Palmer Pigweed

Biological Name:

Amaranthus palmeri spp. palmeri (Palmer-Pigweed)

Natural Habitat:

Palmer-Pigweed: The natural habitat of Palmer-Pigweed is in open, disturbed areas such as fields, roadsides, and waste places, in the eastern and central regions of North America.


Palmer pigweed is a type of flowering plant that is commonly found in fields and other grassy areas. It is a member of the Amaranthaceae family which also includes plants such as amaranth and quinoa. Palmer pigweed is an annual or perennial plant that produces small green or red flowers and clusters of seeds. The plant is often used as a cover crop to improve soil health and suppress weeds. It is also known for its ability to tolerate a wide range of growing conditions including wet or dry soils. In some areas Palmer pigweed is considered a weed because of its ability to invade cultivated areas and cause allergies and other health problems.

Frequently Asked Questions (FAQs)

Q: Is Palmer amaranth the same as pigweed?
A: Palmer amaranth (Amaranthus palmeri) is a summer annual broadleaf weed that is native to the southwestern US and Mexico. It is also known as Palmer pigweed.

Q: Is Palmer amaranth toxic?
A: Palmer amaranth can also be toxic to livestock animals due to the presence of nitrates in the leaves. What can you do? As landowners and farmers, be proactive in identifying palmer amaranth on your property to prevent establishment.

Q: Why is Palmer amaranth a problem?
A: Palmer amaranth competes aggressively with crops. It has a fast growth rate of 2- 3 inches per day and commonly reaches heights of 6- 8 feet, greatly inhibiting crop growth. Yield losses have been up to 91% in corn and 79% in soybean.

Q: Is amaranth toxic to humans?
A: Avoid eating too much amaranth from agricultural fields. The leaves (like those of spinach, sorrel and many other greens) also contain oxalic acid, which can be poisonous to livestock or to humans with kidney issues of eaten in large amounts.

Q: What part of pigweed is poisonous?
A: Pigweed (Amaranthus retroflexus) is a common annual weed found throughout the United States. The weed can grow three to four feet; the flowers are green and prickly and the plant has oval shaped leaves. The pigweed’s leaves, roots and stems are toxic.

Q: Is Palmer amaranth invasive?
A: Palmer amaranth is an invasive weed species we have been hearing a lot about in agriculture over the last 10 years, and it continues to be a threat after its first documented appearance in Illinois in 2012. Native to southwestern US states, palmer amaranth has made its way to 39 of the states.

Q: Why is pigweed so difficult to control?
A: The researchers have determined a specific genetic feature, the extrachromosomal circular DNA (eccDNA) replicon, gives pigweed, or glyphosate resistant palmer amaranth, its resistance to glyphosate and makes this weed difficult to control.

Q: Is Palmer pigweed edible?
A: The leaves, stems and seeds of Palmer amaranth, like those of other amaranths, are edible and highly nutritious. Palmer amaranth was once widely cultivated and eaten by Native Americans across North America, both for its abundant seeds and as a cooked or dried green vegetable.

Q: Is pigweed poisonous to humans?
A: Yes, the weeds in the garden we call pigweed, including prostrate pigweed, from the amaranth family, are edible. Every part of the plant can be eaten, but the young leaves and growing tips on older plants are the tastiest and most tender. The seeds are nutritious, edible, and are not difficult to harvest.

Q: How do I get rid of Palmer amaranth?
A: Glyphosate – Glyphosate can be used as a spot treatment to control Palmer amaranth. Glyphosate will kill or injury any plants it contacts, thus creating open areas that other weeds will invade.

Q: Should I remove pigweed?
A: If you spot pigweed plants that have yet to produce mature seeds, pull them or cut them off just below the soil line. Plants with mature seeds should be bagged before being removed and destroyed. Either burn the plants or bury them under at least a foot of compost.

Q: What kills Palmer pigweed?
A: Populations of Palmer amaranth have been documented with resistance to one or more of the following classes: Dinitroanilines, triazines, ALS (acetolactate synthase) inhibitors, glyphosate and HPPD (4-hydroxyphenylpyruvate dioxygenase) inhibitor herbicide.

Q: Is amaranth an invasive plant?
A: Amaranthus palmeri is an annual herbaceous plant that is spreading rapidly beyond its native range in North America. It is considered the most invasive species of the dioecious amaranths and is ranked as one of the most troublesome weeds of various crops in the United States.

Q: What is pigweed good for?
A: The leaves of pigweed are also incredibly nutritious. They’re high in vitamins A and C and folate, as well as calcium. In Jamaica, pigweed is known as callaloo and is a culinary staple.

Q: Is pigweed toxic?
A: Pigs allowed access to pastures or lots containing pigweed (Amaranthus retroflexus) may be poisoned. Most poisonings occur in the late summer or fall. Signs appear within five to ten days after exposure and include trembling, weakness, incoordination, knuckling, and almost complete rear leg paralysis.

Q: Why do they call it pigweed?
A: Their common name, pigweed, may have comes from its use as fodder for pigs. Pigweed plants are commonly considered to be weeds by farmers and gardeners because they thrive in disturbed soils.

Q: Should you pull pigweed?
A: If pigweeds are in the advanced reproductive stage and might drop viable seed when handled, carefully bagging plants is even more important, Farr and others say. Guy Collins, cotton Extension associate professor at North Carolina State University, also advocates hand pulling.

Q: Is pigweed toxic to dogs?
A: Amaranth greens, sometimes called pigweed, are toxic for dogs because of oxalates and nitrates that are present in the vegetable. If consumed, oxalates and nitrates can cause kidney failure in dogs.

About the author

Samuel is a gardening professional and enthusiast who has spent over 20 years advising homeowners and farm owners on weed identification, prevention and removal. He has an undergraduate degree in plant and soil science from Michigan State University.