Between the influx of people, cars, homes and businesses, it comes as no surprise that Boston is running out of space on the ground. It’s also gaining green space upward, which could be part of the key to tackling heat and climate challenges. Dozens of feet above our heads sits a string of urban oases. Vertical vegetation spots are growing in popularity. And while they’re not necessarily new, the tactic is newer to Boston. Stream NBC10 Boston news for free, 24/7, wherever you are.