  We describe a method for recursively calculating Gromov-Witten invariants of
all blowups of the projective plane. This recursive formula is different from
the recursive formulas due to G\"ottsche and Pandharipande in the zero genus
case, and Caporaso and Harris in the case of no blowups. We use tropical curves
and a recursive computation of Gromov-Witten invariants relative a normal
crossing divisor.
