Some plants don't grow well in a wick system. The trouble with wicks is that the water transport is very limited, and plants such as lettuce, tomatoes . . (all those that need lots of water) . . will perish during a hot day (I speak from experience). The best plants for wicks are herbs.
As for your question: I buy a mop and cut off the strands, but the natural strands (cotton, etc) are no good. Get the rayon (pure white strands). They are the best.

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Thanks for the pics Greystoke. Are you saying that the amount of wicks you have used in the picture would not be enough to provide for a tomato plant? I was thinking one thick rope might be enough but it seems I have to reassess whether the idea is feasible altogether.

Yeah, I've tried wider pots and more strands, but it was useless. Another thing you must check is how high the strands suck up the water. In my case that was ± 120mm (5") max.
I still have a number of ornamentals and some herbs (parsley, etc) on wicks, but generally . . not on veggies.

Rafts will work, but there's a reason you don't see a lot of wick systems for sale or in use.

They just don't work that well. There's serious shortcomings as to how much water they'll lift and how far they'll lift it, which limits the size and type of plant you can grow, as well as the size of reservoir you can make use of. (A deep reservoir will be too tall for the wick to easily lift the water once it gets near empty.)

Tomatoes are thirsty plants. If you want something simple with a lot of capacity, look into Self Watering Containers (SWC). Even then you're going to have to water frequently when it gets hot and the plants are big. I built a large SWC for my mom. She's got two tomato plants in it and it holds somewhere around 5-7 gallons of water. It needs filled every other day at least.

I have used both wool felt and propylene felt strips for wicks. They don't move enough liquid for heavily-feeding plants.

That's a good point, I hadn't thought of that.

Passive hydroponics like that work best for plants that don't eat/drink much because the hungrier ones just starve.

I could be wrong, but with the exception of some herbs pretty much anything worth eating is going to really challenge a wick system to keep up. Veggies eat a lot.

So what would be a decent passive system for me to look in to? I am having an issue with the length of my wick being too long and it's just not working. My setup is a big plastic bin and 5 soil bags inside - sitting on a platform above about 6 inches of water. The problem is that if the water is down to about 2 inches, it has to wick up over 5 + inches to get in to the soil. I have a little pump setup to pump the water up, but I am looking for a simple backup 'system' in case the power goes out or the water level get's too low for too long (and the pump will not pump with 2" or less water).

Seems to me if the issue is the water level getting to low, it can be fixed by making sure it doesn't get to low. The easiest way I see is by using a float valve, like the ones used for swamp coolers (they sell at Wal-Mart for about $4) or toilet tanks. Hooking it up to a water supply with 1/4 inch poly tubing and quick connect fittings, then setting the float at a level where you get good wicking action. You can even run it inline with the RO water line if you wanted.

just add more wicks. the wick only takes the water to the lowest level of the soil. from there the water migrates up via capillary action.
do a search for water movement through soil in the container gardening forum for lots of education information on the subject.

I have had good luck using Tiki Torch wicks (only a couple bucks a pack) and perlite. Makes a very nice cloner.

Great suggestion artwk! I'm about to clone a bunch of coleus for my flower bed. I may have to try that.

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This post was edited by DaleRobinson on Tue, Dec 9, 14 at 10:42