Believe it or not, primroses are actually a great foundation for a garden. Their early bloom time makes them a must for the Northeast, getting some color into the garden when winter is still hanging on. They are low-growing, so you'll want to plant them up front where you can see them, along walkways, on the edges of flowerbeds, and along rock walls and fences. Available in stunningly bright colors, such as rich purples and electric yellows, they will not disappoint.
Crocuses' early bloom makes them a mainstay in the Northeast. Grown from bulbs, they need to be planted in the fall, with ample fertilizer, to bloom well in the spring. Their color range is limited to white, yellow and purple, but that makes them no less welcome in March and April.
Tall and bushy, lupines make a perfect alternative to flowering shrubs in smaller gardens, and are a great bedding plant in larger gardens. They come in a wide range of colors, from yellow to pink, in addition to purple, the most common color found in the wild. They do well in poor-quality soil, making them an even more attractive option for Northeast gardeners.
A relative of daisies, echinacea is a medicinal plant that also produces stunning, bold pink flowers, in late summer-early fall, and can grow to be over 3 feet tall. Echinaceas do best in dry soil, and are in fact, quite able to withstand very dry weather, so they are ideal to grow in areas where outdoor water use is strictly regulated.
Also from the daisy family, asters bloom a bit later than echinaceas in the fall---often hanging on even after light frost. They are found in shades of purple, with a bright electric purple being the most commonly available in garden centers. Pale lavender asters grow in the wild throughout the Northeast.
A succulent that grows well into the end of the growing season, sedum extends the season for many Northeast gardeners. It can withstand light frost, especially in a sheltered location, and produces small flowers, generally red or yellow. Its foliage is also attractive.