Unfortunately, no, there isn't.
This is because there is no way of breeding Pokemon that guarantees that all 6 IVs pass down to the offspring, and since Hidden Power is determined by IVs, you can't do it.
Just keep breeding until you get one with the Grass-type hidden power.
And as a side note, it is probably better to either have Grass Knot or HP Electric, or to just go with the standard Surf/Ice Beam/Extrasensory/Dark Pulse (or U-Turn).
EDIT: there is! Just look at this question.