References in "Bio-Dynamics" Vol. III No. 1 (The Bio-Dynamic Farming and Gardening Association, Inc., 1943):
"potatoes are aided by [...] dead nettle (Lamium album)"
"all vegetables are aided by the following in small ratio, as in border: dead nettle [...]"
"all vegetables are aided by a border; that is, a relatively few plants of dead nettle"
So it sounds like planted here and there and especially around potatoes, dead nettle could be a useful addition, though its unclear how exactly.