Level 37 has two goals: acorns and gnomes. The level itself can be split into two stages: collecting the acorns and collecting the gnomes. Since level 37 is a hard one, the first stage should be completed with as few moves as possible. Try to make matches hitting as many acorns as possible.
As soon as you get at least half of the required number of acorns, switch to the gnomes: one large in the bottom, two tiny ones at the top. The layers of grass concealing the small ones is rarely worth clearing in the beginning. Instead, focus on the tiles covered by grass. It’s best to try and create as many power-ups as possible, as they are extremely helpful in saving moves. The remaining acorns will be easily cleared by explosions and matches aimed at the gnomes. Remember that by using multiple power-ups at the same time, you charge your Rainbow Blast faster.