Lessons Learned: Starting A Hydroponic Garden

by Joshua Osuch, CCMGA Master Gardener

Did you know you can grow plants without soil? It's called hydroponics, a method that offers unique advantages over traditional soil gardening. In this article, I'll guide you through the basics of hydroponics and share my experience building a hydroponic garden at the Jana Tompson Research Gardens in Prosper, TX. Whether you're a gardening enthusiast or a curious beginner, this journey into soil-less gardening will showcase how we started and its benefits.

What is hydroponics?
Hydroponics is gardening without soil. Instead of plants getting nutrients from the soil, they get nutrients from the water. Instead of the roots of plants growing in soil the roots are either suspended in water or water is passed over them. If you've ever propagated a cutting in water, you've grown something hydroponically. The principle has been around for a long time. The Aztecs used hydroponic-like methods to create floating gardens, and the hanging gardens of Babylon are thought to have implemented some hydroponic techniques. More recently, the United States Army used it to grow fresh crops in the Pacific during World War 2 on islands with poor soil because it was expensive to have fresh vegetables airlifted. 

Deep water cultures and NFT (Nutrient Film Technique) systems are two of the most common hydroponic systems. Here's what they look like.

Deep Water Culture

In the deep water culture, the roots hang down into the water. The water has nutrients dissolved in it to feed the plants. An aquarium bubbler also aerates the water and adds oxygen to it. Aerogarden, a small commercial countertop garden, is another example of a deep water culture.

NFT (Nutrient Film Technique)

NFT stands for nutrient film technique or nutrient flow technique, depending on who you ask. The idea is the roots grow down into the channels and a thin film of nutrient water flows over them. There's no bubbler in this one because the water gets aerated when it moves around.

These are just two of the most common types of systems. There are many variations and designs, and each system has its advantages. There are commercial versions for growers, small systems for hobbyists (like Aerogarden), and you can make your own. 

Advantages of Hydroponics

The main two advantages of hydroponic gardens are they use less water and space than traditional soil gardens. Hydroponic systems don't need to soak large amounts of soil. They also don't lose water from runoff and loss from evaporation. It takes less water to grow crops like lettuce hydroponically than in soil. Since hydroponics allows plants to be grown in shallow troughs or channels, they take up less space than soil. Hydroponic systems can even be stacked on each other, like the one I built in Prosper.

Prosper Hydroponic Garden
I recently returned to school for a master's in agriculture sciences at Texas A&M-Commerce. I'm currently studying NFT systems and wanted to add one to the Prosper Gardens.

We picked the East side of the tool shed as the location. We picked this site because it would receive sunlight in the morning and shaded from the harsher afternoon sun. 

The first step was to mount some 2x4s to the side of the shed to create a frame to mount the channels on to.

For the channels, I used some downspout gutters and cut them in half. I put holes for the plants about every 8 inches. I 3D printed some caps with the right dimensions to fit snuggly on the ends.

Then, I mounted the channels to the 2x4s at about a 5-degree angle with some utility hooks. I put the channels in a zig-zag pattern so the water would flow back and forth through each channel.

To connect each channel, I used ½ in irrigation tubing.

For the water reservoir, I used a 32-gallon outdoor trash can. The water mustn't be exposed to light; otherwise, algae will grow, turning into a green, slimy mess.

I put an aquarium pump inside the reservoir to the water to the top channel. The water will flow to the top, run through all four channels, and then back into the reservoir.

I used clear, waterproof silicone to make the end caps more waterproof. I wanted to avoid permanently gluing the caps on to clean the inside in case I wanted to replace one. At this point, it was time to plant.

Planting
To germinate the seeds, I used rockwool as the medium. Rockwool is made from melted rock spun into thin fibers with a texture similar to insulation. It absorbs water, holds the seed, and gives the roots structure. It's very similar to a Jiffy pellet, and some growers even use those instead. 

I choose to mostly plant tomatoes. Tomatoes aren't normally planted in NFT systems because they get too tall, and the roots have very little structure. The roots can also clog the channel. The most common crop grown in NFT systems tends to be lettuce, but it was May when I was planting, so it was a little late for lettuce. Part of my research at A&M has been figuring out how to grow tomatoes in NFT systems. There are a lot of hybrid tomatoes that are bred to produce compact plants for window seals and countertops. The variety I picked for this system is called Orange Hat, which produces prolific plants under a foot tall!

I also planted some bush beans and peppers. The bush beans should be relatively short and shouldn't need staking. The peppers are likely too tall for the space, but I figured if I planted them on the bottom row, they might be able to cascade down and be a kind of upside-down pepper.

After a few weeks, they were ready to plant in the NFT system. To hold the rock wool, I used a 1-inch net pot. The lip of the pot hangs on the rim of the holes and allows the roots to grow through. 

The plants were pretty small and still didn't have many roots. To keep them from drying out, I cut the bottom of the pot off so the rockwool would sit lower in the channel and come into contact with the thin stream of water.

Nutrient Solution
Hydroponic nutrients are a lot like fertilizer. They usually come in a liquid or powder form and must be added to the water reservoir in the right concentration. You can mix your own or buy a premade mix. I used the General Hydroponics Maxi Series*. It's a two-part mix. The first part is used for vegetative growth at the beginning of the crop cycle and then the second part is used to promote blooming and fruiting later on. For this reservoir, I needed about 100 grams of the MaxiGro* to start. Each week after planting I premixed some more nutrient solution in a 5-gallon bucket and topped off the reservoir.  

Results So Far

The plants have been growing for about 2 months. The tomatoes have started blooming, and the beans have started to bud. So now I've switched to the MaxiBloom* part of the nutrients We did lose a couple of plants in the beginning because of the heat and more later on due to pests. However, those spots can be replaced or left empty until the next crop cycle. It's been a success so far and we should be able to harvest in a few weeks. I'll post an update then.

Issues
There have been a few bumps in the road. Some issues were solvable, some were detrimental to a few plants, and some were things I wish I had done differently.

Channel height
I used the thicker size of the downspout gutter. I picked this one, thinking it would give the roots more room to grow. However, during the initial planting, the rockwool cube didn't make contact with the water which is why I had to cut the bottoms of the net pots out. By doing this, I could push the rock wool cubes further down so they could stay wet until the plants developed more roots. Most of the plants survived, but I still lost some plants in the Texas heat. I would use a shallow downspout gutter if I did it over again.  

Algae
Algae is almost always present in hydroponics. Anywhere that the nutrient solution is exposed to light algae will likely form. I had a few small leaks in the end caps, eventually developing green algae. The small ones aren't too much of an issue, but I did have a larger leak that nearly covered the end in algae. For the most part, it's just ugly. It won't harm the plants on the outside, so I just wiped the algae off and resealed the end. I will likely remake the end caps on the next cycle.

Pests
This one is the most discouraging. A couple of weeks ago we came out to find the entire top row of tomatoes reduced to stems. We had noticed some of the other tomatoes in the garden beds had had their fruit eaten but we thought it was probably caterpillars. Now, in the hydroponic garden, the entire plant had been eaten. Our best guess right now is rats or tree mice. We haven't been able to find any tomato hornworms, but we've seen plenty of rats in the shed and compost. This might also explain why only the top row was eaten. We've set some traps that might help and I'm considering covering the rest of the tomatoes in a screen or dome. One or two of the top rows might come back, but most of that row will have to be replaced. 

More Resources on Hydroponics
https://aggie-hort.tamu.edu/greenhouse/hydroponics/index.html
https://extension.umn.edu/how/small-scale-hydroponics
https://www.edengreen.com/blog-collection/what-is-hydroponics

Disclaimer:
The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Collin County Master Gardeners or the Texas A&M AgriLife Extension Service is implied.