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Dying plants in Autopot-like system

Posted by ezmac NY (My Page) on
Tue, Aug 26, 08 at 18:30


I am new to hydroponics; I am using the Smartgarden system from Futuregarden, which uses the SmartValve to regulate nutrient delivery to plants. I am growing in a mix of perlite and coco coir.

After a few weeks of good growth, some of my plants (thyme, cilantro, melon, rosemary) have leaves that are wilting and dying. The thyme is almost dead--its top leaves started wilting first, and now it is spreading to the rest of the plant. The other plants in the system (peppers, dill, basil) appear to be healthy.

Does anyone know what the cause could be? I am seeing some salt accumulation on the surface of the coco coir; perhaps I should reduce the nutrient concentration (I am using full-concentration right now)?

I do not think there is a mold or root rot problem, as I don't see or smell anything funky in the reservoir.

Thanks for any help you can provide.

Follow-Up Postings:

RE: Dying plants in Autopot-like system

  • Posted by rebecca3 basement and sodium (My Page) on
    Sun, Aug 31, 08 at 13:54

I'm also new to hydroponics and am having a similar problem. The yellow squash are doing great in the Aussie Autopots, the tomatoes are wilting and dying.
I have three different systems, an Australian Autopot with six pots, an English Autopot with 2 pots, 4 Eco pots, and a Green Machine PVC Pipe Garden. I also have an Emily's garden, but that is more of a toy.

The green machine is loved by it's plants, so far.

The tomatoes in the autopot are drooping, have ceased growing, and their leaves are turning under and becoming a bit purply underneath. I have read the info about pottassium, but am unsure how to go about getting more potassium into the tank.

Do I drain everything, then change the nutriens? Since all the nutrients have some form of pottassium, which do I choose?
What's the recipe????

RE: Dying plants in Autopot-like system

If the leaves have purple patches, it could be a shortage of phosphor.
 pictures please

Forgot to mention . . .

Check the roots of those plants that are dying. The roots should be white. If not . . . you may have problems in that area (not enough oxygen, too much water, rotting, etc).

RE: Dying plants in Autopot-like system

What nutrients are you using? I have found that using the GH calculator on their website works. For autopots you should be using the "run to waste" concentration. "Full concentration" is variable. There is a different concentration recommendation for different plants and systems for most nutrients. Herbs should have a lower concentration anyway. They aren't usually heavy feeders. If you have "full concentration" the nutrients are just sitting in the medium until used while the water is getting sucked up or dried out. The salts you are seeing are visible evidence. See, if the water evaporates it leaves the excess fertilizer behind. (I try to minimize this evaporation by putting a plastic cover I made over it. You can make one out of a black garbage bag and tape it down. Just leave easy access for just in case.) The same thing happens further down in the medium as the plant uses only what it can. Eventually you will experience a buildup of fertilizers throwing the coco EC through the roof while your reservoir may read the right amount. Try leaching the coco coir and reduce the concentration. Also, check your pH. Try to aim for perfect since that is the best way to get the plant to uptake nutrients. Bad pH equals bad nutrient uptake.

I didn't read any of this anywhere else. I have discovered this (building EC in coco) through trial and error and a little logic based on observation.

RE: Dying plants in Autopot-like system

Thanks joe for your reply. I've been using the "Liquid Earth" brand two-part nutrient, b/c it came for free with my setup. I checked the GH website and it seems they're a lot more precise about helping you figure out the right concentration for you. Maybe I'll buy their product instead.

Incidentally, how would you recommend leeching out the salts? I've got my plants in square plastic pots that can be lifted out of the tray that holds the nutrient, but a couple (tomato, melon) are vines that I think are prob. best not to disturb too much. I was thinking i could just pour a bunch of pure water right on top of the coir, and let it run down into the tray, and then just suck off the diluted nutrient that's in the tray. What do you think?

Also, the plant trays get kinda hot during the day--they're sitting in a southern-facing window sill. could that be a problem?

And if the water in the tray smells a bit funky, is that normal for these hydroponic setups? I put some peroxide in there, but the smell is starting to come back... prob some mold or something growing in the nutrient.

Sorry for the all the questions--I'm new to this stuff and hate to see my plants dying!

RE: Dying plants in Autopot-like system

I would use a leaching solution. I can't think of the names of those out there right now. I use GH's type. Got a wet/dry vac? That will help suck the nutrient out without having to move the pots. I used a hand siphon. Took a little while. That funky smell is a little hard to identify on the internet. Some smell is normal. A rotting smell is only normal in bad situations. Like drowning rotting roots. You might let your substrate dry quite a bit before leaching. Also, oxygenate the water as best you can. As far as heat, how hot are we talking?

RE: Dying plants in Autopot-like system

Hello--I'm still having problems with my system, and could use some help.

I bought leaching solution (clearex) and soaked every one of my pots with about 1.5 quarts of water, drained it, and added fresh nutrient to the reservoir. My melon vine is doing awesomely--amazing roots and starting to flower. My lettuce also looks good, as does my dill But the basil died, the thyme died, the cilantro died, and the parsley has leaves that are curling up. And my hot pepper plant has drooping leaves, some of which have fallen off.

I can't figure out what the problem is. I don't think it's root rot (the melon roots are really impressive); there is a bit of a funky smell about a week after changing the nutrient, but it's not massive anymore (i cleaned all the trays out with a light bleach solution). Could it still be that I have too much salt in my growth media (coir)? Should I leach again (I did it two days ago)?

Also, temperature in my apt gets up to about 92 degrees in the daytime... Maybe that's messing things up?

Thanks for any help you could provide.

RE: Dying plants in Autopot-like system

Flush the system with fresh water (PH adjusted with some Hydrogen Peroxide) The H2O2 is very effective in controlling root problems. The plants might droop during a flushing, but will be back to normal once you introduced the nutes.

Flushing also helps the plant in using-up extra nutrients, and increase the taste (bric levels). I am however, not sure of the commercial leaching solutions. H2O is still the best and safest.


RE: Dying plants in Autopot-like system

I don't have my chart handy because I'm not at home where I've got all my stuff, but I wonder if maybe the feeding schedule that's good for some of those plants might be whats causing problems for the others.

Like tomatoes for instance - if you feed them enough to make them happy you'll probably kill peppers because they just can't take those concentrations of nutrients. At least that's what I remember.

92F is a bit hot, but those plants should do alright with that if there's enough water.

Also, check to make sure your smart valves aren't stuck. Make that part of your weekly routine - check each valve to make sure it works freely and consider taking the time to pull and clean each one.

If they stick in place they can make a mess of things.

RE: Dying plants in Autopot-like system

Rebecca3 - Please tell me more about your Green Machine PVC Pipe Garden. Vendor, pics, etc.


RE: Dying plants in Autopot-like system

Do you control Ph and EC? Do you have meters?

The problems could be multiple: too much food, bad Ph, nutrient too hot to hold oxygen, pythium.

Find and read carefully literature on hydroponic systems.

If you want help, we need pictures.

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