You can use ANYTHING that is absorbent. I use three strips of BURLAP (Jute) rolled into long tubes. You can use a T-Shirt, frayed rope at both ends also works as wicks Pretty much anything that will absorb water-plant food.

THE FOLLOWING INFORMATION AND METHODS ARE TO NEVER BE COPYRIGHTED UNDER ANY CIRCUMSTANCES. Author credit would be appreciated - Pyx.

My set up.

I start with a 5 gallon plastic bucket. I use a NOTCHED (not slotted) 1 and 1/2 inch PVC 14 inch pipe down running down the inside of the bucket. The maximum height of the notch cut in the pipe is 1 and half inches. Then I add two inches of limestone gravel spread over the inside bottom of the bucket. Then I cover the gravel with a burlap circle I cut. And THROUGH small holes I also cut in the Burlap, I put the Burlap strips rolled into long tubes to be used as water-plant-food wicks. Water mixed with plant food is wicked by the burlap strip-tubes into the soil-less "soil" mix. This is what feeds the roots of the plants.

Above the Burlap/gravel, the next 8 1/2 inches I put a mix of 4 parts sphagnum moss to 1 part vermiculite to 1 part perlite soil-less mix. This is my planting "soil".

I sprinkle five or six heaping tablespoons of very some finely crushed egg shells for calcium into the soil-less mix. As the very top surface cover on top surface of the "soil" after transplanting seedlings into the "soil" are dark green plastic garbage bags cut or torn to fit very carefully around the plant stems. The garbage bags are used as a "mulch" to prevent water-plant-food evaporation.

Here's how it works...

The burlap strips rolled into long tubes wicks the water/plant food sitting in the limestone gravel into the "soil". The limestone gravel is used to retain the water mixed with plant food. The gravel acts as sort of a water table.

I use ordinary tap water that has stood in a separte bucket for 24 hours in order to de-gas chlorine. Then I mix Miracle Grow plant food in STANDARD RECOMMENDED amounts to one gallon of the water in a separate watering can for application down the down pipe for the plants.

That is it. I feed my plants every 10 days or so.

Some people may recommend drilling two 1/4 inch holes through the wall of the bucket at the top of the gravel (2 inches) as overflow holes, but I did NOT want to do this. My buckets have NO overflow holes. I water-feed using only what the plants need. I get pretty much NO loss due to evaporation.

I suggest you sprinkle the very first feeding immediately following transplantation of seedlings, across the top of the soil-less mix to very slightly dampen it.

All subsequent feedings are done through the PVC down pipe. Water to just barely cover the gravel. Let the Burlap wicks to the work for you.

The above system and methods works for me. Your Mileage May Vary. Use at your own risk. -- Pyx.

Here are some ideas:
http://www.insideurbangreen.org/sub-irrigated-buckets/page/2/

I can't find it but I saw one using a red 16oz. plastic cup with holes in it for the wicking chamber in 5 gallon buckets.

The 16oz plastic cup is used on www.globalbuckets.org.

I cut 4" PVC to fit between bucket bottoms, holes drilled, PVC section filled with same potting mix as container.

4th year.

Here is a link that might be useful: Here: