Q.Planting in the summer
I was planning to install an entire landscape consisting of mostly small container evergreens (Boxwood, Holly, etc…) a few larger container crepe myrtles, and some perennial flowers, this spring. Due to extenuating circumstances the install was delayed until now (end of June). Is it too late to plant now due the fact that we often get temps in the high 80s low 90s? (Central NJ) I would hate to have to push this off until autumn. Thanks.
Yes, ideally spring and fall are best times to plant out trees, shrubs and landscaping projects.
You certainly can complete your project now, but need to take extra care in maintaining watering to keep the plants alive, happy and through the heat.
Try to avoid overly hot days if possible. Plant in mornings or evenings, at the coolest part of the days.
Apply 3 to 4 inches of hardwood mulch to help with moisture control and to keep the roots cool. Keep the mulch from touching the bark of the shrubs and trees.
https://www.gardeningknowhow.com/ornamental/trees/tgen/watering-newly-planted-tree.htm