Hydroponics First Harvest Time?

What a difference a few days make. I think my first lettuce is ready to harvest!

There are two smaller (later started) lettuces in the front row that it is starting to overrun, so I think maybe it needs to be on a plate ;-)

Hydroponic Lettuce Harvest time

Hydroponic Lettuce Harvest time

For more direct comparison with the prior images, here’s a shot from the front of the tub. Notice that I’ve moved one of the “paper towel” cups toward the center and put a new plant in the corner. I don’t know why one of those “paper towel as media” plants is thriving and the other is stunted / slow. Also I replaced the two dead cups with other things, one being some green onions. Oregano in the corner. So far they are doing fine. This picture can be embiggened to about double size if you click / open it:

Hydroponic Tub June 18, 2019

Hydroponic Tub June 18, 2019

Here’s links to the prior postings:

Just 4 days ago: https://chiefio.wordpress.com/2019/06/14/update-on-hydroponic-tiny-garden/

Hydroponic Tiny Garden at 2 weeks

Hydroponic Tiny Garden at 2 weeks

Then about 16 days ago: https://chiefio.wordpress.com/2019/06/02/my-first-hydroponics-bed-tub/.

Hydroponics in a construction tub

Hydroponics in a construction tub

In Conclusion

Frankly, I’m a bit stunned by how fast these are growing. Those other lettuces, at this rate, will be ready for the plate within a week. It looks like I need to plan my plantings better, maybe just one lettuce every few days ;-) Either that, or get ready to eat a LOT of salads!

Near as I can tell, this floating raft is working better than the Kratky Method 5 gallon can and 17 gallon box / crate. Part of the problem is that I planted the rock wool cubes too early. There is a ‘race condition’ in the method where the water drops as the roots grow, so you get some air on the roots yet they get lots of nutrient solution. All fine UNLESS you plant a dozen cubes of 3 or 4 different things very early and they do not yet have roots outside the rock wool. The fast growers survive, the slower ones don’t get roots into the solution before it drops away from the “just touching” the cup, then they start to dry and die. No such issue in the floating raft (though you risk poor roots from lack of oxygen… easily fixed with a few ml of hydrogen peroxide OR an aquarium air stone / bubbler; though I’ve not done either yet).

I’m going to let this tub run without any bubbler just to see if eventually it is an issue, or not. IF the roots start to look a little brown, that’s a lack of oxygen indication and I’ll add a Tbs or 2 of hydrogen peroxide.

So, OK, I need to sprout more slowly and selectively, and plant them out after they are bigger with better root development.

Which brings up another advantage of the raft. You can just change cups / plants at will. The Kratky Method has a steady drop of nutrient level so once underway, and “replacement” plants must have more roots to reach the solution. This does mean that I can move bigger plants already in cups from the raft to the Kratky tub as “replacements”, though. So having a raft in production is a feature for the Kratky system tubs.

I suspect part of the advantage the tub has is coming from the extra light reflected by the white surface. So not only are the plants getting more contact with the solution but they are getting a stronger dose of input solar power ;-)

At this point, I’m just going to make more rafts to fit my construction tubs. That will be two more of these. One will just be salad fixings. Another onions (as long as these onions continue to grow / thrive) and maybe some herbs. The third? TBD. It will get some experimental stuff and “we’ll see” what survives “Darwin’s Hydroponic Garden” ™. ;-)

I think I’ll make one that’s all 2 inch net cups (and move these 2 inch into it) and convert this one to all 3 inch. Then depending on how these lettuces do on the crowding, maybe with fewer cups / wider spacing. OTOH, lots of “baby lettuce” is tasty and tender ;-) I also need to decide on “cut and come again” or not. Normally you get about 3 harvests before they start to get a bit bitter, but I don’t know if that will hold for the Hydroponic lettuce too.

You can’t see it in the photos, but the replacement plants were transplanted from a dirt pot. I just rinsed off their roots and put them into the cup with the little ceramic balls around them. That seems to work just fine, and as I’m not fond of the rock wool dust (why you MUST wet it first before you do anything else) I may well just do all my starts that way. It does assure bigger roots at planting out and that they can reach the nutrient solution.

So to say I’m happy with the results would be a great understatement. Compared to my repeated “issues” trying to grow lettuce in the ground, this has been very easy, very effective, relatively pest free (especially like the lack of snail and earwig ‘issues’…) and astoundingly fast.

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About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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7 Responses to Hydroponics First Harvest Time?

  1. E.M.Smith says:

    On the 3rd cutting of the “Bag-O-Dirt” lettuce, it has started to bitter. I just harvested a bit off along with that one from the hydroponics. As I like bitters, but the spouse doesn’t, I just had a large dinner plate sized “Brunch Salad” that was about 1/3 the Bag-O-Dirt and 2/3 the hydroponics. That still leaves a very full dinner plate pile of just hydroponic lettuce for the spouse.

    Added 1/2 dozen olives from a can, and one hard boiled egg, in quarters, then dressed with Ranch Dressing. YUM!

    I’ll likely keep the Bag-O-Dirt going just a little longer, for me for bitters. Then again, the younger leaves were not bitter, so it may just be that I need to not let it grow big old leaves. I think I need to learn a bit more about actually choosing and harvesting lettuce, now that I can grow it well ;-)

    Last time I’d harvested the Bag-O-Dirt there were some small bugs on it. Sort of aphid sized dark and some clearly green aphids. I’d noticed some small wasps working over the area. This time, no bugs at all on either of them. I think the wasps swooped in and cleared them out ;-)

    The lettuce was wonderfully sweet and crisp. Nearly no defects of any kind in the leaves.

    We will now find out how well it does as “cut and come again”. Though really, given how easy it was to just pluck this guy from the Bag-O-Dirt (well, really, lift with a teaspoon sized grapefruit spoon) rinse the roots and put it in a net cup, I’m thinking that just starting a few new seeds every week or two and always having “first cut” fresh lettuce is sounding very nice too ;-)

    Having had my first harvest, and one lettuce being enough for 2 plates or 3 to 4 “side salads” and it being very tasty, I’m quite happy. Success at lettuce, at last! And no bug / snail problems.

    If I can get green onions going along with some choy, most of my vegetable department shopping (other than potatoes and other roots…) will be done. At least in 3 seasons of the year. ( I’d need a bigger house or a greenhouse to do things like zucchini in winter…)

    Having had a wonderful forkful of salad, I’m now committed to this method. IF it needs it, I’ll get a bubbler to extend the growth period / get better growth (though this seems quite well enough!).even if that means laying a drop cord to the space. Similarly, when it starts getting cold in fall, I’ll be looking to put a cloche over this, or move it inside with grow lights. I’m sure it will be slower with the lower light intensity, but I’m OK with that ;-)

  2. beththeserf says:

    Say Em anuther Norman Borlaug Green Revolution . :)

  3. p.g.sharrow says:

    A most interesting post and set of comments for me. Figuring out a dependable home grow for MILD tender greens would be a useful talent to have. I have found that a limit on sunlight and heat is necessary.as well as a consistent water supply. Bugs and vermin can also be a problem that must be delt with.
    Getting everything to work right all the time is quite a challenge, but that might be a “Feature” to some people. A well made salad is a work of art, A melody of taste and textures, Even a complete meal…pg .

  4. E.M.Smith says:


    Maybe “Hot time, summer in the city!” after all, I am now growing salad over concrete in the suburbs…


    From what I’ve read and now done, it looks like lettuce is one of the easiest plants to grow hydroponically. Very forgiving. Hardest is root crops. Tomatoes and cucumbers in between.

    Their are at least 5 common methods (systems) -of increasing complexity (and success with difficult plants). Kratky Method, Deep Water, NFT Nutrient Film Technique or thin film, Dutch Bucket, and aeroponics. Plus some gradation between them. So I’ve seen a video of a guy growing cabbage in a PVC pipe system built like NFT but with perlite / media in the pipe like Dutch Buckets and drip watering on a timer.

    My Lowes crate and 5 gallon bucket are running as Kratky (solution level allowed to drop) but I’m likely to make one Deep Water (solution kept topped up and aeration added) like my tubs/rafts.

    Eventually I’ll make some kind of Plumbers Delight to explore NFT. But likely next year. Dutch Bucket with 5 gallon cans of perlite or similar is common. Basically, rows of cans with drains about an inch off the bottom into a return line to a tank via gravity. Pump and timer in the tank water the top of the buckets periodically via more PVC and drip watering fittings.. That will be when (if?) I decide to try roots and fruits…

  5. E.M.Smith says:

    Oh, and at some point I need to compare proper hydroponic nutrients to just fixing my own. Saw a video where a guy did just that with lettuce. Compared Master Blend (common commercial product in 2 or 3 parts and you customize the blend to the specific crop) to Miracle Grow with added epsom salt to one other. IIRC the Tomato Miracle Grow with one spoon of epsom salt per gallon was about the same as the commercisl stuff and a lot easier to find.

    I’m also still a tiny bit queasy about shopping in a Hydroponics Head Shop with loads of stuff directed at the M.J. Folks. While it looks like California no longer cares, at one time the local police watched them to bust pot growers. A Dad got a police raid after leaving a shop with a full growing kit in shopping cart … for his son’s science fair project….

    So maybe I’m being a bit paranoid, but I’d rather get larger sized bits of chemicals and pots / pipes at the hardware store….

    I was happy to buy real net cups there, though… There are lots of videos showing folks making their own from plastic Dixie Cups and a soldering iron, to melt holes, or knife / scissors cutting them. So it is possible to do it all without leaving tracks to the hydroponics store. As privacy is one of my hot buttons, it might be fun to do an entirely “below the radar” exemplar system :-)

    OTOH, my hydroponics set up is visible from the front gate so anyone scoping the place out ought to see it is lettuce….

    But I like to play with stuff, so I am going to try the Miracle Grow Mix My Own at some point.

  6. E.M.Smith says:

    This article is interesting as it shows different DIY systems. About the 3rd photo down is one using very large PVC pipe and net cups made from plastic drink cups:


    There are some silly constructables like sites with directions to make these using an electric drill. Really? Power tools when “poke it with hot nail” is enough? (One video from some poor overseas place used recycled drink cups, a fire and a nail… very useful idea for an EOTWAWKI no electricity situation).

    I chose to buy real nutrient and real net cups for my first trial just to eliminate possible failure paths while I learned how to do it. Now I’m thinking of loosenig those constraints.

    FWIW, for a periodic water system using no electricity, I’m musing about making a very shallow V of pipe with a fat T as a tank on one side, then a longer pipe of net cups on the other (or perlite filled stubs). IF designed right for balance, it ought to be bi-stable with either plants up, solution down in tank side, or plants down, solution in their side. Just push on one end or the other to change state once per day….

    So a long small pipe (or pipes) with holes, reducer elbow to a fat pipe cross pipe fulcrum, then it has a T to a fat segment continuing the first line (with the elbows giving about a 20 degree slope). Or similar. A bit tricky to get volume sized right for tank side while balance kept bi-stable as plants grow and add mass, but there are enough variables it ought to work…

    Water is very heavy and it moves so ought to dominate the balance. Mostly just match the mass of small and fat pipe lever arms on the fulcrum cross pipe. Worst case is you hang a chunk of heavy on the fat pipe clean out nut when the crop is too big :-) I’d likely make it with about a 5 pound bias to the fat side down position to allow for 5+ pound of crops. Then figure a 5 gallon “tank” capacity will be about 5 x 8.25 = 41 pound of shifting balance weight, it ought to work.

  7. Pingback: Hydroponic Update 26 June 2019 | Musings from the Chiefio

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