Urban Farming

Part II: My Hydroponics Setup and Experience

We left off on a sad note in my last post. About 1/3 of my seedlings had fallen to blight due to a series of unfortunate events that could have been avoided had proper precaution been taken. The picture below is a reminder of the root cause. An exposed root system to both light and air allowed for fungal growth to occur and propagate.

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Exposed roots and water allowed for fungal growth to occur.

So what did this look like? Well many of the plants that suffered from fungal growth had very slimy roots and it often turned black or brown–thus the roots died. Usually in hydroponics (depending on your plant), white roots are attributed to a healthy plant. Once the roots begin to decay they can turn black or brown and they also give off a rather putrid smell. You can see in the photo below the faint outlines of the slime along the dark roots of these sprouts.

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Slime on roots

Now this is also evident on the upper part of the plant. Many of the leaves will wilt or the stems will deflate in tugor once fungal or bacteria growth occurs along the roots.

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Wilting leaves

Other signs may be along the tips of the leaves where they begin to turn brown or splotchy.

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Leaf tip browning

Other characteristics you may notice are stunted plant growth, yellowing of the leaves, etc. Now you can use hydrogen peroxide or other reservoir cleaning agents, but sometimes it’s not worth it to save a few of the affected seedling because now they are prone to stunting or cannot resist other form of blight. Even though I did try to save as many as possible, some of the root networks were completely decimated when I tried to wash the slime off or some of the plants just died a few days later because it was too late.

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RIP first hydroponics batch test

In order to save the other 2/3s of plants, drastic measures were taken. The glass jars were scrapped in favor of downspouts I purchased from Home Depot. They came in 12 foot sections and were cut down to almost 4″ sections in the store. Each of the downspouts had a 2″ hole drilled around 6″ apart on center. This gave me a total of 6 reservoirs with the potential to grow around 7 plants per reservoir.

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Downspouts

I purchased a few 45 degree attachments to place on either end of the downspouts to avoid any water spillage and to allow for refilling the reservoir. Unfortunately this wasn’t a very clean process. Downspouts and their attachments aren’t design to be watertight because their main purpose is to direct the flow of water outside, so spilling some water here and there isn’t to problematic. Thus I had problems with leaking reservoirs because it contained too much sitting water. Maybe it could have also been due to the silicone adhesive I used. The other problematic aspect was they were too large for the enclosure once the attachments were added. So I knocked out a side wall to allow for more space.

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Three downspouts per shelf

There were three downspouts placed per shelf. One end of the downspout and its attachment was taped closed while the other was allowed to remain open. The best sprouts that were almost of the same size were placed in the reservoirs. The larger sprouts were placed in containers with a solid growing medium (coco coir and perlite) to reduce competition in the reservoir system and also to see if the solid growing medium was better for these vine plants (cucumber and pumpkin).

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Overall downspout layout

It was evident that the plants towards the center of the grow lights grew the best whereas the plants along the ends of the downspouts became very leggy and were stunted in foliage and leaf growth. This was best illustrated by my bottom shelf of downspouts.

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Bottom shelf center

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Bottom shelf left corner

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Bottom shelf right corner

It’s also interesting to note that my upper shelf did not produce as much foliage as the lower shelf did. In fact even a few of the plants at the center of my lights seemed to be stunted. This could have been due to the competition for nutrients with its neighbors.

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Upper shelf left corner

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Upper shelf right corner

Eventually I added a fan that blows air into the chamber every 5 minutes for a minute or two. My lights also cycled on every 12 hours. My shelving unit was moved towards the window in order to expose the backside to natural light. I controlled these active processes with an rpi. I refilled my reservoirs every week depending on plant uptake, which increased as the plants became ready for harvest.

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Full chamber plant growth

While there were area that were stunted in growth, a lot of my plants grew to quite large sizes. I didn’t effectively prune these plants and thus they grew wild.

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Wild plant growth

I had about three cycles of plant growth in this chamber. This bowl of salad was taken from my first harvest.

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First harvest salad

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First harvest salad

This bowl of salad was taken from the second harvest of the entire first batch.

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Total harvest

Now I did have some problems with leaf burn because they plants were too close to the lights and also my watering of the reservoir became less consistent over time. My third batch of growth became a bit of a nightmare (more on that later) and thus I took apart my hydroponics to redo the entire set up. Overall there are many things I can improve, but I found this to be a rewarding learning experience. In the next post I’ll talk about my third batch hydroponics and my new set up. Happy planting!

Author

smundon@bu.edu

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