Is it a good garden plant?

It is usually considered a weed because it competes aggressively with crops for nutrients.

Yes, the leaves are edible when cooked, similar to spinach.

Plant guide

Redroot pigweed.

Amaranthus retroflexus

Pronounced am-uh-RAN-thus ret-roh-FLEX-us

Also known as American pigweed, Common Amaranth, Common Tumble Weed

Redroot Amaranth — Photo by Zihao Wang (CC BY) via iNaturalist

This hardy annual is often considered a weed, but it has a fascinating history as a food source. It grows quickly and produces massive amounts of tiny, dark seeds. You will find it popping up in disturbed soil across many regions.

At a glance

Care level: Easy
Plant type: Annual
Light: Full sun
Indoor light: Direct sun
Water: Every 3 to 7 days
Mature size: 1 to 6.5 feet
Growth rate: Fast
Hardiness: USDA 2 to 11
Bloom time: Mid summer to early autumn

Care

Just give it plenty of sun and keep the soil from drying out completely. Watch for rapid growth during the heat of summer. It is very adaptable but prefers loose, fertile soil.

Watering: Keep the soil consistently moist but not waterlogged for the best growth.
Feeding: A balanced liquid fertilizer helps if the soil is poor.
Pruning: Remove flower spikes early if you want to prevent it from spreading seeds everywhere.
Repotting: As an annual, this plant completes its life cycle in one season and does not require repotting.
Soil: Loamy, well-draining soil
Soil pH: 6.0 to 7.5
Temperature: 10 to 35°C
Humidity: 30 to 70%
Drought tolerance: High
Lifespan: Annual, typically 1 growing season
Deer and rabbits: Moderate

Safety

People: The plant is generally safe to eat when cooked, but raw consumption in large quantities is discouraged due to nitrate and oxalate content.
Pets: This plant can build up nitrates and oxalates and is a known cause of poisoning in livestock such as pigs and cattle. A small nibble is unlikely to harm cats or dogs, but do not let pets eat large amounts.
Children: The tiny seeds are a potential choking hazard if ingested in large amounts, though the plant is not inherently poisonous.
Contact allergens: The stems can be slightly prickly or rough, which may cause minor skin irritation in sensitive individuals.
Airborne allergens: The abundant pollen produced by the flowers can trigger seasonal allergies in susceptible people.
Edibility: Leaves contain oxalates and should be boiled in water before consumption to reduce potential kidney irritation.

How to identify it

Stiff, upright, hairy stems
Oval shaped, alternate leaves
Dense, bristly flower spikes
Deep red or pink taproot
Tiny, shiny black seeds

Height: 0.3 to 2m
Spread: 0.2 to 0.6m
Leaves: green, deciduous
Flowers: green, 0.1 to 0.3cm
Fruit: black, Autumn

Problems to watch for

Leaf spot · Fungal infections can cause dark spots on foliage during periods of high humidity.

By symptom

Plant problems by symptom

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Growing it

Propagation: seed
When to plant: spring
Overwintering: The plant dies completely after the first hard frost, so simply clear the debris to prevent seed dispersal.
In containers: It grows poorly in containers due to its deep taproot and aggressive growth habit.

Direct sowing

1. Scatter seeds on loose soil in spring.
2. Lightly cover with soil.
3. Keep moist until germination.

It is best to keep this plant away from your main vegetable beds to prevent it from outcompeting your crops.

Grows well with

Corn · They share similar light requirements but often compete for space.

Keep away from

Tomato · It is a vigorous competitor that can stunt tomato growth by hogging soil nutrients.

Similar species

Smooth pigweed · It looks very similar but has smoother stems and slightly different flower structures.

Science

Family: Amaranthaceae
Genus: Amaranthus
Order: Caryophyllales
Class: Magnoliopsida
Native range: Central and North America
Conservation: This is a widespread weed and is not of conservation concern.

It thrives in disturbed soils and open areas where it can quickly outcompete other seedlings for sunlight.

Value to wildlife: pollen source, seed source for birds
Pollinators: bees, butterflies, beetles
Uses: foraging, green manure, soil stabilizer

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 6/9
Light: 8/9
Temperature: 7/9
Moisture: 5/9
Nutrients: 7/9

Taxonomy resolved against GBIF.

Questions people ask

Is it a good garden plant?: It is usually considered a weed because it competes aggressively with crops for nutrients.
Can I eat it?: Yes, the leaves are edible when cooked, similar to spinach.

Where the name comes from

The name Amaranthus comes from the Greek word meaning unfading, while retroflexus refers to the bent back appearance of the flower spikes.

Good to know

It is commonly known as redroot pigweed because of its reddish taproot.
The plant is a C4 photosynthesizer, allowing it to grow rapidly in hot, sunny conditions.
It is often found in vegetable gardens and disturbed fields.

Also in

Plants toxic to cats and dogs

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This guide was generated with AI on October 19, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.