Question

[Tim N]

Could someone please tell me some of the plants/vegetables that their roots need to be submerged in water 24/7? And ones that need to be in flood and drain system.

thanks in advance.

 

TN

[George]

none that I know of need submerged roots

nearly all plants will grow in flood and drain

You might want to look at the media and raft groups - also many forum topics already 

[Tim N]

Thank you George!

[Alex Veidel]

24/7 like for continuous flow systems? Watercress is one I think...

[Tim N]

Alex

I have set up two of my grow beds so that the water level stay the same all the time (to the surface of my gravels), water would drain out through a 1" pipe if it gets any higher 

[Sam Burton]

The key is oxygen to the roots.  If the plants are in DWC you need to put air stones, or similar, in.  In a constant flow like you describe, the water needs to turn over at a quick enough rate to keep the water oxygenated.  Some plants, like peppers, hate wet feet and require lots and lots of oxygen if you keep them submerged.  It's better for me to grow them in wicking beds.

[Tim N]

Cool. Thanks for the info 
 
Sam Burton said:

The key is oxygen to the roots.  If the plants are in DWC you need to put air stones, or similar, in.  In a constant flow like you describe, the water needs to turn over at a quick enough rate to keep the water oxygenated.  Some plants, like peppers, hate wet feet and require lots and lots of oxygen if you keep them submerged.  It's better for me to grow them in wicking beds.

[George]

You might get some algae if the surface of your gravel is damp, also more evaporation.  Dry surface is generally recommended.  

[Robert J]

I agree with George on the dry surface, only exception is when direct seeding to a flood and drain.  When I direct seed, i'll sprinkle twice a day until I have two primary leaves on most plants then let the system take over.  And as George points out you will get algae--but if you have red wigglers in your beds, after you quit watering the top, they will take care of the algae.  I have not found any plants so far that don't seem to like the flood and drain approach.  I've tried a lot of different tactics in my hydroponics systems and in all instances, the plants seem to go where they need to.  I would suggest googling "kratky method" and reading some of that material.  The only time I've found it necessary to use bubblers is when using floating raft systems with static water.  My flow through rafts using water thats been through lots of media do fine without bubblers.