Fall is for Planting!
As noted in the New York Times article by Margaret Roach:

Next year, there will be no spring planting at Brooklyn Bridge Park, except for some tree species that resent fall root disturbance.

“When we do plant in spring, and then summer arrives, it can be such an extreme environment — hot, dry and windy, too,” she said, and those are hard conditions for plants trying to root in. With a fall planting schedule, the winter that follows is easier on them.

Spring planting is tough on gardeners, too, who have to keep after new installations with regular watering, or risk losing them. Fall planting gives plants time to establish themselves, and some are fully settled by the following summer, so watering isn’t needed then. Peak planting time at the park is from late September through early October or so, with grasses going in earlier in September, for extra rooting time.

“If you time it right,” Ms. McMackin said, “sometimes you only have to do a month of watering, and then walk away from the plant.”