Things will grow even on nuke ground zero. Chernobyl had quite worse contamination than what a puny nuke can do, pound by pound of radioactive isotopes, and even the Red Forest is pretty green now, I was there and lived to tell the tale. Once you’re done with the short-halflife isotopes (couple days to few weeks), all you got to deal with are strontium-90 and caesium-137, which the ecosystem deals with fairly well.
The neutron-induced radiation is usually of pretty short half-life.
