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Can a hydroponic system be used outdoors?
If you’re wondering if hydroponics can be used outdoors the answer is… absolutely! However, there are things you will need to consider when it comes to determining the best hydroponic system for outdoors. Let us save you some time through our trials. Using various hydroponic methods, we’ve settled on one that we found to be most effective and efficient. Keep reading below and we’ll discuss pitfalls of outdoor hydroponics and how why we feel our chosen method is the best outdoor hydroponic system. We’ve also put together a video for those who are visual learners. In the video titled Outdoor Hydroponic Peppers you can see our system in use. Although we’re using it for peppers, the same technique can be used for many other plants and vegetables such as tomatoes, salad greens, eggplant, and many more.
Thinks to consider when using hydroponics outdoors
Probably the biggest issue you need to consider is rain. If you use a system that requires a reservoir of nutrient solution, such as Dutch buckets, Kratky, Nutrient Film Technique (NFT) or direct water column (DWC), then rain can really be problematic. If rain enters the nutrient reservoir, it will dilute the nutrients and most likely alter the pH of your solution. Using our method, the rain will not harm the system, in fact it will actually help you.
You need to consider how the plants will be supported, especially once they begin flowering and fruiting. Systems like DWC, NFT, and Kratky don’t use a solid medium. Instead, the roots simply dangle into the nutrient solution water. This is fine for low growing plants like lettuce, but for plants that grow tall it will be problematic since there is no way for the plants to anchor their roots.
Our goal is to be as efficient as possible when it comes to water use. Some hydroponic systems recirculate nutrients such as Dutch bucket and NFT. In these systems nutrients are pumped out to the plants, excess drains through, and returns to the reservoir. These methods sound efficient but the reality is that eventually you’re going to need to drain the reservoir and refill with fresh nutrients. This is because the plants will uptake various nutrients (nitrogen, phosphorus, potassium, etc.) from the solution and you can never be sure which ones remain circulating. Our method chosen method does use a nutrient reservoir but never requires the reservoir to be dumped and replenished.
Best outdoor hydroponics system
So, given the potential pitfalls mentioned above I’m sure you wondering… what do we think is the best hydroponics system for outdoors? The short answer is a drip system using an inert grow medium consisting of a 50/50 mix of perlite and coconut coir. Take a look below at the parts list below and then we’ll describe how to set it up with some important detail.
Things you’ll need for this system
Buckets or containers
We’ve found that 5-gallon buckets are sufficient for growing most plants. The roots don’t need much room since they won’t need to go far seeking water and nutrients. We get most of our buckets from restaurants. They are usually happy to get rid of them though I do usually offer them a little cash for them.
You can simply drill some drain holes in the bottom or set them up with a void in the bottom like we did in our Outdoor Hydroponic Pepper video.
You’ll need a large vessel to act as your reservoir for storing your nutrient solution. The reservoir should have a tight-fitting lid that will prevent rainwater from entering.
For this outdoor hydroponic system, you’ll need to set up a drip tubing system. This will consist of a main line, usually 1/2″ tubing, and the smaller 1/4″ tubing and drip emitters. You’ll also need at least one barbed Tee fitting and barbed 90’s and double barbed fittings to connect the 1/4″ tubing.
To get the nutrient water out to the plants you’ll need pump. The size of the pump will vary depending on how many drip tubes on your system but it’s better to use one too big rather than too small. We us this pump purchased from Amazon.
We’ve tried various types of nutrients over the years. We found that the best hydroponic nutrients are made by Masterblend. It’s a 3-part dry powdered kit. They are easy to store in large amounts and have a long shelf life. Simply mix them with water as needed. Be sure and check out our post about the best hydroponic nutrients for vegetables.
When using a drip system, the pump will need to be turned on and off in short intervals. Most household timers only provide 15-minute intervals which is too long for a drip system. We found this interval timer on Amazon that works perfectly for this system.
Solenoid Valve (optional)
If the water level in your nutrient reservoir will be higher than your drip emitters, you’re going to need a solenoid valve to solidly shut off the feed line when the pump stops. If the main feed line is not completely closed then gravity will continue to push water to the dripper. If the water level in the nutrient reservoir will always be lower than the drip emitters then you won’t need a solenoid valve.
How does this outdoor hydroponic system work?
I’ll explain how the system works here and you can take a look at the diagrams below for more clarity. You can also see the system in great detail in the video above.
To start, you’ll need to make a complete loop circling all your buckets with the 1/2″ tubing. This step is very important to ensure equal pressure throughout the system. Do NOT just run a length of tubing that terminates at one end. Another important consideration is that the 1/2″ loop should be 6″ lower than the tops of the buckets. After circling your buckets with the 1/2″ tubing, use a barbed tee between the two ends of the 1/2″ tubing. From the remaining leg of the tee, you’ll run a piece of 1/2″ tubing back to the nutrient reservoir. Connect the 1/2″ tubing to the submersible pump and lower the pump to the bottom of the nutrient reservoir.
Now you’ll need to run pieces of 1/4″ tubing to each bucket for your drippers off the 1/2″ main line that loops around your buckets. It is important that every piece of the 1/4″ tubing is the same length. Figure out the longest piece you’ll need and make all the 1/4″ pieces that length. The 1/4″ tubing is connected to the main line with a 1/4″ double barbed fittings. Terminate each of the 1/4″ drip lines into a bucket and connect a drip emitter to the end of the tubing.
If the water level in the nutrient reservoir will be higher than the 1/2″ main tubing that loops around the buckets then you’ll need to use a solenoid shutoff valve. Otherwise, the weight of the water above the tubing will continue to push water out the drip emitters even after the pump shuts off. Place the solenoid valve after the pump and before the tee.
Now you’ll need to plug the pump and solenoid valve into the interval timer. This may require a little wiring for the solenoid valve. We found that programming the interval pump to turn on the system three times a day for about two minutes each interval to start off. As the plants mature, they’ll require more nutrients per interval. The most we feed our plants is four minutes per interval for a total of 12 minutes per day. If the plants begin to wilt between intervals, you can increase the feed time.