these crops, you may want to hold off until you’ve gained more experience with hydroponics:
- Potatoes and Sweet Potatoes
- Vining plants (sweet peas)
- Large Root Vegetables (turnips and rutabaga)
- Bush types (squash and zucchini)
Frequently Asked Questions about Outdoor Hydroponics
Hydroponics is frequently thought of as indoor gardening, and it is indeed a perfect way to convert indoor spaces into thriving, productive gardens. But outdoor hydroponics has a lot to offer as well, and it usually produces much better, faster results than making that outdoor space into an in-ground garden.
But before you jump right into setting up your first backyard hydroponics system, make sure you research which system will be best for you and that you understand the tasks that come with it.
Then, watch that hydroponic system become the garden you’ve seen in your dreams!
Do you still have questions about outdoor hydroponics? Have you set up your own system and have some knowledge to share? We learn best from one another, and your thoughts may be just what someone else needs to hear. So please leave a comment!