I could be totally wrong on this, but I am going to say no it won't kill them. The reason I say this is because I have live plants and I have aquarium salt in my tank, so far the only thing that has killed any of my plants were the goldies
There could be certain types of plants that are sensitive to salt, I really don't know a whole lot about aquarium plants.
What types of plants do you have? Mine are arrowhead and amazon sword, salt did not kill them.
Jessica