Black walnut trees produce a chemical called juglone that creates a toxic environment for most plants, trees and vegetables. As the walnut tree grows, the toxic planting zone extends; Ohio State University notes that mature trees have a toxic zone of 50 to 80 feet from the tree's trunk. While planting under a black walnut can be challenging, some annual and perennial plants thrive in those conditions.
A climbing vine that can grow up to 50 feet, Virginia creeper has red leaves that change to green when grown. The leaves come in clusters of five and are ovoid in shape. This vine can either climb up tree trunks or fences or can grow along the ground as a ground cover. Virginia creeper shoots out tiny green flowers in the late summer, then develops blue berries that attract birds and small animals.
Rose of Sharon
A shrub capable of growing up to 15 feet in height and width, Rose of Sharon flowers in the late spring. Also known as shrub althea, Rose of Sharon has jagged-edged green leaves. Its blossoms may be white, pink, purple or red and closely resemble the hibiscus flower; shrubs can have either single or double blossoms. Hummingbirds and bees enjoy the flowers.
Zinnia comes in an array of colors, including yellow, red, orange and purple. The flowers resemble tiny pompoms.Since zinnia are annual flowers, they need to be planted under the black walnut tree each year either via seed or by transplant. Once established, zinnia bloom all summer long. The flowers grow up to three feet tall and can spread up to two feet wide.
Also known as pot marigold, calendula produces bright orange flowers that have culinary and medicinal interest, according to University of Maryland Medical Center. Calendula petals can be added to soups and stews for color or mixed with vinegar to create a dye. The flower promotes healing from burns and wounds and can help relieve stomach cramps or ulcers, notes the University of Maryland Medical Center. Calendula grows easily from seed in either the sun or partial shade. This annual grows up to 12 inches high.