Anything that's scattershot is very broad and disorganized. Your scattershot method of planting a garden involves sprinkling wildflower seeds randomly around the lawn, rather than digging a flower bed and preparing the soil.
Scattershot comes from a shotgun that shoots small pellets in a wide range, rather than zeroing in on a specific target. It's used today for anything that takes that kind of haphazard, indiscriminate approach. A scattershot education might mean learning a little of this and that, instead delving deeply into one subject. And a scattershot response to a forest fire could be an ineffective attempt at quashing the flames here and there, rather than a deliberate, focused effort.