Lettuce For Life!

If you take a head of romaine lettuce and eat all but the bottom 25mm/1inch, then place the cut-off stem in a bowl of water and leave it in the sun, something surprising happens. The lettuce slowly regrows. Give it a few nutrients and pay close attention to optimum growing conditions, and it regrows rather well.

lettuce-for-life-hydroponic-systemThis phenomenon caught the attention of [Evandromiami], who developed a home-made deep water culture hydroponic system to optimise his lettuce yield. The lettuce grows atop a plastic bucket of water under full spectrum grow lights, while an Intel Curie based Arduino 101 monitors and regulates light levels, humidity, temperature, water level, and pH. The system communicates with him via Bluetooth to allow him to tweak settings as well as to give him the data he needs should any intervention be required. All the electronics are neatly contained inside a mains power strip, and the entire hydroponic lettuce farm lives inside a closet.

He does admit that he’s still refining the system to the point at which it delivers significant yields of edible lettuce, but it shows promise and he’s also experimenting with tomatoes.

Our community have a continuing fascination with hydroponic culture judging by the number of projects we’ve seen over the years. This isn’t the first salad system, and we’ve followed urban farming before, but it’s winter strawberries that really catch the attention.

68 thoughts on “Lettuce For Life!

    1. Hey, man. We can jest, but it’s projects/people like this that is going to lead to something crazy when some random serendipitous event occurs. Someday, someone’s going to drop a peppermint into the bucket, and the next thing you know, we’ll have a way to grow lettuce leaves that are super-conducting at room temperature, and are 15 times more diamagnetic than pyrolytic carbon!!

  1. My wife did this with celery. When she planted it, a few hours later the dog ate it… A useful hack would be to figure out how to use an Arduino to keep my dog from doing that again. I tried sitting there with Arduino in hand, ready to throw it at the dog if she ever got close, but then I got board and left to make a sandwich.

    1. “got board? Nice to see that the autocorrect AI is developing a sense of humor.. Anyway, instead of sandwiches you should be eating celery stalks with PB & banana, giving you an endless supply of celery rootlings and a use for all that celery if the project ever succeeds.

    2. Hack for that, sans Arduino: Obtain an ionizer module (either from an air filter, or buy separately off Ebay). Connect the output lead to a large nail. Stick the nail in the soil of the plant you want protected. Make sure the plant isn’t grounded in any way.

      Now your celery is a small capacitor, charged to 4-6KV, and ready to deliver a harmless but startling shock to anything that touches it.

      1. Or put a NFC tag in your dog’s collar linked to a shocker, and an NFC shield on the arduino.

        I’ll leave the rest up to you, but, I think you get where I’m going

  2. Nice to see others exploring this as well.
    I’ve been doing this for a few years with (1) spring onions & (2) coz, gourmet & salad lettuce but, there are a few caveats; re 2 average temp needs to be less than ~15-17C otherwise bacterial growth overwhelms the root system and the water level needs to be higher too if temps get lower – not so much with 1 but, in 1’s case mosquitoes & other insects affect the lifecycle & both need fresh water and suitable nutrients. With 2 if the lettuce gets too tall its leaf taste declines & gets more bitter – the sap becomes white & sticky as it prepares to grow into a plant of appropriate gender for budding. When I had an outside area the lettuce wuld grow to 900mm tall – with benefit of some ‘human delivered’ phosphates & urea, collected a few seeds from that too which grew well. So that cycle one started & maintained, at least with gourmet variety meant an endless supply :-)
    Since I don’t have patience to delve into specific nutrients I let them go for a week or two each then cut out whats edible & ditch the rest as they get weaker. Replacing each with new bought items. In any case I get up to 4 generations on average of spring onions & 2-3 with various lettuce types. Makes for a nice display.

    I’m sure this can be taken further as a commercial product for the enthusiastic cook with Ph & temp meter logger wifi signalling etc. Anyway,thanks for bring this to our attention, lots of opportunities for electronics additions :-)

    1. set up photo’d above has 7 net baskets for lettuce heads.

      Grow light I have is 125 watts, and runs about 8 hours a day or 1 kilowatt hour a day, or ~11 cents a day.

      takes about 30-60 days for lettuce to mature in such an environment (depending on type). $3-$7 in electricity or about $0.40-$1.00 per head of lettuce. Of course nutrients have a cost too as does any pump you are running to keep the water moving. We’ll call it $0.80-$2.00.
      Head of lettuce at the grocery store costs $1.50 to $2.50 (best guess don’t have a grocery store handy to check at.

      Over all your milage will vary both because of the cost at a grocery store and the cost of power…. but this is economically viable at least some of the time, AND fresh lettuce tastes way better than store bought (which spent days on a truck).

      Personally I grow outside when I can, sun’s energy is free to me, and if I plant in the ground I can leverage waste food/organic matter for compost I can use for nutrients instead of paying for fertilizer.

        1. HAD projects often have an off the shelf equivalent that is cheaper, but it is more fun to learn and build something with your own two hands. Why grow food when you can buy it? Creating your meal from what used to be a patch of dirt, is just as satisfying.

          1. No it’s not.

            It sets up a rational decision making process.

            My time is worth $X.

            Therefore if I have to make a decision on spending my time on something, it better be worth the equivalent labor it takes me to earn $X or provide me with the same level of entertainment that spending $X provides.

            Meaning, I don’t spend my time on things that aren’t “worth” it.

            It puts a $$$ value on the phrase “worth it.”

            Make / Buy can apply to your life not just to a business decision.

            Tomatoes, yes. They taste better.

            Strawberries, yes, no pesticides.

            Onions, potatoes, celery?

        2. evad asks “How much is your time worth? Your personal hourly rate?”
          About AUD$200/hr consulting in Food Science and/or Electronic Engineering depending on level of responsibility for the type of projects undertaken.
          But note, it takes mere seconds to put a lettuce in a bowl with enough water after washing when unpacking from the shopping bag AND watching it grow is free entertainment & the immense satisfaction of eating it free just when I like without concern for my efforts declining the profit base of the multi-national grocery suppliers.
          Perhaps evad, you can arrive at a comparative analysis of the seconds spent setting up the bowl with water vs the $ saved buying3 to 4 more to replace that grown ?

          Growing from commercial product in the kitchen with natural lighting can also do this with capsicum & a few others provided they grocers don’t chill them too much. Has me enthused as there are a few vitamin supplements worthy cutting the capsules open as some B group at suitable dose aid plant growth – that and a few hormones found in other plants.

          Perhaps someone might like to look at making up a larger narrow wide container with part light part shaded and introduce some fresh water small baitfish with say water cress – then the fish fertilise the plants and when you have enough fish then fry em up as garnish for the salad – pH meter in that respect would pretty much be a necessity…

      1. Thanks for the economic breakdown. I now know that raising lettuce in this fashion would cost 2-3X buying fresh at the store.

        As an aside, do you live in Alaska?

      2. Hey John here are the true Wattages
        45W from 225 LED Grow Light Lamp Panel.
        27W from .Active Aqua, 400-GPH Submersible,Hydroponic, pump
        1368KW/hour if light is ON for 16 Hours a day.

        That means it cost $4.51 Dollars a month for entire system, plus the amount of water you will save compared to traditional gardening.

      3. Here the kWh costs more like 22cts and the lettuce, depending on store and season less than 1€. As I already said to a colleague years ago when he asked about artificial lighting plants (he spoke of tomatoes): “I think, there is only on plant worth growing under artificial light, but it is rarely eaten.” Perhaps sometimes as ingredient in special cookies. :-)

    2. Usually, no one can beat specialization and mass production in terms of price. Especially when you compete with big farms that uses sunlight and have very specialized people and tools for each kind of crop. So, a lettuce from the market will probably be cheaper then growing it in your home.

      Still, growing your own food can be very rewarding in many other ways, but not in terms of cost.

      1. Depends on how much organic veggies cost in your area. As well as seasonal availability. Then there’s the “carbon footprint” argument some people care about.

        Placing the grow area to take advantage of natural lighting drops the cost further.

    3. Cost me nothing as its in pots on the kitchen window sill, might be a bit slower but hey just have a couple more and its more than adequate plus not having artificial lighting means the plants respire their O2 cycle more naturally at night which I expect would be more nutritious as its in line with natures cycles, depending of course on the plant as the carbs to protein equilibria is shifted with artificial lighting and this can mean chance of cyanogens affecting protein content especially so if you lift the CO2 content as some food plants are more adapted to pre industrial CO2 levels & higher CO2 not only means they need more water but the extra CO2 allows the plants to generate more chemicals ostensibly as means to offer greater resistance to being consumed. So be careful if you are tempted to make a light box & add extra CO2…

  3. I hate to be “that guy”, and this is cool in a kind of science fair kind of way, but lettuce seeds are cheap and easy to grow and grow a whole head of lettuce instead of a little tuft of leaves.

    And you have a much wider variety of greens to choose from, almost all of which are more flavorful than whatever variety of store-bought lettuce that’s chosen for its ability to be shipped 3000 miles instead of its flavor.

  4. It is sad most of the comments are negative. This would be a great project for schools. Also, having home grown things of the varieties you want, and free from pesticides and other nasties sounds great to me. You could grow fresh stuff all year round too. Not everywhere in the world have instantly available cheap stuff available. If you do, count yourself lucky and please try not to flame those who may not be as fortunate as you and can see that as a very handy setup.

    1. This is a good experiment for educational purposes, but the negative comments are important feedback for the other perspective experimenters. The title “LETTUCE FOR LIFE!” is fun click-bait, but its important that we maintain realistic expectations. Convincing an impoverished person to engage in a net-loss farming technique would be an evil deed, no matter how good that technique makes us feel.

      Its our instantly available cheap energy that lets us fantasize about growing food using only artificial light, fertilizer, and robots. All three of these things rely on our dead dinosaur supply, if you extend the conceptual tail pipe you find that these projects aren’t even very “green”.

      When it comes to food production if its not economically viable, its not viable “.”; That said future breakthrough technologies may completely change this reality and experiments like this may get us there.

        1. I didn’t say it could never be viable, just that it currently isn’t. I’ve been experimenting with this kind of small scale food production for about 7 years and am stressing the need for critical thinking and dissensus.

          I can reliably produce lettuce for less then 10 cents a head (material cost) via organic outdoor garden methods with weekly harvests for 8 months out of the year. If I move that operation indoors my material costs jump to 20-25 times that. Even if those were sold at a slight profit, it would take over a year to recoup the initial infrastructure investment.

          Automated indoor food growing is a pleasant and appealing narrative that often doesn’t usually survive contact with practical constraints.

          Notes: Disney sells enjoyable narratives, NASA has an otherworldly mission and Wholefoods sells enjoyable narratives at otherworldly prices.

  5. TL;DR; I’ve done this with lettuce but the results are better with plants that have been started from seed and never harvested to a root stub.

    The store bought lettuce stub will regenerate roots and leaves, but supermarket shelf time without water causes a biological trigger to push the lettuce to bolt (this means the lettuce will rush to produce a seed crop because it thinks it will die of drought). The result is a sickly plant diverting its energy towards and undesired yield (ie: new roots, seed heads).

    My Observations:
    1.) If the roots remain intact and you refrain from taking a devastating harvest the plants stay healthier and produce a new leaf yield faster.
    2.) Indoor growing requires enough supply/electrical/biological inputs that the result is usually a net loss. Its a fun novelty that can only be sustained by inflated market prices on certain crops where cultivation is difficult/illegal.
    3.) After some number of harvests of a single plant you land yourself diminishing returns, nature solves this problem via reproduction
    4.) Succession planting lettuce outdoors from seeds is a highly effective “hack” for producing food at a net gain.

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