Dear Barbara, Growing season in N.E. is short, but a plant you can start from seed, easily, inside, before the ground thaws is the Morning Glory. You can also grow Evening Glories {no joke!}. They are all from the Ipomoea family. Those that open in the evening are pure white; a lovely contrast to the color of the Morning Glory. They are all from the Ipomoea family & a wonderful way to attract the birds and bees, particularly hummingbirds. Hummingbirds feed from dawn to dusk, but you might be surprised if some evening you're watering your Ipomoeas and get buzzed by some flyby; it'll almost certainly be a Sphincter Moth since the go home to roost.
Your pergola will be lovely if only for a summer.
