Backyard Aquaponics
A place to discuss aquaponics

I've got a bunch of sweet potatoes in the ground as well as putting a bunch of rooted vines into the AP system not too long ago. My main worry about large root crops in the gravel beds is more for the beds themselves than for the roots. I've heard of people putting potatoes into hydroponics and having them bust the bin open as they grew large and the gravel didn't get out of the way so the growing potato just deformed the storage bin grow bed till it bust. I expect that the half barrels the long way are a good way to grow large sweet potatoes since when they push the gravel aside, it will slide up the curved bed rather than busting it out.

As to the wetness issue, sweet potatoes like it wet at least for all early stages of growth. It is only shortly before harvest that too much moisture is likely to trouble them. Or if it is too cold I suppose the sweet potatoes might be more prone to rotting.

I expect that with many of the root crops, the time you need to worry about too much moisture is as the roots are filling out and nearing harvest.

I found that onions did well so long as they were not set deep in the gravel. Only the very bottom of the onion set needs be in the gravel.

I haven't had much luck with beats yet but it was too hot by the time I planted them. Will try again when it cools back down here. Same situation with carrots.