I've been learning about and experimenting with hydroponics for well over a decade now, and I don't think I've ever written about it. I just came across someone expressing interest in hydroponics on Twitter, and I realized that I've done all of this work, but I haven't bothered to share it. It's time to repent and do better.
It all started in the mid-2000s. I honestly probably first heard about hydroponics in the '90s, reading science fiction, but I didn't start taking it seriously until later. (Actually, come to think if it, I did do a very crude but successful experiment growing mint with hydroponics in 2001...) In the mid-2000s, I tried to grow strawberries using hydroponics. It didn't work, mainly due to humidity problems, but I would have had other problems had it gone further. I was talking to a older gentlemen who ran a farm owned by the church I am a member of, and he told me he was successfully growing strawberries using hydroponics. He invited me to come take a look, so I did. He walked me through his setup, explaining the various parts, and I learned a ton. Probably the most important think I learned was that strawberries need more calcium than other crops, which is critical with hydroponics, where the plants only get the nutrients to give them. It turns out tomatoes have a similar need for calcium as well. Anyhow, my main problem was lack of ventilation in my container, allowing humidity to get so high that the plants rotted very shortly after sprouting, but calcium would have been an issue later, had they survived.
My next foray into hydroponics was many years later, after getting married, going through a major move, and getting a Computer Science Bachelor's degree. This time, I had a lot more knowledge. I had studied hydroponics, taken some gardening classes, and done a bit of indoor dirt farming in the mean time, so I had a much better idea of what I was doing. Also, online information on hydroponics had grown substantially. In the 2000s, all I could find was information on how to grow marijuana using hydroponics. By the mid-2010s, I was finding more information on growing lettuce, tomatoes, and other food crops, which was extremely helpful, given that I'm not interested in doing drugs.
I've done two major hydroponics experiments since that failed attempt with strawberries, with the goal of making hydroponics more accessible to normal people. Hydroponics can be intimidating. If you are fairly wealthy, you can buy elaborate in-home systems that are really nice looking but a horrific pain to clean and maintain. I bought a very small version of this by Miracle Grow, and I grew basil for the better part of a year, but it was a bit too small, and the bubbler got clogged regularly and was really hard to clean out reliably. It worked, but it's not a design I would want to use long term. And larger scale versions of that and similar devices look just as hard to clean if not harder. Further, that device cost $50, which may not seem very expensive to the average middle class American but is definitely not worth the cost, when all you are getting from it is a few herbs to season your food. For $5 you could get potting soil, pots, and seeds, and the amount of labor involved would be the same or less. Hydroponics is supposed to be easier. That's what you are paying extra for, after all.
The experiments I did were growing wheat and arugula. I chose arugula due to its similarity to lettuce and the fact that lettuce works very well with hydroponics. I picked wheat, because it is an important staple, and I wanted to see how it worked. The arugula worked better than the wheat, but the issues with the wheat were the result of deliberate laziness just to see how much corner cutting it could tolerate.
The system was very simple. I took a ~2 gallon plastic tote style tub. I installed an overflow drainage system, consisting of a 3/4 inch PVC pipe held in place with a Uniseal bulkhead adapter, adjusted to a height where the water would drain at a quarter of an inch below the level of the media. I ended up having to add a cap to the pipe, arranged to allow water into the top of the pipe without allowing grow media to fall in. For grow media, I used blue fish tank gravel from Walmart. Obviously the color wasn't important. The price was though, as the goal was to produce a system cheap enough for lower income people. I used a 5 gallon paint bucket for the reservoir, and a fish tank pump for the recirculation. You generally don't want the water to be stagnant, as that can allow bacteria to build up on the roots of your plants, and the plants will consume all of the oxygen in the water and then drown. Some hydroponic systems use some form of bubbler, but these require regular cleaning, which can be challenging. This recirculation system allows the water to absorb oxygen from the air as it drains down to the PVC tube and into the bucket. I positioned the grow tub such that the water draining through the tube would fall directly into the bucket, so I wouldn't need any extra tubing to direct it. Also note that the fish pump must be able to lift the water high enough to get it into the grow tub. Fish tank pumps typically have their maximum lift distance listed on the package. Ideally, you will use a pump that can lift the water at least a foot or so higher than what you actually need. In my setup, the pump used a vinyl tube to pump water into the bottom of the tub. I just laid the tube in the bottom of the tub, with the open end at the opposite corner from the drain, to ensure flow through the entire tub, and then I covered it with the fish tank gravel. This system does not require frequent cleaning, but it probably should be cleaned between crops. The plant roots will grow throughout the gravel, and once the plants are harvested, the roots will begin to rot. This honestly isn't a huge issue, and you can probably get away with two crops between cleanings, but cleaning is necessary. (Note that with the Miracle Grow thing, more frequent cleaning is necessary to keep the bubbler unclogged.)
For lighting, I used Walmart plant lights and a bit of natural light from a nearby window. For indoor growing, plant lights are pretty important. Not all crops need a ton of light, but most need more than they can get from a window. I put the lights on a wall plug timer, on a schedule that gave the plants around 16 hours of light a day. Most plants don't need that much, and nearly all plants need dark nights, but few plants strictly need more than 6 hours of darkness at night, and most will benefit from longer daylight. This is why plants in Alaska can handle such a short growing season. They grow much faster, because they are getting more light. Applying this to hydroponics can get similarly impressive growth rates.
Plants also need nutrients. In the interest of keeping things cheap and simple, I decided to use orchid fertilizer crystals. These dissolve easily in water and contain the critical macronutrients and a decent range of micronutrients for plants. Obviously they are balanced for orchids, so I wanted to see how they would work for other plants. Note that this would probably not work for strawberries or tomatoes without an additional calcium supplement, and other plants may have their own special needs.
For the arugula, I planted the seeds at the depth recommended on the seed pack, making sure they were in a location where they would stay wet. They sprouted easily and grew rapidly. I let the arugula grow the maturity, which might have been a mistake. It turns out that there's a reason most salad packs use baby arugula. Mature it is quite spicy. I blended it up with some ranch, and it made an excellent dressing, with the kick diluted enough to have just the right amount of spice.
The wheat turned out very interesting. I wanted to test to see how it would handle if it was planted in the laziest manner possible, because people have a habit not reading instructions. So, I just sprinkled the seeds (just wheat grains bought at the grocery store) on top of the media. I was actually surprised at how well this worked. Most of the grains eventually settled down into the water and sprouted. The lack of depth was a serious problem with stability though. The roots alone aren't strong enough to hold up the tall wheat plants, so they fell over. Once they got dense enough, I was able to stand most of them up, by leaning them together, but I would have to periodically fix them to keep them even close to upright, and the ones around the edges just wouldn't stay. You could probably get away with this planting strategy with some plants, but wheat isn't one of them. Despite this though, they grew somewhat well. The main problem I had was small grains. Probably 80% of the grains were very small and shriveled. I was able to get some good grains, but it wasn't a good harvest. Given that I was using hydroponics, lack of water was definitely not the problem. If I recall, I was using six 60 watt grow bulbs, for a total of 360 watts, so the problem probably wasn't poor lighting either. All that leaves in nutrition. It's possible that this industrially farmed wheat needed the massive quantities of fertilizer used in industrial farming. I didn't try to calculate nutritional needs or keep the fertilizer balance perfect (again, this would be a ton of work for normal people, and I was trying to develop a process that was easy), so it's very likely nutritional balance was an issue. I want to rerun this experiment, using more fertilizer, to see what happens, but just don't have the space or time right now.
What would I do differently? There's no point in doing experiments if we don't learn from them. There are a few things I would do differently. First, I would use a plastic restaurant tub, instead of a plastic tote. At one point between experiments, the original tote fell off of its shelf, and it shattered. The mess was absolutely epic, and it was a horrible clean up job. I never want to deal with that again. Restaurant tubs are made of more flexible, softer plastic. They are also pretty cheap and significantly larger, including deeper. This would give more room for deeper water without risking overfilling the container. This is just a better strategy in general. In future runs, I'm going to keep better track of fertilizer amounts, and I would like to do some testing with more or less fertilizer. What I really need is a space where I can have 3 or 4 of these setups running at the same time, so I can do some controlled experiments. Obviously I want to do another run with the wheat, planting it deeper. It might also be good to try other kinds of media. The main problem though, is that purpose made hydroponic media tends to be quite expensive and is not reusable. My friend with the strawberries used coconut husk, but you can't clean and reuse that. Puffed clay pellets are also common, but roots grow into them, requiring disposal after a few runs. Both of these are also expensive. Cheaper options are perlite and vermiculite, but both of these are very porous and roots will grow into them as well. The fish tank gravel worked quite well. Sand might work for certain crops. Carrots are sometimes grown in sand in more traditional gardening, so sand would probably work for carrots. Something between the size of fish tank gravel and sand would probably be ideal, but the smaller your media, the harder it becomes to wash roots out without washing away the media itself. Fish tank gravel seems to be about the smallest you can get while remaining 100% reusable. Cleaning is still a bit of a chore, but if you have a place you can carry the (heavy, with all of that gravel...) container and fill it with water to overflowing, you can loosen up the roots with your fingers, and they will generally float out of the overflowing container after that. It's honestly not bad, but I would love to find a solution that is even less work than this to maintain. (I've considered trying to dissolve the roots with muriatic acid, which is literally just diluted hydrochloric acid, but this is a bit hazardous, and if it isn't rinsed completely it could kill the next batch of plants, so probably not a great idea.)
Anyhow, that's where things are right now. This is highly experimental, but I did have solid success with arugula, and lettuce family plants in general tend to be very forgiving with hydroponics. I'm not currently running any experiments due to lack of space, but I hope to rectify that soon and get some larger scale experiments going. I'll try to remember to post as I go once I get to that point, instead of waiting years so that I forget details that are probably important (like how much fertilizer I used). To be fair, these were very much preliminary experiments, but that's no excuse for laziness and procrastination.
On a side note, funding would help. If you can't afford to help or just don't want to, please don't feel like I'm pressuring you. If you are legitimately interested in this stuff or other things I've discussed here though, and you can afford to provide even a little bit, it would really help. You can contribute here: https://www.patreon.com/techniumadeptus If you only want to make a one-time donation, and you happen to use the Brave browser, you can donate directly through the browser on YouTube (sorry, no videos yet; maybe once I get enough funding to have things to make videos about...) or Github (you can see some of my open source work there, if you need evidence that I'm serious about that).
Note that I'm not doing any of this as a for-profit thing (beyond needing an income to support myself and my family). I won't promise not to develop any of this into a commercial product (especially when that is often the best way to maximize availability and minimize cost), but I do promise to work under an open source ideology. Anything I develop under this is free for the public to use, and I'll publish whatever information I have, including any plans and designs I develop, that is paid for and developed through this, under an open source license. So, in contributing, you aren't supporting a corporate endeavor, but rather you are supporting an independent inventor who want to develop products and ideas that benefit people. A major part of this is making my ideas freely usable by anyone who wants to use them, whether I decide to make them commercial or not.
