Q. When do crape myrtles emerge in NYC? In other words, is it still alive if it hasn't bloomed by May??
Crape myrtle (Lagerstroemia spp.) is the quintessential Southern flowering tree but, depending on the variety, it can be grown in Zones 6 - 7 (including New York City). This species does leaf out much later than most trees and shrubs but if you don’t see leaves by the end of May it would seem that your tree has sustained winter damage (or is suffering from some disease). Flowers should appear later in the summer, typically July to September in New York City.
We did have a few days of 0°F last winter and many crape myrtles were damaged. If you don’t see leaves in late spring then you can check the buds and branches to see if the plant is still alive. To do this remove buds and cut them in half. If the buds are brown on the outside and green on the inside then the tree has suffered cold damage during the last winter and may recover. If the bud is totally brown then the tree is possibly dead.
You can also scrape off some of the bark on some of the limbs and see if they are green underneath. If they are all brown then the tree is probably dead. If some branches are dead and others are alive then you should prune away the dead branches.
If you need to replace a dead tree be sure to pick a variety that is hardy in this area and plant it in a location sheltered from north winds.
Courtesy of NYBG Plant Information