It takes approximately the same amount of time for (nearly) all the worms to migrate into the material on top of the screen as it did for the initial layer of bedding now beneath it to be ready for harvest. For most folks this is between two and four months. It is the one down-side to the forced-screening harvesting method; it takes a while to get your first batch of finished material.

As to what do to with the castings once they are harvested, first and foremost, know that TEA DOES NOT REPLACE CASTINGS. Research shows that the most broadly beneficial and long term impact is produced by applying the castings themselves directly to the soil. In established garden plants this is accomplished by covering the soil inside the plant's dripline with a 1/4 inch layer of castings and scratching it in, or by spreading the castings 1/4 inch deep inside the dripline, then covering them with a layer of the organic mulch of your choice (compost, grass clippings, shredded leaves, etc.). How often to do this depends on the characteristics of the castings, the plant and its needs, your soil type, your climate, etc., etc. Some apply castings only once during the growing season, others monthly. The variables are too numerous and the research too scarce to be able to make definitive statements. This is your opportunity to do your own experimenting and see what works best in your particular situation!

Kelly S