Hi! I am planning to grow vegetables on an extensive green roof, but can't find any summer season vegetables that are suitable.. The soil depth is about 2.5 inches, or 6 cm. I am growing them during the summer, so they have to be: - shallow rooted vegetables - heat tolerant - full exposure to sunlight - not too tall (due to wind at rooftop levels) - grow within 4-6 weeks Any ideas? Thanks!