Experimenting with Hydroponic Gardening to Grow Strawberries

STEM STEAM Science Hydroponics

If you’re new to our blog, welcome! We generally talk education topics like STEM, STEAM, science, hands-on learning and maker spaces. But in our spare time, we tinker! And now that Jerry of Brain Brigade has officially retired from teaching…he has MORE spare time! We have been involved in many hydroponic and aquaponics projects in the classroom and maker space, but we have been diving in to various hydroponic methods of growing plants at home.

Last summer I visited Iowa and I noticed a really clever hydroponic tower that was growing lettuce. It was made of PVC pipe that wound around a central tower. I thought that the idea was great. It was compact and allowed for maximum use of growing space for sunlight and circulation of nutrient solution. This winter I began to wonder if something like this could be used to grow strawberries hydroponically. After a bit of research, I decided that I would try to make a tower similar to the one that I has seen.

STEM STEAM Science Hydroponics

This is a photo I took in Iowa of lettuce growing on a hydroponic tower.

As I looked at 4 inch PVC pipe I soon realized that it was very heavy and expensive. I decided to use a lighter plastic pipe that I found at Home Depot. It used the same 90 degree elbows that the heavier pipe used. I first constructed the frame that I would mount it on using 1 ½ inch PVC, elbows and a cross piece at the top to connect all of the frame. I mounted this frame on a wooden base and drilled holes to secure it with bolts. Next, I determined that the PVC pipe surrounding the frame would have to be cut at 25 inches. I bored 3 inch holes in the pipe using a circle drill and mounted the pieces to the frame using plastic straps and bolts. I also purchased a 10 gallon tub for my nutrient solution that sits inside the bottom middle of the frame.STEM STEAM Science Hydroponics

I ordered 50 strawberry plants from Jung’s called Tristar that is ideal for hanging baskets and produces a crop in summer and in fall. I also ordered strawberry nutrient from Amazon. My only concern, is that the pipe connections at the elbows will leak because I have not cemented them with PVC cement. I will use my pump from my hydroponic system in my basement to pump the nutrient solution to the plants. I won’t be using the pump during the summer, so it’s a nice way to utilize my materials all year long! Now. We just need it to get warm around these northern parts!

Maybe you’re thinking, “this is cool…” but aren’t quite ready to take on The Tower quite yet. You could give windowsill hydroponics a try to get your feet wet! It’s an excellent classroom project too.

My Season of Hydroponics

If you’d like to try hydroponics in your maker space or classroom it is a great way to get kids to fabricate, problem solve, make mistakes and experience authentic learning. Many designs for simple hydroponic systems exist online with inexpensive materials. The activity is a perfect STEM activity and integrates math, science and a bit of chemistry into a unit or lesson. You also don’t need a lot of room and can even do it on a windowsill!

Sue and I have also moved from a small condo to a ranch home, so these past three months have been hectic to say the least! We are now in the middle of a full scale remodel. As I type this, carpenters and electricians are working. Jolene and her husband, Phil, also moved. The entire Brain Brigade Team has been shaken up. We’re finally settling back into our Brain Brigade routine and it feels good to be back!

My winter season has been devoted to growing my greens hydroponically. I have also just completed a hydroponic strawberry tower. I can’t wait for spring to get here so I can get  the strawberries growing! I will grow the strawberries outside using my system.

My lettuce is doing great but my spinach is not so great. As you can see by the photo, the spinach is in the foreground and is quite twiggy. I think the pH may be off for the spinach. I’ll do some small adjustments to see if it responds. I began the lettuce and spinach about three weeks before transporting them into my hydroponics system. The floating bed has nutrient solution flowing past the roots. My system is about 24 inches wide and about five feet long. It is made of 2x4s with a bottom of plywood. In this box a pond liner coats the bottom and sides and a hole is bored through the bottom on the plywood at one end. The nutrient solution is pumped up to the box and flows past the roots and down the drain back to the reservoir. I’ve been enjoying lettuce all winter, picked fresh right from my basement. It doesn’t get better than that!

This can be done in a classroom, too! We have highlighted some steps in a series on hydroponics earlier in the blog. Start here to begin learning more!

Aquaponics 101

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I’m assisting Oconomowoc High School with the aquaponics system in their greenhouse. So far we have set up two systems with 50 tilapia in one tank and 50 perch in a second tank. We are facing some challenges with our systems from the heat that is building when the outside temperature reaches 70 degrees or above. Tilapia need a water temperature of about 80 degrees, while perch need a water temperature of about 70 degrees. Our greenhouse reaches over 90 degrees and can see temperatures of 110. Before the weather gets too warm we need to find a way to keep the water cool enough for the fish to survive. Enter Travis. Travis is a second shift custodian at the high school and has significant experience in building aquaponics systems. I sat down with him over lunch the other day and was very impressed by his knowledge and experience. Travis has a high school diploma but has so much knowledge that I thought he had a college degree. Travis has had much hands on experience fabricating and problem solving over 150 aquaponic systems. I asked Travis if he had a degree. His response was that he just had a high school diploma but he picked up a lot of money and expertise doing side aquaponics jobs. He also has sought out many experts and used collaboration to build his knowledge.

Our discussion just reinforced my belief that we need more individuals with the ability to fabricate, and to use their hands to build projects that solve problems. I’m very impressed by his ability to think out of the box. After about an hour of talking, we had a solution to our overheating problem. It struck me that what Travis is doing is just the thing I want my students to do. Think out of the box, collaborate, seek expert advice, problem solve. The world could use more people like Travis!

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.

HydroponicsLED

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

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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.

Adding Tilapia to our High School Classroom Hydroponics System

Last Friday I spent much of my day with five high school students on a field trip to a tilapia farm to pick up the tilapia for our aquaponics project. We purchased 50 tilapia from R&D Fish Farm in Oshkosh, WI. The students spoke with one of the owners and garnered knowledge from an expert who has been raising fish for 12 years. It demonstrated to me how passion can impact learning. Each of these kids gave up their day off of school in order to make this trip. It was an opportunity for them to learn and interact about something they were interested in. Learning in this way fuels a student’s curiosity and give meaning to learning in an authentic way.

picking-up-tilapia

We returned to the high school’s greenhouse and spent another hour acclimating the fish to the temperature and pH of their new tank. From each day forward, these students will need to monitor the pH, temperature, ammonia, nitrites and nitrates in the tank which contains about 175 gallons of water. In addition to monitoring water quality, the fish will need to be fed five to six times per day. A challenge that will face the students in the very near future will be how to hold the water temperature at 80 degrees since the tank is in a greenhouse that can reach temperatures near 100 degrees.

Adding-Tilapia-to-HS-Hydroponics

The second tank that is fish ready will be for perch that we will buy this coming weekend. Perch need to be held in a tank with a water temperature of about 70 degrees. These kids face many challenges in the near future in keeping these fish alive. These challenges will require them to use creativity to come up with solutions. Mistakes will be made but they will learn and adapt to keep this project going. It is a joy as a teacher to work in a meaningful environment where the goal in not just to pass a test.

If you want to try hydroponics but aren’t ready to take the plunge in a large system, download our Windowsill Hydroponics guide. We give you step by step instructions with photos that make it easy to follow and use for personal use, homeschooling, or in your classroom.

Hydroponics 101.2: The Kratky Method

Hydroponics-101

Hydroponics gives your students an opportunity for hands on, authentic learning that is novel, STEM related and gives them a chance to tinker. We’re currently exploring Hydroponics and Aquaponics in a blog series (read Hydroponics 101.1).

Choosing the container that you wish to use for your hydroponic system is crucial. There are two ways that you can approach this. You can either place your plant in a container that has no water and nutrient movement which is Kratky method) or you can re-circulate the water continuously using a pump and aerator. Which method you choose depends on your space and budget.

Hydroponics-for-Classroom-or-Home

With either method, you should begin your plants two to three weeks before transplanting them into your hydroponic system.

In the Kratky method you mix your nutrients in water and fill a container. Next, you prevent light from shining on the solution by duct taping or painting the container, then you cut a hole in the top of the container for your plant basket and you set the plant into the container with some of the roots not immersed in the liquid so they can get oxygen from the air. The upside is that you can grow lettuce and quick maturing plants in about 30 days. The downside is that the nutrient solution will run out or will begin to smell after about a month because no aeration of the solution takes place. This method is simple.

It is very important not to let light hit the solution or algae will begin to grow and use up all of the nutrients meant for your plant. This method is great for windowsill gardens or in small spaces that receive sunlight most of the day.

Hydroponics-101pt2

I’ve noticed some differences with each method. First, root development is much greater in the circulation method and plants do grow a bit larger (see photo comparison). Secondly, the nutrient solution can be used for a longer period of time due to aeration. I have eaten my lettuce from both systems and both salads tasted very good.

Next week I will tackle a circulating system. But before then we’ll be posting on adding fish to our high school aquaponics system!