My First Hydroponics Bed / Tub

Also, the status of the “Lettuce In A Bag” test. First, the lettuce. This was inspired by the prior video posting where they grew saladings in a bag of potting soil in an overturned plastic box, using the lid as a support and the cover (transparent) as a kind of cloche or mini-greenhouse to grow greens in winter.

I decided to test the basic idea, but this not being winter, didn’t use the cover. Just put a bag-o-dirt in a tub and applied seeds. The first batch of very old lettuce seeds didn’t sprout. I bought some new and sprinkled them on. They DID sprout, but only a few. Then, some long time later, more sprouted. I suspect it was too cold for effective germination and that the warmest most sunny spot was the first few. You can see that in the picture where there are big lettuces in the middle, and little sprouts in the ends.

Lettuce growing in a “bag-o-dirt” with the top cut out and the bottom perforated.

Overall, it looks like it works pretty well. Given this, I’ll be making one of these that’s more like the original video for greens during fall / winter.

Some lessons learned:

1) Read up on germination temperature and don’t just sprinkle seeds and forget it.

2) Consider using a sprouter. I’ve had very great success starting small seeds in the sprouter I bought for the hydroponics effort. It is, in essence, a miniature version of the original inverted tub idea. A 6 inch tall clear plastic cover over a 9 x 13 or 11 x 17 inch sized plastic tray bottom. Rock Wool squares are put in it with a seed or two in the small center hole of each cube. Cover and keep warm & wet. Wait. Works GREAT (more in the bit below on hydroponics). It did not work well on large seeds like beans or peas as they could not effectively shove the rock wool out of the way to raise their heads…

3) Make sure it is complete “Potting soil” and not the cheap “garden soil – not for use in pots” that is deficient in Magnesium. These only really “took off” and grew well after I sprinkled Epsom Salt over the surface (about a table spoon).

4) In my very dry climate, in warm weather, using this tub method, 100% of water is used, none wasted. I sprinkle it and let the bottom get about 1/4 inch to 1/2 inch depth of puddle. That soaks into the bag through the bottom holes over the day or the next. No wasted water! So for winter, use the system that drains. For summer, use the tub to conserve water. Note that my bag is sitting in a plastic tub.

5) As the soil in the bag gets used up, watering with a hydroponics mix ought to extend the life of the bag for additional grows. I’ll be testing this with both fresh mix, and with “left overs” when a hydroponic solution gets changed out of a hydroponics tub. (General guidance is to change the solution after harvest, but it still has a lot of good stuff in it as your plants WERE still growing, so…. put it to use in the dirt garden.) I see this as a kind of “quasi-hydroponics”. It is dirt gardening, but treating the dirt as “grow medium” and all the fertility coming from hydroponic nutrient solution. I’m christening this “Quasiponics” ;-) In theory I’ll get to test it in about 2 months ;-)

Overall, I’m impressed with it. Nearly no effort and I’ve got lettuce to harvest. With some minor improvements in my care and precision, I think it’s a keeper of a method. I especially like that this is sitting on my cement patio with sun about 1/3 of the day. Essentially, this means any flat surface can be a salad garden. It also looks like the tub keeps various bugs and crawly things out (i.e. no snail problems so far!)

Sometime around next September I’ll go shopping for one of the big clear crate / box things as used in the video and make the actual cloche version to see how late into winter it keeps making salad ;-)

On to the real Hydroponics:

I have these big black construction tubs. At first I bought a couple to mix cement for fence posts and such. One day, having trouble keeping onions wet enough to not die, I placed a planter of them in the tub and ran water to about 2 inches deep (so about 6 inches of dirt above the water line in the planter). The onions LOVED it. It is the only time I’ve really done well with green onions from seed in warmer weather. Since then, I’ve used the same method on some other plants with decent success.

In my first foray into Hydroponics, I decided to “go cheap” and just float some styrofoam in the tub. It would have been much better to get a 1 inch to 1 1/2 inch construction styofoam insulation panel with the aluminum foil facing, but not having a truck, transporting a 4 foot x 8 foot board was “an issue”. Also it cost a lot for making one tub about 24 x 32 inches … So instead I bought a package of 6 syyrofoam boards of 1 inch thick and about 4 feet by 14 inches.

This picture shows the result. I’ve stacked the boards 2 high and drilled holes (after cutting to shape) as they are only 3/4 inch thick. IIRC, the actual length is 32 inches. The end bits from cutting down the 4 foot length got cut to make the strips with the smaller cups in them and to fill out the width of the tub.

AFTER I had it all made, I realized that the 3 inch big net-cups sat deeper in the water than the 2 inch ones. As the Kratky Method depends on having the solution just touching the bottom of the rock wool in the net cups and then dropping as the plants grow and use solution (so giving air access to the roots) that would be an issue. The 3 inch cups just fit a wide mouth jar… so I used jar rings to raise those cups “just enough”. In the future I’ll use just one size in a tub.

Hydroponics in a construction tub

In the start of the 2nd row is the little lettuce that started out as a very small sprout in the lettuce bag. It was placed into a net cup in a jar on my window ledge. Having not died, I’ve moved it to the bigger tub and with real hydroponic nutrient. The other cups are frilled with various things I’d started in the sprouter tray. They are all nearly too small to see. In the front row on the right are two cups using a rolled up paper towel (with cuts in it for the roots to get out) instead of rock wool. We’ll see if it rots or turns green or what…

On top of most of the cups you can see the little round clay balls that block sunlight from the solution (to discourage algae) and to give the plants some support. I discovered a feature of these that makes it worth buying them instead of cheaping out with gravel. They float. I had a couple run off into the tub while filling the cups. At first I thought I’d have to “go fish”, then saw it floating.

So, in theory, that’s it. Nothing to do but wait and harvest. The reality is that as these are floating, and have no “bubbler” in the water, I’m likely to have a root rot issue after a while. The “fix” for that is to either put some supports under the floating foam so it becomes a Kratky Method system, or add an aquarium air pump and bubble stone. I’ll likely do the latter as I have all that stuff “somewhere” in the garage already… OTOH, inverted plastic cups under the foam would be pretty easy to do. In any case, I have time as these are just freshly loaded.

The other things left as loose ends are to monitor the level of the nutrient solution, top up / add nutrients as needed, and I really need to get some pH measuring gear. I know fresh from the tap my pH is OK, but making it ideal (and keeping it that way) will improve things.

This nice thing is that now I have motivation to do all the fiddly bits / rest of it ;-)

Drilling the holes was pretty easy. Once I figured out that the 2 inch cups worked fine in a 2 inch hole… as the flange sticks out a little. For this thickness of float, I ought to use more like a 2 3/4 inch hole for the 3 inch cups, but I think my solution with the rings works nicely too ;-)

Today I made two more, different, systems. (Photos of them at some future time). The are substantially the same as the ones in this article, but with 2 inch net cups and I centered mine in the squares in the yellow lid.

One is a 5 gallon bucket from Lowe’s. 6 holes of 2 inch each in the lid. About $5 for the bucket and lid, then drill it. Add solution and net cups, put in sprouted cubes and be done. Surprisingly easy. Hardest bit was getting the plastic disks out of the hole saw. Note that running the saw fast is better. I tried very slow and it tended to catch on an edge, and then buck / tilt a bit and make a slightly irregular hole. Hold the material down hard on the backing board and drill it fast so it can’t ‘catch’ on the edge of the plastic as one side cuts through a bit before the other.

The other is a 17 gallon black plastic “crate” with a yellow lid. This is a softer plastic and tends to melt in the drilling. Again, cutting faster is better. It seems to be cut before it realizes it ought to melt ;-) It was VERY easy to make. I used just 2 inch holes as they centered nicely in the raised squares of the lid. 12 holes in a 3 x 4 pattern using every other raised square. I found I needed to move it around the pavers on the patio a little to find a more level spot than where I first put it.

Both of these two are straight Kratky Method as the lids are not floating, so in theory I’m done. The volume of solution is excessive (deep water at about “a foot plus” when 6 to 8 inches is more normal in professional gear) so unlikely to need added nutrients. This will consume more nutrient solution to fill the deeper tub / bucket but as I have a use for the “spent” nutrients, I’m OK with that. It also turns out that the nutrients can be purchased pretty darned cheaply. I got some very small almost sample sized bottles of liquid at $3 each. I’ve used up one of them for all three of these. Master Blend dry bag nutrients are much cheaper than that… Essentially two salads out of all that pays for ALL the solution even with the boutique bottle nutrients.

So far it has been far easier than I’d expected and the results are pretty clean to look at. All I need to do now is not kill everything ;-)

In California, we have 2 seasons. Wet and dry. This means I can just set these outside from about May to October. Sometime before October I’ll need to decide IF I want to try an indoor grow, and where to put these with what lights over them. I expect I’ll just store the construction tub inserts and only use the bucket or plastic box in my office for herbs and small salad stuff. I have a fair number of suitable light sources (LED bulbs and a big High Pressure Sodium that it seems is nearly ideal for plants. About 60 W IIRC so very bright.)

If you are in a place with lots of wind, the box and can might work, but the floating foam will be “gone with the wind” unless you get a lot of plant weight in it. If you get a lot of rain, there will be problems with dilution and even overflow of solution in the construction tub. The 5 gallon can and box will likely be OK as the lids ought to shed most of the rain and the lids snap on.

What has impressed me the most so far is that even with the process of drilling holes in the plastic (a one time job…) it was quicker and easier to set up this grow system than to deal with a similar area of “potting soil” in containers. (Remember that I just did that to get my garden started…) Buying and carting bags of potting soil, filling containers, moving containers. It’s heavy and dirty especially in the larger sizes. Water just comes out of the hose…

At this point I’m done with the hydroponic expansion for a while. I’ve got a total of 34 net cups in use and planted. I need to shift my attention to “operations” of the system and gain mastery of whatever goes wrong. I’m going to play with some quart or 1/2 gallon sized Kratky Method jars as I have some 3 inch net-cups left over. IF there are no significant problems, in a month or two I’ll likely make another construction tub ( I have enough styrofoam boards for 2 more in the package) and maybe another of the Lowe’s black plastic boxes. It was only $10 for the box, you just drill 12 holes, mix solution and that’s it. Less fuss than dealing with the foam.

Only real downside to the whole process is dealing with the styrofoam “snow” that drilling makes and the plastic “hair” from drilling when it starts to melt the hole instead of cut. So do that where clean up is easy. I did it over the lawn, so now I’ve got plastic speckles in the lawn… (Didn’t want a hard surface for the drill to hit… but in fact my “old fence boards” backing was quite enough). Next time I mow the mower will suck up most of those bits so I’m not real worried about it. Besides, UV breaks down the plastic eventually anyway.

Which brings up the point that I don’t know how long these will last in full sun. The black plastic ought to be fine. The yellow lid? Might need some paint… Then the blue plastic bucket? You would expect a construction bucket to be sun proof, but who knows. Finally the styrofoam. Maybe 2 years? I just wanted a quick test so that would be fine. IF it all works well, I’ll be replacing it with the foil covered board anyway.

One other thing that impressed me was what this means in terms of being “prepared”. Having a few boxes with pre-drilled lids, nested in a stack, a dozen pounds of Master Blend (it’s about 1 teaspoon / gallon IIRC) and some net cups stored in a closet means you can have a garden “set up and running” about as fast as you can sprout seeds (as long as there is a water supply, but without water you don’t need food anyway). That is just dramatically faster than heading out in the back yard and trying to bust sod, turn over a few ton of dirt, and hope the soil is decent and the birds and bugs are not too hungry. THEN using 85% MORE water… Especially in places without a lot of rain during growing season.

SO, OK, I’m still in the “glow” of that first success feeling. I still have pH, algae bloom, root rot, bubblers etc. etc. in my future along with an unknown number of dead plants and such to “discover”. I’m prepared for that and OK with it should it come to that. Yet if things are even 1/2 as easy in “operations” as it has been in the construction and set up, well it’s easier than turning a 4 x 4 square of garden down two shovel depths… and I’d be very willing to just “level and grade” that dirt and set a tub on it instead!

Subscribe to feed

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...
This entry was posted in Biology Biochem, Emergency Preparation and Risks, Plants - Seeds - Gardening and tagged , , . Bookmark the permalink.