  Using the link surgery formula for Heegaard Floer homology we find a spectral
sequence from the lattice homology of a plumbing tree to the Heegaard Floer
homology of the corresponding 3-manifold. This spectral sequence shows that for
graphs with at most two "bad" vertices, the lattice homology is isomorphic to
the Heegaard Floer homology of the underlying 3-manifold.
