Bush bean are a heat-loving crops. Soil must have time to warm up before they are planted or else the seeds will rot from sitting for a long time in wet soil.
We have vegetable planting times in a color chart and calendar: https://extension.umd.edu/hgic/plants/when-plant-vegetables-maryland
You can easily access them by putting 'planting calendar' in our search box.
We also have individual profiles on each kind of vegetable crop which you might find helpful: https://extension.umd.edu/hgic/plants/beans