An Experiment in Growing Hydroponic Tomatoes

GrowingHydroponicTomatoes

Gardening has been a hobby of mine for a very long time. In fact before moving into the condo that I currently live in, we lived on 5 acres and I had a gigantic garden and greenhouse. Gardening can be a great maker experiment. From planting in the ground to raised gardens to pots. Choosing the seeds or plants. Watering systems. Tilling methods. It requires using the engineering design principle. Trial and error. Taking a risk. And then if your garden fruits, you have to determine what to do with the harvest. Crack open your cookbook and pull out those jars, you can learn to can your produce. Or freeze it. Or use it up. Or sell it. Or give it away. Or trade it. Moving into the condo required me to downsize my quarter acre garden and get creative. At the same time that I moved, I had been dabbling in hydroponics in our Maker Space at school. I got excited about doing hydroponic gardening at home and that’s what I did this past winter.

With the weather warming, it is almost time to shut down the hydroponic operation in my basement and focus on planting outdoors. One experiment I’m trying is to compare the growth of tomatoes grown hydroponically with those planted in soil. I began the tomato seeds on March first and have since transplanted them once. Three tomatoes were transplanted in deli cups and a fourth was transplanted in a five gallon bucket with perlite as the growing medium.

I have tried to treat the four plants the same with keeping them outside and giving them water. The difference is that the plant in the five gallon bucket receives a nutrient solution 4-5 times daily poured from a reservoir. As the unused nutrient solution flows down through the perlite it returns to the reservoir through a drain so it can be re-poured at a later time.

I expected that the hydroponic plant would do much better than the plants in soil, but this has not happened. As of this morning, the plants in soil are about two times as large as the plant in the bucket. In about a week, I will transplant the soil plants to the outside. My guess is that they will experience some transplant “shock” and their growth will be slowed.

I am also wondering if the nutrient solution should be tweaked for the hydroponic tomato. I used the same formula that I used for growing lettuce in my basement under lights during the winter. I believe that because tomatoes need green growth as well as fruiting growth that it may be necessary to add more phosphorus. The nutrient balance I am using is 19.5 – 18 – 38 so all of the nutrients are there. I am also wondering if the concentration is correct.

I just got an E.C. meter to test the conductivity so I will need to learn how to use that. I’ll keep you posted but for now, more study is needed. See what I mean about making and gardening as a perfect maker experience!

Hydroponics 101.4: Light Requirements

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I’ve been growing plants using hydroponics for a few years now, both at home and in the classroom. For the first several years of doing hydroponics and aquaponics systems, I used a bank of T-5 fluorescent bulbs and they worked okay. But in this last planting, which I have set up in my basement, I purchased a bank of LED lights. I am passionately green and I read that LEDs are much more energy efficient and last much longer than any other type of bulb. I also read that LEDs can be tailored to provide the exact wavelengths of light for plants and flowers. You see, plants love light from the blue and red ends of the spectrum. While fluorescents provide some of that light, much of a fluorescent’s light is white and that is a waste of energy because plants use very little white light.


We’re currently in a series exploring Hydroponics {read our previous entries 101.1, 101.2, 101.3}.


The bank of LEDs was about $275 dollars. This was comparable to the cost of a T-5 bank of fluorescent bulbs, but I was astounded at the small size of the LED bank!

T5-and-LED-Light

I was blown away by the light though! What the LED bank lacked in size, it more than made up for in intensity. The instructions stated that the light should be hung at least 24 inches above the plants. I was able to hang it at about 22 inches. I was stunned that the light covered an area of about 2×4 feet where the plants were located. This from a bank of lights that is five inches wide and 18 inches long! My fluorescent bank was 22 inches wide and 46 inches long.

I left the light on while I worked in the basement. After about 15 minutes I started to see everything in a green aura. The intensity and wavelength of the light was affecting my vision. I decided to turn off the light and construct an enclosure around my plants that had Mylar reflective material on the sides to reflect the light back on to the plants.

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My plants are now bathed in blue and red light and are growing wonderfully.

Oh, and my vision is back to normal.

Hydroponics 101.3: The Circulation Method

Hydroponics-101

Picking up where we left off in our Hydroponics series… The circulation method of hydroponics is ideal for you if you have a few more dollars to spend (as compared to the more limited Kratky Method) and you would like your students to make a hydroponic system in the classroom. It is a great way to integrate the engineering design process and STEM into your curriculum as well as offer authentic learning to your class. It also offers you a way of integrating principles of chemistry and physics into your curriculum.


 

We’re currently in a series exploring Hydroponics and Aquaponics.
{Read the previous entries here Hydroponics 101.1 and Hydroponics 101.2}


 

In the circulation method, you need to provide a nutrient trough for the plants to bathe their roots in. This can be done in many ways. Two methods that I have worked with are a floating bed system and a rail system. With both systems I had great success.

Circulation-Method1

With the floating bed system, have your students construct a sturdy box of 2×4 lumber about two feet wide and four feet long. Attach a piece of plywood on the bottom and drill a hole for a bulkhead attachment to allow water to drain from the bed to a reservoir below the bed. Next, place a rubber pond liner inside the box and cut a small hole in the liner to match up with the hole you drilled earlier. Screw down the bulkhead and tighten it so that water will not leak out of the box. Now cut 2 inch holes into a piece of ½ inch thick pink Styrofoam insulation board. I used a 2 inch circular hole saw in a drill bit and ran the drill BACKWARDS so that the Styrofoam was not shredded.

Circulation-Method2

Now you are ready to fill the reservoir with water. I use a large plastic container (about 25 gallons) with a small aquaponics pump on the bottom and a hose running up to my growing bed. I fill the reservoir with water, add my nutrient solution, turn on the pump and circulate the water. Monitor the water height in the bed so that when you add your plant cups their roots are touching the water. I also would recommend you add a PVC pipe below by attaching it to the bulkhead with a PVC fitting so that water flows back to the reservoir.

Next we’ll explore light requirements, planting and monitoring your system.

Taking Creativity Risks in the Classroom {and at home}

HydroponicsLED

Wow! I took a risk and upgraded my basement hydroponics yesterday with an LED plant light. It was $280 for a light that covers a 2×4 foot area. Today I will add a Mylar reflecting foil to the sides so it maximizes the light hitting the plants. It was quite a shock because the light is mostly blue and red-very difficult on the eyes. In fact, after working around the light for 5 minutes everything seemed to have a green.

My basement is now illuminated with an eerie purplish glow. It kind of reminds me of the story “A Wrinkle in Time” when It was trying to hypnotize Meg and Charles Wallace with a throbbing light. I wonder what my neighbors are thinking.

Some of the things I do are really “out of the box” and it is difficult for some of my neighbors because we live in a condo. Residents in a condo are not exactly amenable to strange ideas, like when I grew hydroponic broccoli on my back porch last summer. Change and new ideas are hard to adjust to for some people. But to me that is the excitement of living. To try new things, to experiment, to continuously learn. Isn’t that what we want in our classrooms? Doesn’t curiosity drive learning?

We also need to be willing to make mistakes and learn from them. We have to view failure not as the end, but a brief pause in learning. Somehow our children get the idea that failure is bad, maybe it’s that we put too much emphasis on grades.

We need to grow curiosity, take risks, encourage children to try new things, to experiment. I believe if you, as a classroom teacher, cultivate these traits, your children will begin to emulate you.

I will keep you updated on my hydroponic garden and I will turn off the LED light before I work on my plants!