According to the United States Department of Agriculture (USDA) Plant Hardiness Zone Map, Zone 4 covers a good chunk of the Northern United States. The growing season is shorter in this zone than in the southern tier. Short and sweet: Zone 4 gardeners know they need to make the most of their brief window of opportunity.
Zone 4 gardeners have a wide array of perennials to choose from. One of the first to bloom in the spring is the snowcap, or arabis, with its small white blossoms. For more colorful early blooming, plant purple and yellow crocuses, which grow to be about eight inches tall, and true-blue Siberian squill.
Siberian squill will spread all over the lawn if allowed to, creating a beautiful blue carpet that lasts about a week. Dianthus, also known as fire witch, blooms from spring through late fall if you deadhead, or remove the spent blossoms. The bright pink flowers smell like clove. Heliopsis, or false sunflower, also bloom for months. These plants grow three to four feet tall and have large yellow blossoms.
Autumn sedum add year-round interest to the garden. Their pink flower heads bloom in the fall but dry to a coppery-brown color that gives a little color to this zone's long winter.
With all the wonderful perennials available, you really don't need any annuals. But don't let that stop you, because there are some great flowers which are only available as annuals.
Must-have annuals for Zone 4 include the hardy marigold, which you can plant early and enjoy until the first frost; snapdragons, another hardy winner available in pink, purple, red, yellow, and white; and petunias.
Petunias, with their delicate flowers in purple, white, pink or red, might look fragile, but will bloom even after a light freeze. And don't forget the pansies. Pansies bloom early and late in the season, preferring the cooler weather this zone is known for.
Rely on bushes to give your garden color year-round, such as the hydrangea, the spirea and Japanese bayberry. Many types of hydrangeas do well in Zone 4. They produce large flowers in white, pink, or blue from spring through fall.
Spireas also perform well, growing to six feet tall unless pruned back; they have sweet-scented pink, white or red flowers. The Japanese barberry produces yellow flowers in the spring, leaves that turn orange or reddish- purple in the fall, and bright red berries lasting all winter.
Some consider the Japanese barberry to be an invasive plant, so discuss it with your local nursery workers.They are always a good source of information about which plants will perform best in your area.