Gomphrena

Globe amaranth (Gomphrena globosa) is a tropical flowering summer annual native to Central and South America. It forms a dense, upright plant with round, clover-like flower heads in shades of pink, purple, or white. Plants usually reach 1 to 2 feet (30 to 61 cm) tall and 6 inches to 1 foot (15 to 30 cm) wide. The papery bracts keep their color well, so the flower heads can be dried for arrangements. The blooms draw bees, butterflies, and other pollinators.

Lifecycle. Most sources describe it as a summer annual, and it is tender to frost. In warmer zones it can also live as a perennial.

Sowing. Start seeds indoors about 6 to 8 weeks before the last frost. Seeds may also be sown directly outdoors, although direct seeding is not recommended by one grower-focused seed source. Sow the seed in flats or small containers and cover it lightly with about ⅛ inch (3 mm) of growing mix.

Temperature. Keep the seeds at a steady 70 to 75°F (21 to 24 °C) to germinate well. Another source gives 68 to 75°F (20 to 24 °C) for the ‘Fireworks’ cultivar, and a different source suggests 15 to 18°C (59 to 64°F) in early spring.

Germination. Seedlings usually emerge in about 2 to 3 weeks. The germination rate can be low, so sow generously.

Transplanting. Buying transplants is the easiest way to start, since most nurseries sell them in cell packs. If you start your own seedlings, harden them off after the danger of frost has passed and move them out into full sun. Plant out after the last frost in full sun.

Watering. Once established, the plant is drought-tolerant, but it does best with regular watering during the growing season. Water only when conditions are very dry if you prefer a low-water approach.

Light and soil. Give it full sun, and it can tolerate some partial shade. It grows best in moist, well-drained, fertile soil.

Deadheading. The ‘Fireworks’ cultivar does not need deadheading.

Few insect or disease problems are expected, but some cultivars may get gray mold, root rot, stem rot, powdery mildew, or leaf spots. Drought-stressed plants can develop mildew, so regular irrigation during dry spells helps prevent it.

For dried flowers, cut the stems when the flowers are fully open and the color is bright. Cutting them too late can make the flowers fall apart after drying.