The Globe Amaranth (Gomphrena globosa) is a popular and cheerful addition to many gardens. This flowering plant is celebrated for its distinctive, clover-like blooms that sit atop slender stems. The flowers are notable for their papery texture, which allows them to retain their color and shape long after being harvested. This characteristic has earned the Globe Amaranth a reputation as an “everlasting flower,” making it valued for use in dried floral arrangements and crafts.
Understanding the Life Cycle: Annual vs. Tender Perennial
The classification of Globe Amaranth depends entirely on the climate in which it is grown, leading to its dual designation as both an annual and a tender perennial. Botanically, Gomphrena globosa is a warm-weather perennial, meaning it is capable of living for multiple seasons. It originates from the tropical and sub-tropical regions of Central America. This perennial habit is maintained only in frost-free environments, specifically in USDA Hardiness Zones 9 through 11. In these mild regions, the plant can be treated as a short-lived perennial, often dying back partially in the cooler months and regrowing when temperatures rise. In temperate climates that experience freezing winter temperatures, the plant cannot survive the cold. Gardeners cultivate the Globe Amaranth as an annual, completing its entire life cycle within a single growing season before dying off with the first hard frost.
Essential Growing Requirements
Globe Amaranth thrives in full sun, requiring a minimum of six hours of direct sunlight each day for optimal growth and flowering. Planting the specimen in a partially shaded location results in a reduction of flower production and a weak, leggy growth habit. The plant is adaptable to various soil conditions but performs best in soil that provides excellent drainage.
The species is known for its tolerance to heat and dry conditions, making it an excellent choice for hot summer climates. While it is considered drought-tolerant once established, the plant will produce a greater abundance of blooms if given regular watering. Soil with average fertility is preferable, as excessive richness can lead to soft, weak stems and a decrease in the quantity of flowers produced.
Strategies for Propagation and Return
Gardeners outside of the warmest zones must ensure the return of Globe Amaranth each year, typically through seed or cultivation. The most common and reliable method is starting the plant from seed indoors six to eight weeks before the final expected frost date. The seeds germinate most effectively when given warmth, ideally maintaining a soil temperature between 70 and 78 degrees Fahrenheit.
To improve the rate of germination, the seeds can be soaked in room-temperature water overnight before being sown. Since the plant naturally produces and drops a large quantity of seeds, it can often self-seed in the garden, resulting in volunteer seedlings the following spring, especially in mild-winter locations. For more intentional planting, the dried flower heads can be collected at the end of the season to harvest the seeds for storage and planting the next year.
For those attempting to keep a specific cultivar alive through the winter, overwintering a potted plant indoors is an option, though it is often challenging. This process involves bringing the plant inside before the first frost and placing it in a bright, cool location. The plant often struggles to survive in the lower light and humidity conditions of a typical home environment. In its true perennial zones, the plant is simply cut back to the ground level after the blooming season concludes, allowing it to regenerate when the weather warms again.