Thorny Amaranth
Amaranthus spinosus
Last reviewed: August 2026
Toxicity unknown
Thorny Amaranth (Amaranthus spinosus) is not listed by the ASPCA Animal Poison Control Center (opens in new tab) or the other sources we check, so we have no verdict for it either way. Absence from those lists is not a clearance. If your pet shows symptoms after eating any plant, call the ASPCA at (888) 426-4435.
Light
full sun
Water
medium
Size
12"–48" H × 6"–24" W
Bloom
Jul, Aug, Sep
Pollinators
bees, beetles
Native alternatives to Thorny Amaranth
Thorny Amaranth is not native to the United States. These natives fill a similar role in a planting, matched on bloom season, bloom color and mature size.
Before you buy
Your city may pay you to plant this
Cities and water utilities offer rebates for replacing lawn with native and water-wise plants. We track 452 programs across 44 states, each with a link to the provider and the date we last checked it.
Find rebates in your areaThorny amaranth is a fast-growing annual wildflower with upright stems and small greenish flower spikes that bloom through summer and fall. This native plant has spiny stems and can self-seed readily in disturbed soils. It thrives in hot, sunny conditions with moderate water needs.
In an HOA neighborhood
Thorny Amaranth takes more care to keep looking intentional in a front yard. Maintenance level: high. Consider it for backyard or mid-zone beds rather than the street edge.
Works well in: backyard only.
- Sharp spines pose safety hazard
- Extremely weedy appearance
- Self-seeds aggressively
Wildlife value
The summer blooms attract bees and beetles for pollen and nectar. Seeds provide food for birds and small wildlife in fall.
Common questions
- How much sun does Thorny Amaranth need?
- Thorny Amaranth grows best in full sun conditions.
- When does Thorny Amaranth bloom?
- Thorny Amaranth blooms in July, August, and September.
- What pollinators does Thorny Amaranth attract?
- Thorny Amaranth draws bees and beetles.
- Is Thorny Amaranth HOA-friendly?
- Thorny Amaranth takes more care to look intentional in a front yard. Consider it for backyard or mid-zone beds rather than the street edge.
Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.
If something looks wrong
Common plant problems, and what to check first
These come up on almost any plant. Each guide lists the likely causes in the order they are worth ruling out, with one thing to check before you act on any of them, and links to the source it came from.
- It is dying right after planting
- Leaves turning yellow
- Wilting even though I watered it
- Brown crispy leaf tips
- Bugs on the plant
Ready to grow Thorny Amaranth? Add it to your garden in Pollinator Patch to track it and get season-by-season care guidance.
Planning a bed around it? Start a free plan with this plant
Not sure where to start? Take the 2-minute yard quiz