Continually i believe. I think some people even foliar feed with it? Im brewing tlo teas right out of the book. I use tea every other week and lacto on the in between week. The idea is: your tea gives the bacterial life your soil needs, and the lacto is an enzyme that speeds up the whole breaking down process. You can also use it on your compost heap to speed things up. Check this thread. https://www.rollitup.org/organics/663128-lactobacillus-acidophilus-anyone-2.html