Pigweed (Amaranth): Identification, Control, & Types

What is Pigweed (Amaranth)?

Pigweed, or amaranth as it is also known, is a versatile plant that can be seen in many gardens. It is a common name for several species of weedy plants belonging to the Amaranthus genus, including redroot pigweed (Amaranthus Retroflexus), smooth pigweed (Amaranthus Hybridus), and Palmer amaranth (Amaranthus Palmeri).

This plant is native to the tropical Americas but is widespread as an introduced species on most continents in a great number of habitats. 

Amaranth is an annual, which means it has a one-year life cycle. It normally reaches a height of one to six feet, with erect stems and long, narrow leaves.

This plant is a prolific seed producer and is capable of producing hundreds of thousands of seeds per plant. Because these seeds can survive in the soil for several years, this plant can quickly come back even after it has been removed.

It is a cause for concern in gardening because this plant is very adaptable and can grow in a wide range of conditions and soil types. It is also resistant to many common herbicides, which makes it difficult to control.

Although pigweed can be considered a wild edible, it can also serve as a beneficial companion plant in the garden. Furthermore, its nutritional value is undeniable, as it contains various important vitamins, minerals, proteins, and essential fatty acids. Therefore, many farmers have started growing this plant for consumption.

Let’s know all the details about Pigweed in this article, including its types, benefits, etc.

Pigweed (Amaranth) At A Glance

Key information about pigweed (amaranth):

Scientific nameAmaranthus spp.
Common namePigweed
Plant typeAnnual herbaceous plant
HabitatCroplands, gardens, waste areas
Height1 to 6 feet tall
LeavesLong, narrow, green, or purple
FlowersSmall, inconspicuous, greenish-white, or reddish-brown
SeedsSmall, black, or brown, produced in large quantities
Seed viabilityUp to 40 years in the soil
Growth rateRapid, up to 3 inches per day
CompetitivenessHighly competitive with crops for resources
Ecological impactCan reduce biodiversity and alter soil chemistry
Control methodsMechanical removal, chemical herbicides, crop rotation
Economic impactCan reduce crop yields and increase production costs
ResistanceResistant to many common herbicides
Invaded regionsEurope, Asia, Africa, Australia

Some points to note about Pigweeds:

SeedlingsMost pigweed seedlings possess similar cotyledons (seed leaves). These cotyledons are usually long and narrow in shape and may even display a red hue on the undersides.
Mature PlantProstrate pigweed is a herbaceous annual plant that typically forms dense mats. Its dark glossy-green leaves have distinctive light-colored edges and its stems may be pink or red.
FlowersTumble pigweed stands out from other types of pigweeds due to its unique flower clusters that are found near the stem and leaf stalks, while other species such as Palmer amaranth feature flowers with spikes.
FruitsSingle-seeded fruits are minuscule capsules, measuring no more than 1.5 mm in length. When the fruit reaches maturity, it splits along its middle to release the seed.
SeedsSeeds are small, round, and glossy with a dark reddish brown to black finish. They measure between one-quarter to one-seventeenth of an inch in diameter.
ReproductionPigweeds are typically spread through the production of seeds. However, low amaranth is capable of re-growing from remnant pieces of its taproot and crown that remain in the soil after cultivation. This unique ability allows these weeds to survive certain types of harvesting methods.

How To Identify Pigweed (Amaranth)?

Identification of Pigweed (Amaranth)

There are various species of pigweed, including Palmer amaranth, smooth pigweed, prostrate pigweed, and redroot pigweed. It is a fast-growing, competitive weed that, if left unchecked, can reduce crop yields and quality. Therefore, it is crucial to identify it for effective plant management and control.

Here are some tips on how to identify pigweed (amaranth):


Its leaves are usually oval to diamond-shaped, with a pointed tip, and can range in size from 1-6 inches long. With smooth or slightly rough surfaces, they are frequently green or red. Some pigweed species have leaves that have pronounced white or light-colored veins, while others have leaves that are more uniform in color.


Pigweed stems are often green, although they can also be pink, crimson, or purple. They are often smooth or slightly hairy and can range from thin and flexible to thick and rigid.


Pigweed has small, inconspicuous flowers that are frequently green, red, or brown in color. Some species’ flowers are arranged in spikes or clusters, while others have flowers arranged along the stem or in the leaf axils.


Pigweed seeds are small and glossy and can range in color from tan to dark brown or black. They are often round or oval-shaped and can be either smooth or somewhat wrinkled.

Growth Pattern

Pigweed is an annual weed, which means that it germinates, grows, and produces seeds all in the course of a single growing season. It can reach a height of 6 feet, but it usually produces dense stands or low-growing mats that can easily outcompete neighboring plants.

Differentiate From Other Common Weeds

While identifying pigweed, it is also important to differentiate it from other common weeds like lambs quarters, redroot, and ragweed because they can have similar leaf forms and growth patterns. However, helpful tips and key features of pigweed have been described above to aid in distinguishing this weed from other weeds.

It is important to remember that variation in shape and form exists within each species, and some may even produce hybrids that may exhibit characteristics of both parents.

With this knowledge, you can identify pigweed and take action to properly control and manage this weed for optimal crop yields.

How To Control Pigweed (Amaranth)?

Pigweed is a common weed that can be difficult to control, as it is highly adaptable and can thrive in a variety of conditions. It can quickly become a problem in gardens, crop fields, and other agricultural areas. Controlling pigweed is important to prevent it from competing with other plants for nutrients, water, and sunlight, and to stop it from spreading to other areas.

Here are some methods for controlling pigweed:

1) Hand-pulling

This weed can be effectively controlled by hand pulling in small areas or on isolated plants. This method involves pulling the pigweed plants out of the ground by the roots. To prevent regrowth, it is important to make sure that all parts of the plant, including the roots, are removed.

2) Mowing

Mowing is a common method of controlling pigweed in larger areas. This method involves using a lawnmower or other cutting tool to cut this weed down to a few inches above the ground. This can reduce the plant’s ability to spread by preventing them from flowering and producing seeds.

3) Cultivation

The cultivation method involves using a hoe, tiller, or other tools to break up the soil and uproot pigweed plants. This method is effective when the plant is in the seedling stage and hasn’t established a deep taproot.

4) Crop Rotation

Crop rotation is an effective method of preventing pigweed from becoming established. Since this weed is an annual plant, it can be prevented by planting a different crop in the same area every year.

5) Mulching

Mulching with organic matter, such as straw or wood chips, around the plants can help restrict pigweed growth by blocking sunlight and preventing seeds from germinating. However, mulching may not be effective for controlling large infestations.

6) Chemical control

Herbicides can be used to control pigweed in larger areas or when other methods are not effective. There are various types of herbicides available, and the choice of herbicide will depend on the type of pigweed, the location of the infestation, and other factors.

In order to avoid harming non-target plants and to protect both human and environmental health, it is important to carefully read and adhere to the label instructions while using herbicides.

7) Prevention

Prevention is the best way to control pigweed. This involves

  • Minimizing soil disturbance
  • Maintaining healthy soil
  • Removing weeds before they can produce seeds
  • Planting competitive crops or groundcovers that can outcompete pigweed

Furthermore, using clean seeds and equipment can prevent the introduction and spread of pigweed in new areas.

What Are The Types of Pigweed (Amaranth)?

Types of Pigweed (Amaranth):

Pigweed is a common term used to describe a collection of weeds from the genus Amaranthus. There are many species of pigweed, and they can be found throughout the world in a wide range of habitats. Listed below are some of the most common types of pigweed:

1) Redroot Pigweed (Amaranthus Retroflexus)

Redroot pigweed is commonly found in agricultural fields, gardens, lawns, and along roadsides. It is easily identified by its deep red tap root, which appears during the seedling stage of the plant’s growth. It stands upright and can reach a height of 3-4 feet, but can sometimes grow taller.

Its leaves are alternate, ovate, and have a slightly pointed tip. The leaves have noticeable veins and are covered in tiny hairs. Immature leaves may appear purplish on their underside.

In addition, its flowers are monoecious, meaning that both male and female flowers are present on the same plant. The male flowers are located at the top of the inflorescence, while the female flowers are located at the base. After pollination, the female flowers develop into small, dark brown seeds that are roughly 1/16 inch in diameter.

Due to its rapid growth and tolerance to herbicides, redroot pigweed can be a difficult weed to control. However, a combination of mechanical, cultural, and chemical control methods can be effective in managing its growth and preventing it from becoming a major weed problem.

2) Prostrate Pigweed (Amaranthus Blitoides)

Prostrate pigweed has a flattened growth habit that distinguishes it from other pigweed species, and it is often found in open, disturbed areas, such as roadsides, pastures, and crop fields.

Despite their size, the branches can reach up to two feet long. The leaves are narrow towards their base and have a spoon-like shape. They measure less than 1.5 inches in length and appear dark green and waxy. Stems are known to be smooth and succulent, often exhibiting a vibrant red hue. Male and female flowers grow on the same plant but not in the typical terminal spike pattern. Instead, they bloom in clusters within the leaf axils.

There are many ways to control this weed, including cultural, mechanical, and chemical methods.

The use of cover crops, good irrigation techniques, and keeping healthy soil with the right nutrient levels and pH are all examples of cultural control approaches that stop the development and spread of prostrate pigweed.

3) Tumble Pigweed (Amaranthus Albus)

Tumble pigweed is an annual weed and is commonly found in agricultural fields, gardens, lawns, and disturbed areas. It has a shrubby growth pattern and typically grows up to around 3 feet tall with several branches. Its leaves are typically small, approximately 1.5″ long and 1 inch wide, and are shaped like an egg with slightly wavy edges. Its stems are erect, smooth, and usually light green in color. Additionally, it is a monoecious species where inflorescences of flowers appear in spiny clusters in the leaf axils as opposed to terminal flower spikes.

It thrives in areas with high levels of moisture, like floodplains, irrigation ditches, and other areas where water is readily available, but can also tolerate drought conditions.

Mechanical control methods, such as pulling or hoeing, can be effective for small infestations of tumble pigweed. However, chemical control methods, such as the use of pre-emergent or post-emergent herbicides, may be required for larger infestations.

4) Waterhemp (Amaranthus Rudis)

Waterhemp is an upright and fast-growing species of pigweed. It can grow up to 10 feet tall but is typically around 5-7 feet tall. It has smooth, hairless stems that are usually green or reddish-brown in color. Its leaves tend to be dark green and shiny and come in a variety of shapes, including elliptical, oval, and lanceolate. The leaves are often longer than they are wide and can grow up to 6 inches in length.

Unlike certain other types of pigweed, Waterhemp plants have male and female flowers situated on separate plants (it is dioecious). The male flowers are typically found on long, unbranched flower spikes, while the female flowers are found in the upper leaf axils.

Waterhemp can be controlled through a combination of cultural, mechanical, and chemical control methods. Cultural practices, such as crop rotation, can help reduce Waterhemp infestations.

5) Palmer Amaranth (Amaranthus Palmeri)

Palmer amaranth is a tall pigweed species, growing up to 6-8 feet in height. Its stem is thick and strong and can range from green to red in color. Its leaves are typically dark green and feature different shapes, including egg, diamond, or lance-shaped. The leaves have a distinct white or purple, chevron-shaped watermark on their upper surface, which is a useful diagnostic feature to distinguish it from other pigweeds.

Unlike other weeds, Palmer amaranth produces male and female flowers on separate plants making it a dioecious species. Female flowers can be distinguished from water-hemp by their sharp bracts and are typically found on long flower spikes that grow up to 2-3 feet in length and arise from upper leaf axils.  On the other hand, male flowers are usually borne on smaller spikes that grow from the lower leaf axils.

Palmer amaranth is considered one of the most problematic weed species in modern agriculture. It poses a significant danger to agricultural output all over the world because of its ability to rapidly develop resistance to herbicides and its prolific seed production.

To manage this weed, an integrated approach is recommended. This includes a combination of cultural, mechanical, and chemical control methods. Chemical control methods may include the use of herbicides, but resistance management strategies should be followed to prevent the development of herbicide-resistant populations.

What Are The Benefits & Uses Of Pigweed (Amaranth)?

Benefits & Uses of Pigweed (Amaranth):

Pigweed (or amaranth) is often considered a weed and is widely regarded as invasive. However, it also has a number of potential benefits and uses.

1) Nutritional value

For those who are passionate about bringing the best of nature’s bounty to their table, pigweed is an excellent choice. It is incredibly nutritious and contains a wide range of vitamins and minerals, including calcium, iron, magnesium, and vitamins A and C. It is also a good source of protein and dietary fiber.

2) Culinary uses

Pigweed leaves can be enjoyed raw in salads or cooked like spinach as a nutrient-rich vegetable. The seeds can also be ground into flour for baking purposes or popped just like popcorn for a delicious and nutritious snack. Just remember to thoroughly wash all plants before consuming them, in case they were previously treated with chemicals.

In some communities, this plant is considered a traditional cuisine and is used in a variety of dishes, such as soups, stews, and salads.

3) Medicinal uses

Pigweed has been used in traditional medicine for centuries to treat a range of illnesses, including skin conditions, respiratory issues, and digestive issues. Some studies have suggested that this plant may have anti-inflammatory and anti-cancer properties, but more research is required to fully understand its potential health benefits.

4) Soil improvement

This plant belongs to the Amaranthaceae family, which is renowned for its capacity to retain nutrients from the soil. Thus, it can be used as a natural fertilizer and could enhance soil quality.

5) Pollinator habitat


Pigweed is an important plant for fostering biodiversity and sustaining regional ecosystems because its flowers are a source of nectar for bees and other pollinators.

This plant may have some potential benefits, but it must be properly managed to prevent it from spreading and harming the ecosystems in the area.  Also, before utilizing this plant for medical purposes, it is also important to consult with a doctor.

So, with this, we have discussed everything you need to know about pigweed. Hope you enjoyed reading this article.

Frequently Asked Questions

How to get rid of pigweed?

If you have pigweed growing in your lawn, a pre-emergent herbicide is a great way to manage it. It will prevent new seedlings from sprouting, while also killing existing weeds.

Alternatively, combination products are available that combine both pre- and post-emergent ingredients. Nonselective herbicides, such as glufosinate-based solutions, are effective. But it should always be used with caution as they will kill all plants – including the grass – within their range. It is important to read and follow the label directions on any product you use to ensure safe and effective application.

Why do Lawns Get Pigweed?

Weeds are always on the lookout for an opportunity. If there’s a chance, they will seize it. Thin lawns that lack turf density provide the perfect opportunity for weeds like prostrate pigweed to take root. These unwelcome intruders signify that your lawn is lacking in vital nutrients. To ensure a lush and healthy lawn, make sure to fertilize and maintain optimal soil moisture levels.

Is pigweed harmful to humans?

While pigweed is not toxic to humans, it can be a major weed in agricultural fields and gardens, reducing crop yields and causing significant economic damage. Moreover, some people may have allergic reactions to pigweed pollen.

Can you eat pigweed?

Yes, pigweed leaves and seeds are edible and are used in many cultures as a food source.

But, it is important to properly identify the species and prepare it correctly, as some species may contain high levels of nitrates or oxalates that can be harmful if consumed in large quantities.


1) Pigweeds – Agriculture and Natural Resources, University of California


2) Pigweed Identification – Agriculture and Natural Resources, University of California


3) United States Department of Agriculture (USDA) Plants Database


4) Iowa State University Extension and Outreach



5) Michigan State University


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