Certified GKH Gardening Expert
Being a tree, they will need much less attention than a plant. If this is outside, you should only ever have to water if it remains dry for more than two weeks. Rainfall will be more than enough, as overwatering will cause infection.
If this is in container, and indoors, then you will water only once the top 3 or 4 inches of soil are completely dry.
This article will help you with the care of the tree: https://www.gardeningknowhow.com/ornamental/trees/ornamental-pear/bradford-pear-tree.htm