I built up a second layer of gouache on the leaves and background.
Applied the ink and then let it dry.
Aaand
So! I learned my Canson mixed media boards are just paper lightly glued on a thick paperboard - not a thick paperboard. My gouache (Reeves) is super cheaply made with very little actual pigment. I should be more careful about leaving outline space. And I need to be sure to get an even application of ink for this piece, because the streaking does come through. Though that could be a cool purposeful technique to try later.
Time to try again soon, but I need to get my hands on some better quality gouache and different substrate