The most common weeds in California include grassy varieties such as Johnson grass and foxtails. Among the most prevalent broadleaf weeds are plants that can be toxic if ingested, like poison hemlock, as well as those with nutritional value, such as dandelions.
This list of weeds will help you know what’s lurking in your yard and the plant’s growing preferences.
Types of grass weeds in California
Johnson grass (Sorghum halepense)
Johnson grass is considered one of the most problematic perennial grasses. It grows fast and competes aggressively with crop plants but is also found in gardens, roadsides, and fields. It grows in the Cascade Range foothills, Central Valley, western California, and the Sierra Nevada foothills to about 2,600 feet.
Description: The bright green leaves have a vein in the middle and are narrow and smooth. The stems are reddish closer to the base and can grow up to 7 feet tall. Greenish flowers turn reddish or purplish upon maturity. Flowers blossom from May until mid-fall or October.
Quackgrass (Elytrigia repens)
Quackgrass is found across California up to elevations of 5,900 feet. It is more prevalent in the northern part of the state and coastal areas and not typically found in the deserts.
Although the weed prefers sandy and loamy soils, it thrives in multiple soil types, alkaline, and saline conditions. Quackgrass is hard to get rid of once it is established.
Description: It has coarse, flat, long leaves that are bluish-green and grow between 1 and 3 feet tall. The spiked flower heads are flat and appear from May through September.
Crabgrass (Digitaria)
Crabgrass grows throughout California but mainly at lower elevations, particularly in veggie gardens, flower beds, and lawns. Crabgrass is typically not found in dry areas during the summer.
Description: This weed grows up to 6 inches when unmowed and up to about 2 feet tall when mowed. The dark green leaf blades are smooth and pointed. Whorled spikes that are 2 to 6 inches long produce flowers and seeds.
For how to deal with this stubborn weed, check out How to Get Rid of Crabgrass.
Foxtail (Setaria spp.)
Yellow and green foxtails are of the genus Setaria and both are found in the state. Yellow foxtail (Setaria pumila) grows throughout California. This weed loves disturbed areas, like roadsides, orchards, cropland, and gardens and is found in the central-western area, Cascade Range, and elevations up to about 3,900 feet in the Sierra Nevada.
The University of California Integrated Pest Management Program reports that green foxtails (S. viridis) are found in “low-lying and foothill areas of California, except in the Mojave Desert and Great Basin, to about 1,000 feet.”
Foxtails are one of the most common weeds found in Sonoma County home gardens. The barbed, stiff awns of full-grown foxtails are harmful to pets if consumed or inhaled.
Description: Foxtails have a cylinder, hairy seed head with a soft texture. The inflorescences have spikelets and look like a fox’s tail. Yellow foxtail is smaller, has an erect seed stalk, and only grows to about 1 to 3 feet.
To find out how to remove annual weeds like foxtail, see our guide, How to Get Rid of Weeds in Flower Beds.
Annual bluegrass (Poa annua)
You’ve probably seen annual bluegrass growing in fields and roadsides or your garden, lawn, or other areas of your landscape. It is one of the most common weeds found across California. Annual bluegrass is most prevalent in coastal areas at levels up to 6600 feet.
This cool-season winter grass prefers shady yards with high moisture. Bluegrass dies back in hot and dry weather.
Description: It grows up to 6 to 8 inches and has silverish to white-colored seed heads that are typically always visible. The stems usually bend at the base and the leaves are crinkled closer to the base. Flowers may be a pale, purple, or green color and sprout between December and July.
Lawn Love’s article, How to Control Annual Weeds vs. Perennial Weeds, gives effective strategies for controlling winter annual weeds.
Bermudagrass (Cynodon dactylon)
Although bermudagrass is one of the most commonly used turfgrasses for lawns, it becomes an unwanted weed when it invades gardens. Warm temperatures and moist weather cause Bermudagrass to grow rapidly. It is found across the Golden State to elevations of approximately 2,900 feet, particularly in the Great Basin area.
Bermudagrass spreads by seeds and stolons, making it difficult to eradicate.
Description: The stems grow as high as two feet. Leaves are linear and the lower surface is hairy; the upper side is not as hairy. The inflorescences at the stem tips have three to nine spikes.
See Lawn Love’s guide, How to Control Weeds by Type, for management tips.
Types of broadleaf weeds in California
Prickly lettuce (Lactuca serriola)
Prickly lettuce is found throughout the state up to elevations of 6,600 feet. It is a winter annual or biennial plant in California, and the winter rains cause this weed to germinate. Prickly lettuce is common across the state and one of the most common weeds in Sonoma County. Manage this weed by mowing it before the seed matures.
Description: The small yellow flowers that bloom from April through October look like dandelions. When the flowers bloom, the rosette foliage from an immature plant may look damaged or may be missing. The bottom of the stems can be smooth or have hard bristle-like hairs. Leaves are deeply lobed with prickly edges. Mature plants have dark, deeply green colored leaves.
Cutleaf geranium (Geranium dissectum)
This weed is found throughout California to approximately 3900 feet, except for the Great Basin and the deserts. Cutleaf geranium grows in grasslands and can compete with native plants for water and other nutrients.
Description: The rosette leaves are rounded, palm-shaped, distinctively dissected, and attached to long stalks. Flower stems appear in the spring, are rough and fuzzy, and grow about 2.5 feet long. The stem leaves are thinner than the stalk leaves. Flowers bloom from March through October and have five purplish-pink petals that cluster in twos on the stems.
Poison hemlock (Conium maculatum)
Poison hemlock is located throughout the state at elevations 3300 feet and less. It is absent from the Modoc Plateau and desert areas. This weed can cause skin irritation so handle it with gloves. It is also toxic to the skin and if eaten can be fatal in small amounts. You can control this plant by mowing it before seed development or cutting the stem at the ground.
Description: This weed looks like carrot and celery plants. Some poison hemlocks have purple marks on the stem. The initial true leaves when the plant is young look like parsley leaves. When mature, the leaves are triangular and separated into leaflets that are divided multiple times or lobed. Young and mature foliage smell musty when crushed. Several small, white, umbrella-shaped flowers cluster at the ends of stems from April through July.
Filaree, whitestem (Erodium moschatum)
Filaree grows close to the ground and can be found throughout California up to about 4900 feet. It is not usually found in the Great Basin and desert areas. Filaree is a winter annual and in some cases, it is a biennial. Filarees (Erodium spp.) are one of the most common weeds located in southern California.
Description: Pink, lavender or reddish flowers bloom from about February through May but may appear earlier or later. Flowers have five petals that grow at the tips of the stalk. Stems are pale green to whitish. This weed’s lacy leaves make it an attractive plant. Leaves are deeply lobed and lay nearly flat on the soil. Rosette leaves are separated into leaflets.
Mallow (Malva parviflora)
This winter annual is also called cheeseweed because its seeds resemble cheese wheels. You may have seen the heart-shaped leaves invading sections of your lawn. It is easier to treat mallow when young because the weed’s taproot is very strong. But even when young, the taproot makes removal challenging.
Mallow grows across the state to an elevation of about 4900 feet, with the possible exception of the Great Basin. This weed is one of the most prevalent in southern California.
Description: Its hairy green leaves are slightly palm-shaped and grow on erect stems 2 feet long. The foliage has five to seven shallowly lobed sections. Small white or pale flowers grow in clusters at the bottom of the leaf stalks. Flowers are visible almost year-round.
Common groundsel (Senecio vulgaris)
Common groundsel grows across the state at elevations below 4,900 feet, except for deserts. Although it is a winter annual, groundsel can grow year-round in coastal regions. This weed is more troublesome when there are periods of cool and moist weather. Prolonged hot, dry conditions kill the weed.
Groundsel can outcompete recently planted seeds for necessary nutrients. This plant is toxic to humans and livestock when ingested.
Description: Common groundsel has jagged hairy leaves with toothed edges and yellow flowers that look like daisies. Flowers are visible almost year-round and develop seed heads that have fuzzy, white floating seeds. The seed heads also resemble daisy seed heads.
Creeping woodsorrel (Oxalis corniculata)
Creeping woodsorrel grows fast, is very competitive, and persists year-round. It prefers partly shaded lawn areas and or perennial low-growing plants. This perennial thrives in well-drained and fertile soil. Woodsorrel is found throughout the state.
Description: Foliage has three heart-shaped lobes. The leaves and stems may have a reddish look. Small, bright yellow flowers with five petals develop and are present nearly year-round.
Common purslane (Portulaca oleracea)
Common purslane has thick, fleshy leaves that form a dense mat. This warm-season annual outcompetes other plants by absorbing moisture and light before they reach the ground. Seedlings are unable to receive the water and sunshine needed to grow.
Description: The mature plant has succulent branches and typically has egg-shaped succulent leaves with a little red around the edges. The foliage appears opposite one another along the stem. Yellow, five-petaled flowers bloom from May through September. The flowers usually only open from mid-morning to early afternoon when the day is sunny and hot.
White clover (Trifolium repens)
This creeping perennial weed develops white flowers most of the year, from March through December, that stick out above the turf grass. The variegated leaves are oval-shaped. This plant is found across California, except for deserts.
Description: Foliage has three leaflets. The weed has branching stems that grow along the ground. A cluster of white or light pink flowers resembling the shape of an egg develops from March through December.
Italian thistle (Carduus pycnocephalus)
Italian thistle is a noxious weed in California. Some of the areas it grows in include the Central Coast, the San Francisco Bay area, and the southern North Coast. This weed can crowd out native plants, and its sharp spines can deter livestock and wildlife from entering the vicinity.
When the weed is young, it is easily removed by pulling out the taproot.
Description: Rosette leaves are prickly and toothed. When the plant is mature, it develops a long spiny shoot. Small purple or pink flowers cluster in groups of two to five atop the shoot. The flower heads have spiny bracts and a rough surface. Petals bloom from February through July.
Field bindweed (Convolvulus arvensis)
Field bindweed is commonly found in agricultural fields in temperate areas. It is very damaging to crops, especially beans and potatoes. Field bindweed is prevalent in California and grows at elevations up to approximately 5000 feet.
Description: This weed has long stems that form a mat on the ground or climb up other plants, like shrubs. The foliage is shaped like a bell or spade. When the plant matures, the leaves are lobed at the base. White to purplish-white trumpet-shaped flowers bloom from about April through October.
Common chickweed (Stellaria media)
Chickweed can persist year-round in foggy coastal conditions, but it is mostly a winter annual in the rest of the state. Its habitat is most of California at elevations up to 4300 feet; chickweed is typically not found in the Mojave Desert. The weed is one of the most common weeds in Sonoma County.
This weed can carry several pests and diseases that adversely affect many veggie crops. On the other hand, chickweed is a food source for many types of California wildlife and has been used for medicinal purposes for humans.
Description: It is low-growing and has egg-shaped leaves. The stems are green. Little star-shaped white flowers separated like rabbit ears develop.
Find out prevention and elimination techniques for chickweed in our guide, What is Chickweed and How to Get Rid of It.
Dandelion (Taraxacum)
Dandelions are found all around California up to about 11,000 feet, except in the deserts. This weed is very common in turf and mountain meadows in southern California. Dandelions carry aster yellow disease, which can impact many types of vegetable plants.
But dandelions are also edible. The leaves make bitter salad greens, while the flowers have been used to make wine, and the roots and flowers are used to make tea. I’ve enjoyed both the salad greens and a root tea after purchasing dandelions from the farmer’s market or herbal shop.
Description: Dandelions have spear-shaped leaves that can be hairy or barely hairy. Yellow flowers sit atop stems and become a white fuzzy ball of bristles disbursed by the wind.
Find out more about dandelions:
More resources for your California lawn care and landscaping
Lawn Love has a number of guides to help you maintain your yard and keep it looking healthy and attractive:
- 5 Best Grass Types for California Lawns
- 27 California Native Plants
- Top 15 FAQs about California’s Green Lawn Care Law
- California’s Green Lawn Care Law
- When to Fertilize Your Lawn in California
Get help from a pro
Although this article helps you identify several common weeds, many more grow in California. You want to be certain about what is growing in your grass and garden so that you can treat it effectively and ensure that your treatment method is as safe as possible. Let a Lawn Love pro assess your infestation and determine the safest and most effective solution.
Main Photo Credit: Poison hemlock (Conium maculatum). Eric Coombs, Oregon Department of Agriculture, Bugwood.org | Wikimedia Commons | CC BY 3.0
Related Posts:
