About a week ago I planted one midnight magic crape myrtle and one lunar magic crape myrtle in my backyard. They get full sunlight, I’ve watered twice but the leaves are starting to wilt, they look like they are dying. Is there anything specific I can do to prevent them from dying

You are right, they look stressed. At the nursery, they were probably getting watered daily. Now, they are in the landscape and miss being pampered. I would mulch around the base to help conserve water and also keep the roots cool. Then, water deeply almost every other day. Gradually, stretch it out so you are watering less frequently. If they drop their leaves from the stress, don’t panic. They might grow new ones this year. Take a look at the First Editions planting and care guide for additional tips.