Crane flies, or daddy-long-legs, lay their eggs mostly in grassland and lawn and not in well cultivated ground. If the beds wre made with sods of grass in them, the leatherjackets would migrate to the surface but this will be a once-off occurrence.
If leatherjackets are going to be present this spring, they are already there and digging will find them. If you find none, problem solved. If you do find them, just tdig the soil over a few times to expose them to birds.