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Slow Growing Plants


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  #1  
Old 06-30-2009, 08:34 AM
RedHerring RedHerring is offline
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Question Slow Growing Plants

Hey all,

I've got a bit of a problem. I'm running an aeroponics system (it's a tote-bin with drip on the perlite and misting below and reservoir at the bottom) as well as a few potted plants as a control. Now I've got a green-pepper plant growing in the aeroponics system and a few other things in the potting soil but they're all growing incredibly slowly. Basically the get a pair of adult leaves then sit there doing nothing. They all look happy; good green leaves, nice and glossy with no spots or discolorations but they just don't seem to be getting bigger.
Here are a few measurements:

Air Temp: 10-22C
Water Temp: 18C
Humidity: 20 -30%
Light: 18h on 6h off. 6x 70W high pressure sodium + 1x 85W/5100lm "Daylight" fluorescent tube.
pH: 6.3
EC: 0.68 mS


Any ideas?

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Old 07-01-2009, 11:24 PM
GpsFrontier GpsFrontier is offline
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Quote:
Originally Posted by RedHerring View Post
Hey all,

I've got a bit of a problem. I'm running an aeroponics system (it's a tote-bin with drip on the perlite and misting below and reservoir at the bottom) as well as a few potted plants as a control. Now I've got a green-pepper plant growing in the aeroponics system and a few other things in the potting soil but they're all growing incredibly slowly. Basically the get a pair of adult leaves then sit there doing nothing. They all look happy; good green leaves, nice and glossy with no spots or discolorations but they just don't seem to be getting bigger.
Here are a few measurements:

Air Temp: 10-22C
Water Temp: 18C
Humidity: 20 -30%
Light: 18h on 6h off. 6x 70W high pressure sodium + 1x 85W/5100lm "Daylight" fluorescent tube.
pH: 6.3
EC: 0.68 mS


Any ideas?
I don't see anything wrong with the air temp or the water temp and the humidity should be fine. I don't really have any experience in lighting because I use the sun for that. Although I cant tell from your post if you are using potting soil in the hydroponic system. Perlite should be fine but regular potting soil will have elements and minerals in it that will through off a Hydroponic nutrient solution.

It sounds like the plants are getting enough water or they would be wilting. So I don't think that is a problem, unless they are constantly soaked and don't get enough oxygen. There might be a problem with the nutrients you are using, I am using General Hydroponics Flora series 3 part system because they are pretty reliable and standard in the industry. I don't know that what you are using is not reliable, but it might be worth investigating. I also dont know how often you change the nutreants or the size of the resevar.

I am interested in the setup you have for the aeroponic system, I am very interested in that technology. I am particularly interested in the pump you are using and if it was expensive. Also what kind of pressure it provides and how many emitters that it is capable of supporting without pressure loss.
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Old 07-02-2009, 06:49 AM
RedHerring RedHerring is offline
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Definitely not using potting soil in the system. That's in pots next to it. The idea was to see how much faster the plants grow in the hydroponics than in the soil. The nutrient solution is a three part, home-made one I picked up from a hydroponics shop in Cape Town. The owner showed me the kind of things he was growing and the concentrations he was using so I'm assuming it's good.

The pump is a cheap thing from china I picked up at the garden shop. It pumps about 800 L/h which is not quite enough to give my five misters the pressure they need but it seems okay. They don't so much mist as they do spit.

Here are a few pictures
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Old 07-02-2009, 06:51 AM
RedHerring RedHerring is offline
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Oh, and the reservoir is 30 L. How often should I be changing the water? That's the one thing I've never been too sure on. At the moment it's just the three plants in there and they're pretty small.
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Old 07-03-2009, 03:39 AM
GpsFrontier GpsFrontier is offline
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30 liters would be roughly 7 gallons, I can't Imagen that being a problem for plants that size even though peppers are heavy feeders. If the plants that are in potting soil are getting the same lighting and are growing faster I would think that the lighting is sufficient. I would half to say the problem must be in the nutrients. I don't know what you are using because you said it is a special blend so I cant even look it up. I would consider talking to the guy at the Hydro store to see if he has any thoughts. Also from the pictures and your statement that there are 5 emitters I am wondering if they are being fully saturated. From the pictures, it doesn't look like is the baskets are getting the spray but I am sure that is because you have the lid up, although you say the pressure is lacking. I know that with areoponics it is important to fully saturate the root system and most people overlook this because with each emitter they loose pressure. With one row of emitters down the center the outside of the baskets wont be getting the solution. If I understand correctly you are also using a drip system that should offset that problem.

I guess, through the possess of elimination I would want to look at the nutrients. You may want to look up the pepper plant pH level, I kept my Bell peppers at 6.0 but yours might want something different if they are different type. At this point, because of your problem I would want to change the nutrients each week until I was able to learn more (just in case). That amount of nutrient solution for those small plants you could cut back to about 4 gallons of solution if cost is a problem, and if you have that ability? Also more frequent nutrient solution changes cuts down on algae and bacteria problems having the time to grow. I had a similar problem years ago with a single strawberry plant, I had growing in grow rocks. I never checked the pH because I didn't have a tester, but I don't think that it grew at all in a month that I gave it a shot. I was using dry mixable nutrients (I don't remember what kind). If the system is not light proof then algae and bacteria will be a problem.

I am looking for pumps that will support something like 24 to 48 emitters minimum.
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Old 07-03-2009, 10:58 AM
JD4x4 JD4x4 is offline
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I came across some misters that I'm using in my outdoor soil/container garden which use 10 gph (38 lph?) each, and they have nice varieties of patterns available. At 50 psi regulated hose pressure with a 10 gph restrictor their green full-circle spinners will spray about a 7 foot circle, so way lower pressure and/or flow shouldn't be an issue I'm guessing. They have some other non-spinning fan nozzles that also do well on low pressure/low flow.

Made by MisterLandscaper and they are sold in the US at Lowes stores. I don't know if that helps anyone, but I am going to try them when I build a small aeroponic system.

My outdoor soil green & red sweet peppers are slow growing as well & I have just transplanted them into an outdoor ebb & flow to see if they speed up any. My other soil plants (tomato, cucumber, yellow squash and a banana pepper) have already started producing.

Last edited by JD4x4; 07-03-2009 at 11:02 AM.
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Old 07-03-2009, 10:36 PM
GpsFrontier GpsFrontier is offline
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I had read somewhere a while ago about the misters/emitters used in aeroponics and that the water droplets that came out needed to be within a certain size range to be effective. I don't know how correct that is but any emitters designed for areponics should be fine. Although while trying to find out more about that particular issue with areponics I have found some good information on aeroponics and I just thought I would post the link to it for anyone that was interested.

Aeroponics - Wikipedia, the free encyclopedia
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Old 07-03-2009, 11:11 PM
GpsFrontier GpsFrontier is offline
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I still need to find out more but here is a little bit that I just copied and pasted here

"The key to root development in an aeroponic environment is the size of the water droplet. In commercial applications, a hydro-atomizing spray is employed to cover large areas of roots utilizing air pressure misting.

A variation of the mist technique employs the use of ultrasonic nebulizers or foggers to mist nutrient solutions in low-pressure aeroponic devices.

Water droplet size is crucial for sustaining aeroponic growth. Too large of a water droplet means less oxygen is available to the root system. Too fine of a water droplet, such as those generated by the ultra-sonic mister, produce excessive root hair without developing a lateral root system for sustained growth in an aeroponic system.

Mineralization of the ultra-sonic traducers requires maintenance and potential for component failure. This is also a shortcoming of metal spray jets and misters. Restricted access to the water causes the plant to lose turgidity and wilt."
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Last edited by GpsFrontier; 07-03-2009 at 11:16 PM.
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Old 07-04-2009, 10:40 AM
RedHerring RedHerring is offline
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I'm thinking it might be a light problem. I added another "daylight" tube a few days ago and things seem to be looking up. I'll see if I can find some more light sources around. Is there a possibility of adding too much light? They're all relatively efficient light sources, not generating much heat or UV, but can there be too much of a good thing?

I didn't really know that the water droplet size made that much of a difference. I can't really get new sprayers so the ones I've got will have to do the job.
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Old 07-04-2009, 06:10 PM
GpsFrontier GpsFrontier is offline
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Quote:
Originally Posted by RedHerring View Post
I'm thinking it might be a light problem. I added another "daylight" tube a few days ago and things seem to be looking up. I'll see if I can find some more light sources around. Is there a possibility of adding too much light? They're all relatively efficient light sources, not generating much heat or UV, but can there be too much of a good thing?

I didn't really know that the water droplet size made that much of a difference. I can't really get new sprayers so the ones I've got will have to do the job.
That quoted statement was really talking about a true aeroponic system, where there is no growing medium at all. With your system because you have the baskets with the grow rocks I don't see the water droplet size would be a possible problem until the roots start hanging down from the baskets and are in direct contact with water droplets. I Would just want to make sure that the growing medium in the baskets is getting fully saturated.

I ruled out lighting because I thought that your control plants (plants in the soil) were getting the same lighting and doing fine. But if adding the light seems to help you might be on the right track. I am not real familiar with lighting issues because I use natural light right now. Although I cant remember anyone ever having a problem with too much light unless they were talking about the wrong lighting or too much heat building up and cooking the plants.
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Old 07-24-2009, 07:47 AM
nilsen nilsen is offline
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Quote:
Originally Posted by RedHerring View Post
I'm thinking it might be a light problem. I added another "daylight" tube a few days ago and things seem to be looking up. I'll see if I can find some more light sources around. Is there a possibility of adding too much light? They're all relatively efficient light sources, not generating much heat or UV, but can there be too much of a good thing?

I didn't really know that the water droplet size made that much of a difference. I can't really get new sprayers so the ones I've got will have to do the job.
My System also uses a sprayer and it seems the hydron clay balls were being staurated just fine, I wouldn't worry about that.

As for the lights, I had a 125W CFL "blue" spectrum for growing and it just didn't cut it for about 6 plants, I added 4 smaller bulbs, 2 RED and 2 BLUE (normal CFL's) and the change was immediate. The plants just shot up. Was great.

Cape town, Nice man, I'm From Durban.

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