Susan Mahr, UW Horticulture
Item number: XHT1171
What is globe amaranth? Globe amaranth (Gomphrena globosa) is a tropical annual native to Central America from Guatemala to Panama. Its relative, G. haageana, is a tender perennial native to Texas, New Mexico, and northeastern Mexico. Globe amaranth grows one to two feet tall and approximately one foot wide with stiff, erect, branched stems bearing opposite leaves. The leaves are long and slender, and wooly-white when young, losing their white color as they age. Plants produce persistent, 1½ to two inch long, clover-like blossoms on upright spikes from summer through frost. Individual flowers are inconspicuous, but the stiff, papery bracts that form the bulk of the flowering structure are colorful and showy. Various cultivars come in shades of pink, purple, and white. Selections of G. globosa and hybrids with G. haageana have flowers in shades of red and orange.
There are many different cultivars of globe amaranth.
• ‘Bicolor Rose’ has pink and white blooms.
• ‘Buddy Purple’ is short (eight to 12 inches tall) and has intensely purple flowers.
• ‘Gnome Series’ has flowers in pink, purple and white, and grows only six inches tall.
• ‘QIS Series’ has flowers in white, purple, lilac, carmine, rose and red that are especially good as cut flowers;
• ‘Strawberry Fields’ (a G. haageana type) produces large, brilliant red flowers on 20 inch tall plants.
Where do I get globe amaranth plants? Globe amaranth can be purchased as a transplant, but is also easily grown from seed. Sow seeds indoors six to eight weeks before the expected last frost in the spring. Soak seeds for one or two days before planting to speed germination. Globe amaranth can also sometimes self-seed. Thus, once you grow globe amaranth in your garden, you may continue to see new seedlings appear each spring. Keep in mind however, that the flower color of these seedlings may be different than that of the parent plants.
How do I grow globe amaranth? Globe amaranth can be planted in the garden after all danger of frost has passed, but keep in mind that it will not thrive until warm weather arrives. It does best in full sun and prefers moist soil, but tolerates dry conditions once established. If plants are started indoors from seed, seedlings should be hardened off prior to transplanting. Space plants approximately 12 to 18 inches apart in the garden. Because the hairy foliage of globe amaranth easily collects soil, mulch around the plants for a cleaner appearance. Pinch out the first blossoms as they form to encourage bushier plants with more flowers. Regular cutting will also stimulate bushier plants and additional flowering. If growing the plants for cut flower production, place the plants six to eight inches apart to force longer stems. Taller plants should be staked as needed. Globe amaranth generally does not have many pest problems. However, under certain environmental conditions, it can be susceptible to powdery mildew (see University of Wisconsin Garden Facts XHT1005), gray mold (see University of Wisconsin Garden Facts XHT1122), and fungal leaf spots. Globe amaranth is not a preferred food of deer, but the plant’s flowers are very attractive to butterflies.
How do I use globe amaranth most effectively in my garden? Globe amaranth combines well with many other annuals in informal plantings. They are typically planted at the front of a border. Purple cultivars contrast nicely with yellow flowers like lantana (Lantana spp. – see University of Wisconsin Garden Facts XHT1165), blackfoot (Melampodium spp.) and shorter marigolds (Tagetes spp.). Pink or rose cultivars are set off by dark-leaved plants such as burgundy-leafed coleus (Coleus spp.) or ‘Blackie’ sweet potato vine (Ipomoea batatas ‘Blackie’). Try alternating rose-colored globe amaranth and ‘Victoria Blue’ annual salvia (Salvia farinacea ‘Victoria Blue’) behind white alyssum (Alyssum spp.) or cupflower (Nierembergia spp. – see University of Wisconsin Garden Facts XHT1179). Globe amaranth can be impressive massed in beds, but it also adapts well to container culture.
Globe amaranth works well as a fresh cut flower. This plant also works well as a dried flower because, if harvested properly, the flowers retain their shape and color. For best effect, harvest the blooms when they are completely open, but do not wait too long thereafter or the flowers may fall apart after they have dried. Hang the cut flowers upside down in bunches to dry. Flowers can be used on the stems or removed for craft projects. They often also are used in dried arrangements or for potpourri.