Aeroponics - Can plants grow without soil?

STEM Chat
, , , ,
21

Mosquito net is too fine for roots. May be simpler to simply germinate in water and zip-tie the seedlings into place leaving the roots in the air in the tower. Will vary by plant I guess. They will grow to cling to support on their own. Or standard net pots with bigger holes.

The problem isn’t the medium, it is the pot. Some debris will always happen so no point obsessing over planting medium. As plants grow, there will be roots, possibly insects and etc too, so whatever the system is, it will have to be debris friendly. Getting rid of coir won’t solve clogging long term. As support, it is better than marbles, etc.

1 Like
22

Also aeroponics may not be a suitable choice for low budget growing. This tower, for example, could be converted into a much easier to maintain earthworm composter plus growing bin that composts household waste, grows plants and needs no electricity or additional fertilizer. Will try to draw a diagram.

IMG_20210112_013950_compress89
IMG_20210112_013950_compress892976×2835 616 KB

1 Like
23

I immediately checked out to see if I can buy the Raman sensor … Costs more than my plant collection. :joy:

But so useful!

One day,…

24

I have currently stopped growing vegetable crops sold by local farmers and but from them instead to support, but I have seeds of cyclanthera pedata available if you are interested. Interesting vegetable vine grows similar to cucumber and can be cooked too. Tastes slightly like Shimla mirch but milder. Can be stuffed too. Google it up.

1 Like
25

Isn’t it too short duration for a pump? Or I must be missing something.

26

I am using sprinkler nozzles with a pesticide spray pump that has two motors. The pump is on for 15 s and off for 30 secs. After 10 cycles stays off for 60 secs. The recycle container holds about 5 liters.
To prevent clogging of nozzle I made a filter out of a plastic bottle and a old sock. Works well - so far no nozzle clog.
https://metastudio.org/uploads/default/original/2X/2/233bd06b1a794902a401b58e43a4ca73f8ef0a21.jpeg

In my case it is both. The cup being circular leaves gaps at the side of the elliptical grow hole pocket. This elliptical hole is an artifact of my construction method and has mostly advantages in the support it provides over a regular hole. However with regular netcup it allows light to leak in and will cause algae growth. It also leads to runoff at the ellipse edge. The mosquito net being conical and very squishy plugs very very nicely into the elliptical blocking light very very well and only very occasional runoff.

2 Likes
27

To avoid germinating in a bed and then transplant, an extremely tedious process even with 160 grow holes, never mind the 1000+ setup that I plan, I want to plant in the netcup itself. This works very well subject to avoiding the seedling growing inside the tower.
In order to provide space for roots - especially thicker ones - the net cone is stapled at only one point. This allows the seam to widen to more than 35mm, a property that cannot be achieved with a regular cup. But it also leaves a small gap along the seam, causing the seedlings to grow through the seam INSIDE the tower. A regular netcup will also have the same issue unless it is filled with cocopeat.
The drain clogging is best solved by using 1.5" pipe instead of the 16mm drip irrigation, which I will do at the end of this cycle. The large dia will allow debris to flow into the reservoir where it can be removed easily. Adding a port hole should help too - just stick hand in and clear any clog.

The method we figured to allow growhole planting and avoid all the above problems is to anchor the seed at the ideal spot, which is 10mm before the netcup inner lip edge, using a material that can last multiple grow cycles. We can use cotton gauze or fishtank foam pad or @Pneb idea of using a piece of loofa image .
What better than a natural, spongy, water resistant mesh in which you can just push seed.
However the price is very steep at Rs.30-40 a piece in volumes of 200. Hence the PM to you @Vidyut

I have planted one cup with cotton gauze. It seems to be working. Will know in a day or two.

2 Likes
28

No. These are dc motors driving a diaphragm and blocking back flow. If there is back flow, water from the pipe and sprinkler will flow back into the tank. The pump will then have to recharge the pipe before water reaches the nozzle and 10 s will be too short. As there is very little back flow, stopping the pump for several minutes results in spray out of the nozzle in under 2 secs.

1 Like
29

You are doing it, so you know the practicability better.

Recycling water seems fine for hydroponics, but I imagine it would lead to high TDS water for aeroponics because of higher evaporation due to mist. Or maybe I am paranoid about TDS because the plants I grow prefer it to be very low.

The higher the TDS of the water, the lesser the life of the pump and nozzles (though it is very long regardless, unlike pizo element). But the nozzles will develop deposits with time that will eventually clog them.

But overall, the closer the TDS of the water is to rainwater (next to nothing), the healthier plants will be and the better they will grow. There is a reason monsoon brings lush greenery even in plants that get water.

What I am saying is that the design problem is not just physical - design, water, pump, sprinkler, etc, but also botanical.

If I were to be running a system like this, I would be providing very low TDS water and then for efficiency, programming the sprinklers so that there is very little waste rather than recycling the waste.

Inside the enclosed tower, evaporation will be very low. Most of the water will just drip down. 15/30 is sounding unnecessarily frequent for the application.

I mist an 8*2 balcony with four nozzles (for high humidity for the plants, not watering/roots). 20 liters of RO water (never recycled) lasts for over two days. 15/30 would be excessively wet even in this big a space that is open to air and breeze.

If the idea of aeroponics is a mist, once the roots are wet, and being wetted again before they get any time to lose moisture, this is almost close to hydroponics, just more expensive. It is just extra and wasted if the roots already have the water they need.

Instinct days the roots would grow even better with some access to air. ‘moist but not soggy’ is a good Mantra for healthy roots, though of course, with aeroponics, the risk is less than that with overwatering. Plus if the goal is low budget, conservative misting will be cost efficient on power.

Not sure if that makes sense in the practical setup you are running. Also I confess I have never done aeroponics.

2 Likes
30

A low cost DIY is on the cards. @Pneb and I know how to use line CCDs. Used them between 88 and 95. Cursing myself for losing 2 I had.
BTW if you can get hold of a Canon fax machine (probably other too) from the early 80s you could save on the cost of the CCD. It used a line CCD with green actinic light. image
https://e-publishing.cern.ch/index.php/CIJ/article/download/799/577/3552

2 Likes
31

Cotton gauze sounds too soggy long-term though will help rapid germination initially. Combined with the frequent watering, may encourage root rot unless you are planting really thirsty plants like cucumber, etc.

For your mosquito net preference, one fix may be too punch some larger holes in it for the thicker roots to find and use to get into the tower. As long as some nice thick healthy roots access the abundant grow space of the tower, rest of the mesh being fine should be a non-issue.

2 Likes
32

Makes perfect sense. I was planning to observe before changing the duty cycle. I will try a 20% duty cycle.
Using tap water - pH 7.5, EC 200uS. Added NKP to make pH6.5, EC 1500uS

33

You can also try starting cuttings in some of the grow holes. Will let you get an idea of suitability of setup for more mature plants faster than growing from seed.

While roots are inside the mosquito net, you don’t really know the efficiency of the aeroponics, just them growing in the moist medium. The roots have to exit the net into the tower and grow thick and healthy. Net pots have pretty big holes compared with a mosquito net. The roots have to be able to get thick and healthy for long-term health.

Or maybe just simply leaving the bottom on the net cone open for easy exit.

34

While I don’t have experience of aeroponics, I’ve been using a misting system for several years now. In my experience to get the real benefit of mist, short bursts work better than longer durations. 5 seconds mists your plants/roots. 15 seconds wets them. 30 seconds is like a watering can, just more expensive.

Misting vs irrigation

The off duration is determined by ambient humidity. Longer in monsoon, shorter in hot, dry weather. For my purposes, the mist should come on again before the plants experience dry air. For yours, it should probably come on again soon after most of the roots are no longer dripping.

2 Likes
35

The pump should do ok. All plastic and rubber. The nozzle will be a problem eventually. Evaporation is very low. Less than 1 li/hr between 11 and 5 for 4 towers with 160 holes with coir. replacing coir with clay balls seems to have further reduced that.

Several commercial setups in USA use a rectangular vertical casing with reticulated foam and a strip of gauze to act as wicking agent. This seems to have advantages of much lower power as water is dripped into the reticulated foam avoiding the need for pressure

1 Like
36

Interesting. How does that mist? Hydroponics?

1 Like
37

Did that day before - mint. Let see how it goes.

Will take a pic inside the tower tomorrow. The cones do have a 10 mm hole that easily expands.

2 Likes
38

Algae problem is because of excess stagnant water with nutrients + light. Blocking light, reducing TDS, reducing wetness will all help.

Algae is generally harmless unless you have it and/or slime suffocating roots. You could try a gravity fed UF filter to reduce algae load from recycled water. May not eliminate, but will prevent algae washed out by the water from re-entering.

3 Likes
39

Ah. That should do the trick.

2 Likes
40

No mist. Drips vertically on the top. The two pieces of sandwiched reticulated mesh with the wicking medium - gauze I presume. Plants sit in the sandwich, poking out of one side.

2 Likes