Flushing nutrients / perpetual garden

plantboy_grower(9)February 13, 2008

I have been told that plants store nutrient salts, and the produce tastes better if these salts are used up before harvesting and eating. Yet I have also been told that although it will not taste as good, eating a crop that has not been flushed is "safe".

1) Do leafy crops need to be flushed like fruiting crops do?

2) What about a perpetual herb garden that would never be flushed? Or, how does the aerogarden get away with it, picking lettuce and mini tomatoes all the time?

3) Are there different nutrients out there, some safer than others for food crops?

4) I never gave a second thought to picking lettuce out of my outdoor organic garden, picking it as it grows. So what's up with synthetic nutrients, is there a difference here in when you can eat it? I have been told that nutrients are nutrients - whether they are broken down by bacteria (organic gardening) or whether they are directly supplied by synthetics/salts...

so I am failing to understand something here.

I am currently using the Technaflora line of synthetic nutrients on my first ever hydro crop:


5) Also the flushing process seems to be expensive - 8 tsp. (40 ml) of sugar daddy per gallon!

Thanks for your input!

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Plants take up what they need from whatever source, organic or chemical in the form usable. Eat it!

Flushing is expensive yes. Me thinks so much flushing is not so necessary a process but propaganda put out by the chemical companies to get you to buy more chemicals. Keep it in there longer, add water to replace what is used by the plants and test for addition of more chemicals or let the plants tell you when they need a boost.

Sure they are concerned with a buildup of chemical salts forming crystalline structures within the systems. That to me is a sure sign of chemical inefficiency. I'm still not convinced pure organic sources are not the best source of hydroponic nutrients regardless of the company propaganda and plan to set out to prove it to myself after seeing tomatoes grow out of pure concentrated human wastewater at a sewer plant.

    Bookmark   February 13, 2008 at 4:38PM
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Yea but at the sewer plant you probably had a lot of microbial life breaking down the material into plant-usable forms, right? That's the difference between soil and a sterile hydroponic system.

I'm sure it is possible though... not saying it's not.

    Bookmark   February 13, 2008 at 6:17PM
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I think it's bunk. Not bunk put out by the chemical companies to get you to buy more chemicals. It's bunk put out by the hippies to get you to use less. Regular osmosis will force your plant to expel any excess salts, provided your nutrient solution hasn't crystalized. I can't imagine anyone using enough fertilizer to cause THAT to happen.

Lastly, most salts taste pretty darned good. You won't taste them (if my single hydroponics experience with bibb lettuce is any proof), but if you did, it wouldn't be a bad taste. They're not like Lysol or anything. Chemicals rock.

(can you tell I don't grow things organically? :))

    Bookmark   February 13, 2008 at 7:24PM
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charlielittle: all I can say is that the grass always grew really thick over the septic tank when I was a kid, and it was really difficult to mow because it was so thick.

iliketoast: you should change your name to ilikechemicals. I suppose it's ok but I will continue to look into the matter to learn more.

Seriously you don't flush your lettuce at all?

    Bookmark   February 13, 2008 at 10:27PM
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Hey I didn't intend to start a chemical vs. organic war!

Yes active sewer contains microbes that make all the nutrients available to the plants and the treatment process of aeration provides the oxygen for the roots. If the churning sewer was contained below in the root zone I would have no problem eating what grows above as plants don't transmit pathogens from the roots to the leafy and fruit portions.

This brings to mind the e-coli tainted spinach in the news. It was undoubtedly contaminated by rain splash from the soil or direct contact from contaminated foliar sprays.

Back to the subject though. I plan to use chemicals in my patio hydro system and have no problem with them as such, just think excessive flushing and changing out entire reservoir systems every two weeks or so like I have seen written in various places is bunk. You don't need to flush any hydro system prior to eating any produce because the plants only take what they need from the solution to grow from whatever source.

Japanese have been using human waste in gardening for centuries but they know not to get it on the plant parts they eat. If your system were not covered and allowed to splash the plants with chemical salts, they would surely be unfit to eat because of chemical residue.

Yes I'm an old hippie...use less chemicals by being smart and not needlessly wasting them or dumping them out in places where they might do environmental harm! Use them wisely and they will produce as intended... On the other hand, if I can cause organic materials and methods to produce the same results without danger or likewise environmental harm, I will opt for organic.

    Bookmark   February 14, 2008 at 5:38AM
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Plantboy, I'm a chemical engineer. I doubt my position on chemicals will change :).

No, I didn't flush the lettuce, and because I know so little about hydroponics (I'm getting there) I fed them at 3-4 X the concentration you are supposed to. To be fair, I had nothing to compare it to other than store bought Boston lettuce, but the homegrown one was definitely better.

    Bookmark   February 14, 2008 at 9:16AM
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As I said earlier, I am told that the plant eats what it needs - regardless of how that gets to the plant (i.e. microorganisms in a medium breaking down organics into plant usable form, or, the food directly applied and available without microorganisms).

I would like to learn more about it though. I'm new to hydro also.

I tried my purple basil today. It smells good if you disturb the plant, but once the leaves were cut off they didn't have as good of a smell, and it kinda tasted like grass. However to its credit, I am told that purple basil is strong, and I've never grown it before - my fault for experimenting with hydro with a plant I am unfamiliar with.

I tried a few leaves of the lettuce and they taste really great :) I am going to run the system with just water and a LITTLE bit of magical and sugar daddy over the next 4 to 7 days (not sure how long i'll wait yet), then I will harvest. I mainly want to see if there is a difference for both the lettuce and the basil (as before technaflora had magical and sugar daddy, their instructions were to just flush with plain water ... but I'm still trying to figure out if they were talking only about fruits, or, leaves also, as of course I am only growing leaves right now.)

    Bookmark   February 14, 2008 at 1:33PM
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I've read about purging leafy veggies before eating them by simply running clean water through the system for about a week. does it work / help? I don't know. I don't do it.
I've also read for fruits (including tomatoes) you should reduce the amount of water they recieve as you near harvest as this will concentrate the sugars in the fruit. This is the same reason vineyards are grown on hills. so the grapes don't get too much water.
Regarding changing nutrient solutions regularly. I use an EC meter and continually add water and nutrient as needed to my system to maintain the desired concentration level. I only purge my tank every 4 to 6 weeks depending on the plant's consumption.

    Bookmark   February 14, 2008 at 3:17PM
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Yea I like what you're saying about only purging every 4 to 6 weeks based on the plant's consumption - sounds like saving $$$ to me :)

Yea I figure I have one week of nutrients / grow left with this lettuce/basil, then I will purge with either water only, or maybe a little bit of the sugar daddy / magical. I realized today that I should have left the lettuce as seedlings for 14 days / 3 leaves, instead of the 7 days they got, so I think I need to give them more time as it seems like the heads are really starting to form now.

So about 6 days from now I will purge for a few days. I did try some outer leaves today though and they were good on the lettuce - didn't care for the basil so much though.

    Bookmark   February 14, 2008 at 11:52PM
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I'd be interested to know if it affects the taste. Do you by any chance have two separate water supplies so you could purge some of the lettuce and not purge the rest?

    Bookmark   February 15, 2008 at 10:07AM
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I don't have that setup right now - I would like to do some growing in buckets or pots outside eventually, in which case I could flush one bucket and not another one. That's a little ways down the road yet but would be worth doing.

    Bookmark   February 16, 2008 at 12:10AM
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