Culturing Grindal Worms on soil free substrates

by Barry Cooper

Shown here is a variation on the methods that have been used for culturing Grindal worms on artificial substrates, which avoids the use of soils and allows harvesting of cleaner worms. The technique also avoids long-term compaction of the substrate, as occurs with soil-based material.
This substrate is a poly pad, sold in stores as filler for cushions, etc. I use it in place of the green "scrubbies" that have been recommended by others. It is 1" thick and cut to fit the shoebox. The pad is rinsed, then placed in the shoebox with enough water to keep it damp. It is important not to use excess water, as I have found that the worms will die off if I do. I change water in the cultures infrequently, going weeks between changes. When I do so, I can drain off about 6 oz (180 ml) from one shoebox, which gives a measure of the amount of water I use. In a set up culture there is barely any apparent free water in the bottom of the box. The box needs a lid to keep the humidity high.One or two pellets of food are added, onto which an inoculum of worms is placed directly. The culture is covered with a piece of plexi or glass and fed sparingly until the culture begins to flourish. It takes some time for the culture to become established and productive, so be patient. The pellets of food seen here are a high quality kitten food, which I use to "gut load" the worms with vitamins and protein. I feed mature, productive cultures about 10 pellets of kitten food daily. This culture is a "young" one, and now yields about twice the quantity of worms seen here every day. Worms are harvested by lifting the plexi sheet, then washing off the worms adhering to it. I wash the worms into a container, then rinse them to remove soluble organic matter. Then, with the worms in a small amount of water, I draw them off using a baster. By doing this I can leave behind residual cat food, so avoiding putting it in the fish tanks.