How to Grow Amaranthus retroflexus Plants in your Garden

Better known as Pigweed, the common Amaranth (Amaranthus Retroflexus) reaches an height of about 3 feet (0.9 m).

other common names for this plant include Redroot Amaranth or Wild Beet

Although many people conider it to be a weed, this is perhaps one of the best Amaranths to grow if you wish to harvest the seeds for grain.

In fact, Indian chefs from Kerala often make thoran, one of their signature dishes, with this hardy little plant.

Pigweed, somewhat notoriously, also forms tumbleweeds in the wild.

If you're interested in growing a garden of these beautiful grain amaranths yourself, there are a few things worth noting before you start.

The leaves of Amaranthus retroflexus also have culinary use, and are often used as a replacement for spinach plants in Mexico – where it is native to.

Common amaranth
Amaranthus retroflexus photograph by Matt Lavin.

This annual amaranth grows well in USDA zones 3 to 11, and is rated at UK hardiness H4. This makes it hardy down to about -10°C (14°F). The plant is sensitive to very long cold conditions, so shouldn't be grown in extreme climes.

Primarily, these Amaranths are summer annuals and start to bloom in July. Blooming occurs from the middle of summer through to early autumn. The flowers are inconspicuous and green in colour. They form dense panicles, which can reach up to eight inches (20 cm) in length.

Plants carry either male or female flowers (monoecious), and are wind pollinated.

Seeds (1/10th inch / 2 mm) begin to ripen in the late summer and early fall, starting around August and continuing to October.

Once blooming has finished seeds will set and ripen from late summer through to the middle of autumn (Seeds (1/10th inch / 2 mm).

Gardener's HQ Guide to Growing Common Amaranth

Pigweed is an outdoor plant that can't grow without plenty of sunlight, so make sure it is located in a sunny area, well outside the reach of any heavy shade (some light shade is usually fine).

They're suitable for a wide range of soil types and can endure a lack of water, but do best when they have a steady supply. Plants prefer a moist soil, as this promotes growth. Water regularly

Seeds can be sown in their final location towards the end of spring.

Or start Amaranthus Retroflexus in the greenhouse and transplant out following the last frost of spring

Does not like wind, so grow in a sheltered location.

Can be grown in pretty much any soil types and acidities. For best results grow in a rich soil.

Be sure to dig your trenches deep to give plant roots plenty of room to clump and grow.

If you're at all intending to consume this plant in any way, whether medicinal or food, you should not use inorganic fertilizers as nitrates have a tendency to congregate in the leaves.

The reasoning for not feeding Amaranthus Retroflexus inorganic fertilizers is that the plants have very effective photosynthesis (C4 pathway). This can lead to an abundance of unwanted chemicals being available for the leaves and seed. This can result in the plant becoming toxic to humans.

Amaranthus retroflexus Growing and Care Guide

  • Scientific Name: Amaranthus retroflexus
  • Common Name: Common amaranth, Pigweed, Wild beet, Redroot amaranth.
  • Growing Zone: USA: 3 to 11; UK Hardiness H4.
  • Life Cycle / Plant Type: Annual.

Plant Details

  • Plant Height (Inches): 12 to 36 (30 to 90 cm).
  • Plant Spread (Inches):
  • Time of Bloom: Late spring to early autumn.
  • Flower Details: Small, natively green. Red, purple, pink, orange flowered cultivars available.
  • Leaf Foliage: Green. Ovate leaves.
  • Fruit: Eddible seed in autumn. Glossy, dark.
  • Growth Form: Clumping

Ideal Growing Conditions

  • Best Light Conditions: Partially shady to full sun
  • Rate of Growth: Just under a cm per week when at its greatest (early summer).
  • Suitable Soil Types: Ordinary soil, not too rich, PH 6 to 7 for best results, but will tolerate quite high alkaline and acid soils.
  • Soil Moisture: Good Drainage, Moist

Caring Conditions

  • Level of Maintenance: low
  • Propagation: Seeds: late spring. Can also be grown from cuttings.
  • Pests:
  • Diseases:

Further Information

  • Can Attract:
  • Tolerant of: Fire
  • Best Garden Use: Cover, Wild flower garden; often considered a weed.
  • Family: Amaranthaceae
  • Closely Related Species: Amaranth, French Spinach.

  • Miscellaneous: Attractive to birds. Do not grow in soils that are rich in nitrogens as the plant readily takes up this element; this can lead to toxicity.
  • Genus Detail: Amaranthus
  • Further Reading and References: Here and Here

Amaranthus retroflexus makes a good companion plant for many types of vegetables. Some of the ones recommended by the gardenersHQ website include Eggplants, Tomatoes, Peppers and Maize.

I hope that you enjoyed this guide on how to grow Amaranthus retroflexus. You may also enjoy the following Amaranthaceae growing guides: How to grow Kochia and Gomphrena plants.