The best time for planting is in spring or fall. Plants need a little more attention in the summer. Follow planting instructions and anything you plant should be a success.
Trees and Shrubs – the best time to plant trees or shrubs is when they enter dormancy, when they drop their leaves, or in the spring. How to Plant a Tree
Evergreens – avoid planting when it is too hot or dry.
Perennials– spring is prime perennial planting season but summer and fall will work, the plants will just need a little extra TLC.
Intense heat is a major enemy to newly planted plants. Give them all a good watering when planting to provide enough moisture to help get them properly established. You may need to use water bags or an irrigation system to help them along.