Fresh greens all year long

This is one of my sideprojects I’ve been working on mainly during 2016 and 2017. It stems from two connected facts. First is that one of my biggest hobbies is food. Second is that it’s hard to prepare tasty meals without fine ingredients. I do not mean fancy. Rather fresh and full of taste, preferably seasonal and local.

This is even more obvious outside of green season say between mid-October til the beginning of May. Grocery stores offer some kind of veg and fruit, but usually quite blend and tasteless. Not mentioning their carbon footprint. Or is it too much not to expect apples from South America in Central Europe? This easily can get to some rant about globalization, multinational corporations etc. I do not want to get there. After all, it’s the people’s wallets that drive the economy.

I wanted to create a prototype of small self-supplying system, that would partially satisfy my needs for fresh veggies outside of main season. It was built using artificial LED lights, DIY aeroponics system and a bit of tooling for monitoring.

Continuous herbs harvest - clicking on image leads you to three months time-lapse video Continuous herbs harvest - clicking on image leads you to three months time-lapse video

Feeding evergrowing urban areas

There’s another challenging idea related to this project. Thanks to urbanization, more and more people are moving from rural areas to cities.

How to feed them? And how to do that sustainably given the fact that our planet has limited resources? How about water consumption that is going to be a big issue soon? Actually it is even as of writing this article. Agricultural concepts from past are no longer enough for feeding growing population of people.

Contemporary foodchains also heavily rely on usage of transportation from countries that have better conditions for growing greens. Especially during winter, only several lucky countries have the chance to grow greens for their own consumption (and for export then as well). It would be nice to reduce this need of environmentally harmful transportation by planting greens closer to their consumers. It might not be applicable to all plants, but hey, something is better than nothing.

Main idea

All right, so here comes the thing. Main concept was to create low-pressure aeroponics growing system to produce some greens for personal use. Using high quality LED lights as a source of light for plants in the winter season. When deciding what material to use for box construction, I was strongly emphasizing potential scalability. Currently we’re talking only about scaling horizontally. Using more solid construction, vertical scalability is achievable as well. My idea was to create easily replicable box with base of one square meter roughly 1,5m tall.

Growing box with lights on Growing box with lights on

What’s nice about these systems is when designed properly, they are easy to maintain. Depending on your reservoir capacity, it shouldn’t be a problem to go for a week long vacation without plants having to suffer. I did and it was nice to see the progress plants have made during that time :). Also there’s a huge potential for automation of temperature control, humidity, nutrient solution parameters etc. I have not done far with those because those weren’t the main aim of this prototype. Maintenance automation will bring this prototype to a different level though.

Majority of used equipment was bought in regular hobby markets with two exceptions. Those are Raspberry PI with USB camera and custom made LED light by my friend Roman Pavelka (thanks for that!).

Used components

There are still two main questions to answer to justify used technology.

Why aeroponics?

The main reason was that I already had prior experience with aeroponics and that experience was quite joyful. With reservoir big enough so it’s possible to stabilize pH and EC values. Then aeroponics growing consists of following several rules, maintaining top notch tidiness and being punctual with maintenance. Second big reason is more of a strategic / ecological one. Big advantage of aeroponics (and or hydroponics) over planting in soil is saving water. Water does not get dispersed within soil, it is recycled back to reservoir and used again and again. Nutrient solution should be changed from time to time.

Even though hydroponics seems to be more known method, I prefer aeroponics for two main reasons. First is that root system has more oxygen available (therefore plants should be healthier). Second is that aeroponics is not that thirsty in terms of nutrients. I believe (but am opened to discussion) that moderation in nutrients is a good choice. Also, it has economic advantages if nothing else.

Why LED lights?

Using LED lights was a no brainer for me. Even though they are still quite expensive, their efficiency seems incomparable to other light sources. This goes hand in hand with the fact, that plants only need specific parts of light spectrum so that photosynthesis happens properly. Second benefit is that they emit hardly any heat so that there’s no big need for some temperature adjustment. Their long-expected lifespan is also important attribute that worth considering.

How it all went

I was growing with two different plant compositions. At first, I wanted to grow more demanding plants like tomatoes, strawberries or radishes. Later on, I found out it will be more convenient (especially in terms of manipulation and maintenance) to grow plants that are more similar to each other. Good candidates for these are various types of herbs. Different varieties of basil proved to be really worth growing in terms of harvest volume and taste as well.

Copious amounts of basil produced during second round of growing Copious amounts of basil produced during second round of growing

Lessons learnt

There are some lessons learnt along the way. Probably the biggest one was mentioned in previous paragraph.

Because of limited amount of space, I wanted to stuff all those different types of plants to that small place. It just does not work right. Different plants have different needs, grow at different speed, they heights differ etc. Given the fact that the LED panel emits light in a flat shape, we want to have all plants more or less of equal height. It was just pointless having tomatoes and radishes next to each other at the same time.

Second round of growing was much more enjoyable in terms of harvest volume. It actually ended up that basil has taken over other plants and all of a sudden the box felt like one big bush of basil. I did not mind that. Also in that second round, I started experimenting with cloning new plants. But that was using mistmaker that produces real aerosol rather than using low-pressure aeroponics.

The main reason I’m not growing right now is that the box was situated roughly three meters from my bed. While it is an awesome visual alarm clock when timer set properly, constant turning water pump on and off gets annoying in time, especially at night. It was possible to make it for those several months, but I would not recommend sleeping next to it to anyone.

Healthily looking root system Healthily looking root system

Tomatoes root system length illustration Tomatoes root system length illustration

Probably the most room for improvement was temperature regulation in reservoir. Recommended temperature of nutrients solution lies around 20°C. Temperature in reservoir tries the match the one in the room in hotter months. Roots then get sleazy and plants suffer without proper cooling system. I did not have one. Proper reservoir temperature regulation is inevitable in order to be able to have the system running for longer periods of time.

Why all this?

Mostly because it’s quite fun to have this geeky playground around. When growing aeroponically you have quite fast feedback loop from your plants as opposed to growing normally in soil. When you screw something up, you’ll find out really soon :). Plants seem to be more vital, they taste amazingly well. Having this kind of freshness in winter months is really hard to get even in fancier grocery stores around.

Also, I wanted to find out how hard is to have whole system running for several months without downtime. Even though I had some minor issues with my plumbing setup, the system was up and running for almost ten months without interruption. I removed artificial light in summertime because it was not necessary to use it.

If I had one spare room, I’d definitely continue with this. Obvious second step would be to add reservoir temperature cooling system and implement more sophisticated automation / monitoring for the whole system.


who am I? · I like to grow plants · develop on the web · and some more ·