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 ;-)
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:
Here’s links to the prior postings:
Then about 16 days ago: https://chiefio.wordpress.com/2019/06/02/my-first-hydroponics-bed-tub/.
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.