What's good on a raft?

[Louise]

I've got the cut-off top of my IBC fish tank, to use as an extra grow bed. For plumbing reasons, it seems easiest just now to use it for a raft culture rather than a media-filled one.

Question is - what plants enjoy being on a raft?

I have some squash/pumpkin plants that need space somewhere, but I assume they are too big for a raft, or not?

Lettuces?

What else?

[sticky]

Sweet, I came looking for the same thing. I just got done erecting some 4" pipes to use as a deep water culture. And i was curious was plants would be good in that short of set up. I have a bunch of lettuce plants ready to put it but i have 3 pipes at 9 ft each. Seems i might have a little extra room. So if anyone can recommend some good DWC plants, that would be awesome.

[Alex Veidel]

What plants enjoy being on a raft? Huckleberry's :) Mark Twain penned a lot of that character's time on the river.

[Louise]

Funny! But I'm surprised we're not getting any real answers to this.

I had some low styrofoam boxes with holes in the bottom, for drainage. I made this little experiment, but it's still too early to know if it works: I put a thin piece of textile over the bottom. Where there were holes in the box, I pushed the textile down a bit and a piece of crumbled tissue paper - I didn't have any of those net pots, and couldn't be bothered to find out where to get them. In the tissue paper I placed some seeds, and just to see if it works, also some seeds I planted just loose on top of the moist textile. What I sowed:

Portulaca oleracea, Common Purslane

Carrots

Beta vulgaris, Swiss chard/silverbeet

Valerianella locusta, corn sallad

[John Cubit]

I am growing Chard in a raft/net pot.  It is out growing what is in actual soil garden.

[sticky]

Yea, but isn't that basically another lettuce. Maybe not in the same family, but very similar in plant type. From what i have observed is that certain plants need to get air to the roots. So a DWC set up wouldn't facilitate that, i guess the real question is what plants will grow well in those condition.

[John Cubit]

Sure if you concider my lettuce is only 6" tall and the chard is 13".  Other plants I have placed in the DWC that did well were, habanero seeds, pole beans, snap peas, leaf lettuce and broccoli.  All of these have been moved to dirt for the season and did very well through the seedling stage and have survived the transplant to soil now with 2 months in the ground.

What did terrible or nothing in DWC - Beets, carrots, potato eyes, spinach, tomatoes, cumin, red cabbage and my kale.

As for oxygen.. I keep all the pot only submerged 1/2" of a 4" deep pot.  The chard roots extend nearly a foot but have a very healthy ball not in the water.  I also have a perforated air line in the trough I am growing in forcing additional air in the water and to keep the nutrients moving to the other end.  I also have a healthy population of red worms and Springtails in the main bed as well as Springtails nesting in the net pots.

But like I said I only have Chard in there now.

sticky said:

Yea, but isn't that basically another lettuce. Maybe not in the same family, but very similar in plant type. From what i have observed is that certain plants need to get air to the roots. So a DWC set up wouldn't facilitate that, i guess the real question is what plants will grow well in those condition.

[R.K. Castillo]

Are you doing any type of filtration before the fish tank water goes to the raft?  What's going to act as the bio filter to grow the bacteria?  

As for plants, it seems like lettuce & herbs do great in a Raft System.  

[John Cubit]

Not in the sense we are all use to.  Let me explain the process that is working now for me.

Fish tank with pump pumps up to main grow-bed that is a flood and drain.  10 minute fill 30 second drain.  Filled with Hydrocorn.  This drains back to the fish tank directly.

I added a T to the line to the grow-bed and divert a small amount of the water to the troughs. The grow-bed if on full, would fill at 45gph.  With the T and a diverter valve I can send 1gph to each trough.  I added a stand pipe in the trough that limits the depth of the water to one inch.  Baskets are all 1/2" above bottom and 1/2" submerged.  Each pot is filled with Hydrocorn it came from my established bed.  So bacteria is in each pot and established.  Now the net pots are actually home made.  I get the empty starter packs that you buy plants in, use an old glue gun and place equally spaced holes in them so water can pass through and roots can grow out of them.

Solids get caught in the pots as well as nutrients flowing past the roots, the hydro wicks water and any solids will pass by and go down the drain back to the fish tank, passing through filter sponge that I change once a month to get any large particles out of the water. I use those in planters/clay pots and new test beds.

With the pump volume most solids go to the main flood and drain bed.  The real downside is that I had to add couplers and clean the valves at least monthly or check the weekly, because solids do quickly mess up the flow rates once they build up.

[Louise]

I'm letting the media grow bed filter the water from the fish tank, then from the sump tank it goes to the raft tank before returning to the fish tank.

Why is clearing the water so important in DWC?

The bed I'm currently using for rafts could just as well be another media bed, but then I'd have to work some more to get the balance right between the in flow rates and  out flow rates, and get the annoying bell siphons to work. With the rafts all I need is a simple standpipe. I probably will put media in it eventually, but for now it's an experiment raft culture.

R.K. Castillo said:

Are you doing any type of filtration before the fish tank water goes to the raft?  What's going to act as the bio filter to grow the bacteria?  

As for plants, it seems like lettuce & herbs do great in a Raft System.  

[R.K. Castillo]

You gotta clear the water so the roots don't get all gunked up with the solids and get root rot.  

Louise said:

      Why is clearing the water so important in DWC?

[Alex Veidel]

Yep, that's why. But if you run the water through your media bed first, that should work fine. You just need a way to get rid of the solids and the media bed works perfectly for that.

R.K. Castillo said:

You gotta clear the water so the roots don't get all gunked up with the solids and get root rot.  

Louise said:

      Why is clearing the water so important in DWC?

[Jason A.]

You can pretty much grow anything you want in a raft system as long as you provide support for the plant and it doesn't become to heavy and push the raft under the water. Lettuce, basil, tomato, cucumbers, peppers, kale, squash, pumpkins, watermelon to name a few.

If I were going to try and grow something like watermelon, pumpkins or any plant whos fruit grows on the ground I would probably make my rafts no more than 2ft wide and 2ft-3ft deep. Plenty of room for the roots and since the raft bed would be narrow it would be easy and simple to allow the plant to grow its fruit on runners along the ground beside the bed.

You have to pre-filter your raft water otherwise you will have root issues like others have mentioned.

Also when growing in raft systems/DWC you DO NOT provide any amount of space between your roots and the water. You want your net cup bottoms submerged at all times. Reason being that sometimes when plants have that air gap between the roots and the water your roots will begin to twist which makes your plants inefficient at using the nutrients in the water. 

Hope that helps

Have a great day