Hi JP,
I can't specifically answer your question, but here are a few things to consider / try;
put a small airstone in the bottom of the bottles of water to aerate the solution. Alternatively, you could just replace the water once a week.
add a small amount of soluble fertilizer to the water so the plants have something to grow with.
top the plants to promote root development and stronger stems.
If you're going to plant them in dirt anyway, go ahead and put them in some potting soil now.


The plants will appear to be growing fine, but they are in fact trying to find a food source. eventually the plants will get leggy, pale, and all around sickly as they use up their energy reserves searching for a new food source. best to not let them look too long.

I second grizzman's opinion here.

They are definitely looking for food. My pepper plant seedlings were rocking along, doing well. One day, i got down to check on them, and i find massive root growth in all directions sticking out of the rockwool cubes. It was time to move them to the hydroponic system. Once i did, root growth slowed to almost nothing, and the plant is focusing on throwing out foliage. Those roots are doing something along the lines of 'I swear there was nitrogen RIGHT THERE last week....'

Plants may survive in just plain, stagnant water for a period of time but the question is: for how long? That's something uncertain because growing plants need enough oxygen and nutrients to grow. Unfortunately, stagnant water won't be able to supply the sufficient amount of oxygen plants need and yes, grizzman is right that the plants will -- later on -- look for some food (nutrients) to eat.....

They can survive for years if you only do partial water changes. Let tap water gas off for 24 hrs before doing pwc. Trim roots if they start to fill container.

You`ll be lucky if they last a month in plain water, the first thing you`ll notice is the bottom leaves yellowing before falling off as the plant starves to death.

hex...plants can live for many years in just plain water. Its because of the anarobic bacterial action in the water. Just keep pots filled with water and only do partial water changes.

Plants need a supply of essential elements, N,P,K,Mg,Ca,Fe and micro`s without them they will become deficient and starve. Plain water typically contains Ca, some Mg but not nearly enough N,P or K. I recommend you do a side by side, one plant in plain water, the other with nutrients :) ..

You can add a little milk to water if you are concerned about nutrients. Tip: If you are using so much fertilizer, milk, etc. that you can see it in water....You are on the borderline of using too much.☺

Probly to late for an answer but look into the kratky method,just keep your water level so it only covers 20 percent of the root mass to ensure there getting enough oxygen,people grow this way without airpumps or airstones

some good info here http://growww.weebly.com/hydroponics.html