The capillarity of 3/8" stone is higher then 1/2" stone but, since you are using mulch, I'm not sure this is important.

It would be if you are counting on getting water to the plants through the stone.

cleaner? and you plan on using dirty mulch too? doesnt that defeat the purpose of being clean,or what do you mean by clean?

personnaly smaller stones are better since they allow more surface area for roots and beneficial bacteria and water to cling to.

Hi Grampe,

Utsharpie's advice above is correct. A good hydroponic garden that uses a growing medium is far better off using a medium that is completely inert, i.e., contains no nutrient. Using mulch, whether bark chips or lawn clippings defeat the purpose.

Now for the size of the medium. This depends on how you are going to operate your garden. I use coarse sand with the fines screened out. There are a few 3/4" stones in it but that does not bother me. The average sized particle would be a bit less than 1/8", which means that I can plant most seeds directly into the medium, which would not be possible with 3/4" stones. Frequently, one needs to dig into the medium with ones fingers ... which is much easier with coarse sand than with larger sized gravel.

In effect, it boils down to how you wish to run your garden. I invite you to see my site below for more ideas.

Jimr007

Here is a link that might be useful: Simple Sand Hydroponics

Thanks Jimr007 for replying to my post. I tried to respond to your
Simple Sand Hydroponics, but the page was forbidden, can you send me an email. my address is posted on my page, Thanks, grampe