Delay in planting trees
Watering when needed will be the most important aspect for maintaining a containerized dogwood through the summer. If the tree is root bound within the pot you might want to pot it into a larger pot with some added soil to help hold it over the summer. Another way to hold the plant is to "heel" the pot in which means to simply mound mulch or leaves around the pot to help hold in moisture. Also placing the tree in a location where it gets sun early in the day and not the late afternoon sun or heat will help with maintaining good health. Be sure to water only when the soil is dry - not bone dry of course to the point of wilt.. but when the top few inches are dry. Overwatering most likely wont be a concern but is possible.
Please feel free to call the office if you have further questions.