Pigweed
Broadleaf weed
Pigweed is the common name for several fast-growing annual plants in the Amaranthus family, including redroot pigweed, smooth pigweed, and the aggressive Palmer amaranth. Gardeners and growers notice it because it germinates through the warm season, grows quickly, and produces enormous numbers of seeds. It is one of the most common and troublesome broadleaf weeds in lawns, gardens, and crop fields across the United States.
How to identify it
Pigweed leaves are oval to diamond shaped with smooth edges, arranged alternately along the stem, and often have a slightly wavy surface and prominent veins. Young plants form a low rosette, then send up a stout, upright central stem that can reach several feet tall, sometimes with a reddish tinge near the base. Its flowers are small and greenish, packed into dense, bristly spikes at the stem tips and where leaves meet the stem. Many types, especially redroot pigweed, have a thick reddish or pink taproot, which is a helpful clue when you pull a plant.
Where it grows
Pigweed thrives in disturbed, sunny, fertile ground such as vegetable gardens, thin lawns, field edges, roadsides, and cropland. It is a warm-season annual that sprouts from late spring through summer once soils warm and continues until frost. It spreads entirely by seed, and a single large plant can produce hundreds of thousands of tiny seeds that stay viable in the soil for years, building a long-lasting seed bank.
Why it is a problem
Pigweed grows tall and fast, shading and out-competing crops, vegetables, and turf for light, water, and nutrients, which can sharply reduce yields. Its heavy seed production lets a small infestation explode into a widespread problem within a season or two. The pollen is a known contributor to hay fever, and the foliage can accumulate nitrates that make it hazardous to grazing livestock in some conditions.
How to manage it
The most effective approach is to stop plants before they set seed, since preventing seed is the key to shrinking the problem over time. Hand pull or hoe young plants when the soil is moist and the taproot comes up easily, and remove them before the flower spikes mature. A layer of organic mulch in garden beds blocks light and greatly reduces new seedlings, while a dense, healthy lawn and vigorous crop stand crowd out weeds before they establish. Keep tools and equipment clean, avoid moving contaminated soil, and mow or cut regrowth in field edges to keep any survivors from producing seed.
Commonly confused with
Young pigweed is easily confused with common lamb's quarters, which has a whitish, mealy coating on its new leaves rather than the plainer, sometimes hairy foliage of pigweed. It is also mistaken for edible amaranth relatives and for waterhemp, a close cousin that has narrower, hairless leaves and no reddish taproot.
General guidance for US lawns and gardens, focused on prevention and non-chemical control. For a confirmed identification and options specific to your area, contact your local Cooperative Extension office. Page updated Aug 4, 2026.