Kiddie pool or an old hot tub?

oh no... its going to be like 20' x 20'.. so I need a liner material...

Since the effectiveness of such an approach is highly questionable for a number of reasons, it would seem logical to first construct it on a small scale such as the kiddie pool mentioned above. That way there is minimal expense on what may well prove to be a problematic method of gardening. If it does work then it gives you a prototype to debug before making a major investment.

Dave

Without knowing exactly what you have planned, it's impossible to say.

kevin_kiss - one challenge I foresee is that your method would water everything in the garden at once, whether it needed it or not. Unless the entire garden was growing a single crop I can't see this being very successful. I also can't quite see how you are going to get the water into the garden evenly. If it enters at one point won't it wash the soil away at that point before it has permeated the whole bed? Or were you thinking of having the whole bed inside a second container and filling that with water, much like placing a seed tray in a water tray?

If you do go ahead, butyl pond liner lasts a very long time (ie decades) and is stretchy so it can cope with a few lumps and bumps underneath.

The whole depth of the garden will be like 2 feet at most.. and it will have a corrugated pipe in key spots so water can get in and out for even watering and draining... worst case I have a large garden that I can drain out excess water real quick...

Regardless of the depth you are asking for trouble if the drainage is poor. The concept of a raised bed garden is to promote drainage and your proposal is contrary to that.
There would be ways to utilize your pool that could complement the garden. You could use it as an irrigation resorvoir or you could remove the bottom and use side walls to create a raised bed. I'm afraid that even blocking soil drainage partially may lead to root zone issues.

I really don't understand why you would do this. Drip irrigation is the simple choice for you...

Are you recycling the water time & again? That is the only reason I can see you wanting to try.

yes I will hold the water in tanks.. and from time to time put fertilizer in it.. I had drip irrigation before.. I don't like it.. I have to setup main lines.. tons of feeder lines.. then rip it all out at year end.. this way.. I flip a switch water is pumped in, everything is evenly watered and I then drain out..

Cool idea..I would lay your drip lines on top of the liner (for even water) then i would fill it with 1/3 peat moss 1/3 manure and 1/3 top soil. The peat moss will wick up the water everything would be nice and loose. Every fall add organic material and I would think for 20x20 garden add 3 bags of peat moss $25 worth till it in and you are set. I would think once the soil is moist it will be easy to keep water in the root zone. Good for you let us know how it works out.

So as Flora said everything gets watered at once whether it needs it not? Different crops have different water needs. Different crops have different root depths and shallow rooted plants would never reach that deep for water.

Then there is the issue of gravity and the effect it has on water dispersion to overcome. And the issue of compacted soil, plugged drainage holes, stagnant bacteria laden water, etc.

You might want to do some research into the problems associated with "bog gardens" as that is basically what you are trying to create.

Experiments are great. A good way to learn. But they can be expensive in more ways than one and you still has to take into consideration some of the basic laws of physics like water will only flow up and disperse up and out only under pressure.

Dave

No....soak every thing from the top to start...then you can start pumping through your drip lines and the moisture will work it way up like peat pellets do. stick your arm into the soil and you can tell how wet the soil is...start out with level ground and your drip line evenly distributed...if you have a bed 2 ft deep I dont see a reason why this wont work.

I guess I need to fully explain, since I get the feeling some people have different vision of what I'm building in their heads.. so here goes..

I have a sloped back yard.. so the one edge of the garden will be slightly above ground level.. like 6 inches.. then the rest will be more and more above ground. The back end will be totally above ground and have a drain tube that heads down the hill into the water tanks.. the whole garden will have a sloping pitch to the bottom of it and 6 inches of gravel and corrugated pipe leading to the drain. The grave and pipe will be covered with geotextile fabric so only water gets through it.. and there will be some corrugated pipes running vertically around the garden to help with drainage and filling.. So it will be rubber membrane, 6 gravel, fabric, 24" good soil. So my plan is normally when everything is fine with the weather to just have the drain open and water will just flow out.. so there is no chance of water logged soil.. then in hot summer when there is no rain.. fill and purge the garden when needed. It would just act as if we got a good rain. The whole system will be gravity drained and water will be pumped back in when needed.. I see your points as to some plants needed more water than most..A good point to consider.. but does this explanation give a better understanding of what I'm trying to do.. ?

thanks for the remarks so far..