Simple Kratky Method Hydroponics Experiment

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Eric in Japan
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Simple Kratky Method Hydroponics Experiment

Post by Eric in Japan » Thu Mar 10, 2016 8:39 am

I have always been interested in hydroponics and aquaponics. I've tried many different systems over the years. Now I will try another that doesn't need any electricity, timers, or gadgetry. "Set it and Forget it."

First, I went to the home center and got a few things. A big sheet of styrofoam, and a big plastic tub.
(Ok, I had the tub already. It is a bit big for this experiment, but waste not want not...)
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Next, I flipped the tub over on the styrofoam and traced it out.
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Then I cut it out.
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Here it is cut and trimmed to size.
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Next, I measured, marked, and changed my mind a few times about where the planting holes should be.
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And I finally cut them out with a hole saw. It ended up a bit messy. A utility knife would do as well.
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Now I can put cups (with holes in the bottom) into the holes to hold some kind of growing medium. I am planning on starting some of my recently acquired seeds (thanks Paradox and Zasso!) into some old rockwool I have lying around. Then I will put some expanded clay pellets or pebble sized rocks around them in the cups.
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When the weather is right, I will move it to its final location, fill it with a fertilizer/water mix, tie down the top, and put the cups in. And (if the Kratky method actually works) I will walk away, never look back, and harvest 8 heads of lettuce in 40 days.
  • The theory is that you fill it so the cups/pots are sitting 1/3 in the water.
    The roots grow down into the water, and as it is used, the water level drops below the pots.
    Roots keep on growing down into the solution to get the water, and the older roots and a few newer ones as well get oxygen from the humid air in the gap between the lid and the water's surface.
    The method is supposed to be very good with leafy crops like lettuce, spinach, chingensai, etc...
    It is better to grow just one kind of crop at a time, as more vigorous plants might strip the water down faster than the less vigorous plants.
    After harvest, you can refill and plant again. But after three cycles, they recommend using the leftover fertilizer on houseplants or in the garden and starting fresh.
    Of course a balanced hydroponics fertilizer is maybe best (http://www.rakuten.co.jp/eco-guerrilla/ ... ch_conf_02), but you can also use hyponex plant food.
Here is an embarrassingly childish illustration of the principle.
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You can do it on a much smaller scale as well. One lettuce plant will use about 4L of water to grow to maturity. So if you have a 4L empty shochu bottle, you can spray paint it opaque and put a plant through the lid. Basically any container will work, providing you can suspend the plant at the top, and prevent algae from growing in it.
I have an old hydroponics book that recommends strips of an unwoven synthetic cloth- like the range hood filter you might use in the kitchen. Cut in strips, put 2 seeds at one end, then wrap the top inch or two with bubble wrap until it is the desired diameter. Then just use it like a cork to stop up the hole. The long strip acts as a wick and keeps the seeds and seedling hydrated. A kitchen sponge folded around can also hold the wick and plant in place. Be inventive.
Search Kratky hydroponics on Youtube and you will see dozens of videos and tutorials. (I recommend mhpgardener)
"... so, the cucumbers said to the cabbage, `Lettuce Go.`"

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Re: Simple Kratky Method Hydroponics Experiment

Post by Zasso Nouka » Fri Mar 11, 2016 7:37 am

Eric in Japan wrote:I have always been interested in hydroponics and aquaponics.
Really Eric ? It would seem a large percentage of the Internet also shares your interest with so many sites dedicated to hydroponics :lol:

That looks like an incredibly simple yet effective idea, can't help but wonder if you could add a few medaka below and easily turn it into an aquaponics system or would there be issues ensuring there was enough fertilisers for the plants do you think ?

Certainly interested to see how you get on with it.

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Re: Simple Kratky Method Hydroponics Experiment

Post by Eric in Japan » Fri Mar 11, 2016 7:56 am

I think if you add fish, you need aeration. Also, the organic waste of uneaten fish food, and fish wastes would probably jam up the system.
There is a guy in Matsudo who runs Japan Aquaponics http://www.japan-aquaponics.com/index.html
He would know for sure if it was possible. I took a course a few years back from him. Was a lot of fun and learned a lot.
"... so, the cucumbers said to the cabbage, `Lettuce Go.`"

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Re: Simple Kratky Method Hydroponics Experiment

Post by Eric in Japan » Fri Mar 11, 2016 9:20 pm

And I made two more smaller ones, this time from just things I found at the 100 yen shop.

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  • A styrofoam board = 108yen
    Two planters with no drainage holes =216 yen
    Two small flowerpots = 108 yen
    A bag of "Hydro Bowls" (I think they mean balls) = 108yen
    A bottle of fertilizer = 108yen

    total: 648 yen for 2 planters.
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This fertilizer was actually a real score (if it actually has all the ingredients listed). 20 micro-nutrients that most liquid fertilizers you find at home centers just don't have. They aren't necessary if you are growing in-ground, but you should have them for hydroponics.

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I traced and cut out a slightly smaller hole in the center so the small pot could fit. The lip on the small pot keeps it from falling in.

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I filled it with hydro-balls and stuck that spider-plant in it for the picture. Then I added 1/4 the bottle of fertilizer, 4L of a quality 6-6-6 liquid fertilizer, and planted lettuce in it.
"... so, the cucumbers said to the cabbage, `Lettuce Go.`"

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Re: Simple Kratky Method Hydroponics Experiment

Post by Zasso Nouka » Sat Mar 12, 2016 6:54 am

That's sheer genius sourcing all the items from a 100 Yen shop Eric

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Re: Simple Kratky Method Hydroponics Experiment

Post by paradoxbox » Sat Mar 19, 2016 8:47 am

Those are some cool projects you have going! The 100 yen fertilizer is quite a score, I will have to check my local shops to see if they have that.

Does lettuce not suffer from root rot at all? I thought most hydroponic operations have some kind of a flood fill cycle or other method of oxygenating the water so the water doesn't just turn into stagnant sludge after a while.

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Re: Simple Kratky Method Hydroponics Experiment

Post by Eric in Japan » Sat Mar 19, 2016 7:57 pm

From what I understand, leaf lettuce is such a short cycle plant (30-40 days) that it doesn't have time to become a sludge. But you are right, most hydroponics have aeration to prevent root rot. I am a bit worried about the strawberries I transplanted into two of the Kratky pots. (I have nine pots now!) The strawberries are probably too long term, and root rot is a real possibility.
"... so, the cucumbers said to the cabbage, `Lettuce Go.`"

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Re: Simple Kratky Method Hydroponics Experiment

Post by gonbechan » Sat Mar 19, 2016 8:18 pm

If you are growing the strawberries in the bigger box, you could just get a cheap fish air pump stone thingie and make a hole in your top thing and pass the pipe through.

Sorry but I have no idea what that fish tank bubble thingie is called. But they are relatively cheap.

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Re: Simple Kratky Method Hydroponics Experiment

Post by paradoxbox » Sun Mar 20, 2016 6:47 pm

gonbechan wrote:If you are growing the strawberries in the bigger box, you could just get a cheap fish air pump stone thingie and make a hole in your top thing and pass the pipe through.

Sorry but I have no idea what that fish tank bubble thingie is called. But they are relatively cheap.
Aerator or aeration stone I believe. Yup, I have heard of small scale hydroponics users and aquaponics people using these to oxygenate the water.

Another option I've seen is to have a continuous loop of water splashing into the tank from a high place, the splashes aerate the water enough to keep fish alive, and certainly enough to stop root rot. Just place a pump at the bottom of the tank and put the exit hose on the edge of the box. I've seen this done in both aquaponics and a similar principle in Sepp Holzer's ponds.

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