Ornamental · Amaranthaceae
Globe Amaranth
Gomphrena globosa
Give globe amaranth full sun and warm, well drained ground, and it lifts papery clover-like flowers from summer until frost.
Full sun
Every 5–10 days
70–75°F · 21–24°C
84–112 days
Overview
The signature of globe amaranth is its round, papery flowerheads, each a tight cluster of stiff, dry bracts packed into a globe the size of a clover bloom. The bracts are what hold the color, so the heads stay bright for months rather than dropping soft petals. It grows as a tender annual across a wide range of climates and shrugs off heat and dry spells better than most summer flowers.
The globes open in pink, purple, white, and red, each one perched at the tip of a slender, wiry stem that rises from a low, tidy mound of green leaves. Cut and hung to dry, the heads keep their firm round shape and their color for a year or more, which is why they fill so many everlasting bouquets. In the garden the small blooms draw butterflies while deer pass them by.
Up close the plant reads as neat and unfussy: a compact clump of foliage sending up those thin stems, each tipped with a crisp, papery button. It suits a beginner, needing little once settled and flowering on as long as the spent heads are picked. Give it sun and room for air to move, and the worst problems stay away.
Care
The short version: full sun, average well drained soil, and steady moisture while young, then ease off since it handles heat and drought once established. Feed every couple of weeks through the season and deadhead to keep the papery heads coming.
Light
Globe amaranth wants full sun, at least 6 hours of direct light a day. In part shade the wiry stems stretch, lean over, and carry far fewer of the papery heads. The more sun it takes in, the thicker the crop of flowers.
Water
Keep the soil evenly moist while the young plants are getting established. After that, ease right off, because it handles heat and dry spells well and resents wet feet. Let the top half of the soil dry before you water again, since soggy ground invites disease.
Soil
Average, well drained soil is all it asks for. A pH between 6.0 and 7.0 suits it, and it tolerates poor ground better than most. What it will not forgive is heavy, soggy soil that stays wet.
Temperature
Warmth suits this plant down to the ground, with growth strongest at 70°F to 75°F (21°C to 24°C). Hot summers leave the stiff stems and papery heads unbothered, but a single frost finishes it, so set it outside only once cold weather is done.
Humidity
Ordinary outdoor humidity is fine, so there is no number to chase. Air movement matters far more, since still, damp air around crowded plants is what brings on mildew and mold.
Feeding
Feed at planting with a water-soluble fertilizer, then keep it going every couple of weeks through the growing season. Regular light feeding supports the long run of papery blooms.
Pruning
Deadhead or cut the spent flowerheads to keep new ones coming all season. Pinch young plants back early too, which draws out more side branches and a fuller, bushier clump.
Size & spacing
A mature clump stands 12 to 24 inches (30 to 61 cm) high and fills out to 6 to 12 inches (15 to 30 cm) across. Give each plant a gap of about 8 inches, enough room for air to slip between the wiry stems and keep the foliage dry.
When to plant
Globe amaranth is a warm season annual with no tolerance for frost. Start the seeds indoors in late winter or sow them outside once the soil has warmed, and the plants flower from early summer until the first frost.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6 to 8 weeks before last frost; soak seed overnight and keep at 70 to 75°F for germination in 2 to 3 weeks
- Plant: After all danger of frost has passed and soil has warmed, spaced about 8 inches apart
- Harvest: Blooms from early summer through fall until frost
Hardiness
USDA hardiness zones: 2–11
Temperature: down to -46°C
Troubleshooting
Most trouble with globe amaranth shows first on the leaves, brought on by damp, crowded conditions or too little sun. Read the early marks on the foliage and you can usually turn things around with better spacing and steadier watering. Match what you see below, then act before it spreads.
Soft gray fuzz or dark blotches marking the leaves
A wet, cool spell brings on gray mold (Botrytis) and scattered fungal leaf spots that stain the green with fuzz and dark marks. Strip away the marked foliage as it shows, and water at the base so the leaves are never left wet. Set the plants wider apart to let air slip through and dry the surfaces.
Fix:
- Remove affected plant parts
- Avoid overhead watering and wetting foliage
- Increase spacing and air movement
Only a scattering of seedlings breaking the surface
Globe amaranth seed is slow to rouse and low-germinating by nature, and cold soil keeps it dormant longer. Soak the seed overnight and hold the soil at 70°F to 75°F (21°C to 24°C) to draw the sprouts out. Sow a little extra to fill the bare patches, and leave direct sowing until the ground has warmed.
Fix:
- Soak seed in water overnight before planting
- Maintain 70 to 75°F soil for germination
- Sow extra seed to compensate for low germination
A chalky white dusting over the leaf and stem surfaces
That pale, floury film is powdery mildew, a fungus that takes hold when the plant runs dry or lingers through cool, damp air. Ease the plants apart, thin the crowded growth, and water on a steady schedule so the foliage dries and the air keeps moving. Pick off the leaves that wear the thickest coating and throw them out.
Fix:
- Improve air circulation by spacing and thinning
- Water consistently to avoid drought stress
- Remove and discard severely affected foliage
Pale, elongated stems bending under only a few blooms
Stems that stretch thin and lean over with only a handful of flowerheads are short on sunlight. Give the plant a spot with at least 6 hours of direct light a day and the growth tightens up. Pinch the young plants back early to draw out more side shoots and a denser cap of flowers.
Fix:
- Relocate or plant in full sun
- Pinch young plants to encourage branching
Toxicity
Those stiff, papery flowerheads carry no poison anywhere in the plant. The ASPCA classes globe amaranth as non-toxic for cats, for dogs, and for horses, and neither leaf nor bloom poses any threat to people or other animals. A pet that wolfs down a big helping of any greenery might feel queasy for a short spell, and that is the extent of it.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
The ASPCA lists globe amaranth as non-toxic to cats. A cat that bites into the dry, papery flowerheads comes to no harm, though a large mouthful of any plant may bring on a little drooling or a brief stomach upset.
Dogs None
It is safe for dogs. The wiry stems and stiff flowerheads carry no poison, and the worst a dog gets from overeating is a mild, passing stomach upset.
Horses None
Globe amaranth is non-toxic to horses, and a mouthful pulled while grazing poses no real risk.
Rabbits Safe
Rabbits can strip the soft green foliage without harm. No toxin sits in the leaves, so the plant is safe if one reaches the bed.
Livestock Safe
Cattle, goats, and sheep can graze around it safely, since the stems and leaves hold nothing toxic to farm animals.
Birds Safe
Birds come to no harm near it, and many pick the seed from the dried heads, leaving the plant safe for backyard and pet birds alike.
People Safe
Globe amaranth is safe for people, and the dried flowers are even steeped into a herbal tea in some places. There is no need to keep children away from it.
Varieties
Globe amaranth ranges from tall cutting types to tidy dwarfs for edging, and the heads differ in color and size across them. These are the ones you will meet most often.
Strawberry Fields
A taller form at 18 to 28 inches, it holds bright red bracts pricked with tiny yellow true flowers.
Las Vegas series
Compact at 16 to 20 inches, its heads open in pink, purple, and white for an easy blend of colors in one bed.
Buddy series
A dwarf standing just 6 to 8 inches, it fits edging and tight spaces where taller forms would crowd in.
Fireworks
Its glittering pink bracts finish in bright yellow tips, and it keeps flowering longer than most other globe amaranths.
How to propagate
Seed is the only route to a new globe amaranth, and the sole catch is waiting on the slow, reluctant sprouts to push through.
SeedEasy
Start indoors 6 to 8 weeks before last frost, or direct sow after frost and once soil is warm · Germinates in 2 to 3 weeks; blooms about 12 to 16 weeks after sowing
Globe amaranth rises from seed, sown indoors 6 to 8 weeks before your last frost or set into warm ground once the cold has gone. An overnight soak and a warm bed at 70°F to 75°F (21°C to 24°C) coax the small seed into sprouting within 2 to 3 weeks. Harden the seedlings before they meet full sun, and the first papery heads unfurl roughly 12 to 16 weeks after sowing.
Myths
Globe amaranth won't flourish unless you water it often.
Once its roots take hold, this plant carries heat and dry weather without wilting, so steady drenching is not the answer. A heavy, unbroken schedule works against it, since wet soil and damp leaves are just what mildew and rot settle into. Water it well while young, then ease off and let the top of the soil dry between drinks.
Globe amaranth is toxic to pets.
The ASPCA lists it as non-toxic to dogs, cats, and horses. A pet that swallows a large mouthful might feel briefly off, but there is no genuine poison in the leaves or flowers.