Growing Things: How do I get rid of this pest on my spinach?

Q: I planted my spinach in the fall, which I have done with great success in the past. Unfortunately, that success has failed to materialize this year. In addition to bolting very early, my spinach has fallen prey to leaf miner. I removed the affected plants (all of them) and put them in the garbage, not the compost bin. I have just replanted but don't know what I can do to avoid a repeat of the unwelcome visitors. I have both horticultural oil and Safer soap. Will either of these work and if so