A long-standing problem in the area of organolithium chemistry has been the need for a highly reactive Li–metal source that mimics Li–powders but has the advantage of being freshly prepared from inexpensive and readily available Li–sources. Here we report a simple and convenient activation method using liquid ammonia that furnishes a new Li–metal source in the form of crystalline Li–dendrites. The Li–dendrites were shown to have ca 100 times greater surface area than conventional Li–sources created by prototypical mechanical activation methods. Concomitant with the surface area increase, the Li–dendrites are 19 times more reactive than Li–powders which are currently the industry standard for the preparation of organolithium compounds. These features were leveraged for the reproducible synthesis of organolithium reagents over a range of common laboratory scales.