Common Sonoma County Weeds in the Home Garden
Manage these spring weeds when young, without the use of chemicals.
|Bittercress (Cardamine spp.) includes two species (C. oligosperma and C. hirsuta) that can be a problem in home gardens. These are mainly winter annuals with pinnately-compound leaves, tiny white flowers, and linear seed pods. When dry, these pods will aggressively fling seeds away from the parent plant to disperse them. Continuous manual removal of plants before seeds are produced will help control the species. For more information, click here.
|Italian thistle (Carduus pycnocephalus) is an annual or biennial weed that is first noticeable as a basal rosette of irregularly toothed and prickly leaves. As the plant matures it sends up a prickly, winged shoot, up to 6 feet tall, topped by a cluster of 2-5 small flowers with spiny bracts and delicate pink or purple petals. These thistles are easily controlled by digging up the tap root of the rosette when the plants are small. For more information click here.
|Chickweeds, including mouseear chickweed (Cerastium glomeratum) and common chickweed (Stellaria media) are annual or perennial members of the pink family, identifiable by their opposite leaves and small white flowers with deeply lobed petals. These plants are controlled by manual removal and close mowing to limit seed production. For more information click here.
|Petty spurge (Euphorbia peplus) is an erect winter or summer annual characterized by its leafy green foliage, milky sap, and inconspicuous green flowers. This spurge and other annual species of Euphorbia are easily controlled by manual removal each year. For information on controlling petty spurge and other annual spurges, click here.
|Cutleaf geranium (Geranium dissectum) is an annual or biennial plant identified by its rosette of roundish, highly dissected leaves on stalks, and tiny violet-pink flowers. Annual, manual removal before these plants goes to seed is an effective means of control. For more information click here.
|Prickly lettuce (Lactuca serriola) is a winter or summer annual, identified by its narrow stock, prickly leaves, and small pale-yellow flowers. The tiny seeds are topped with a fluffy white pappus, allowing them to parachute away from the parent plant. Manual removal or mowing before the seed matures is an effective means of controlling prickly lettuce. For more information, click here.
|Common mallow or cheeseweed (Malva spp.) includes several annual, biennial or sometimes perennial species identified by their low growth form; rosettes of rounded, shallowly lobed leaves; minute pink, white, or lavender flowers; and small fruits shaped like wheels of cheese. Manual removal, particularly in spring when the soil is still damp and before seeds are produced can control mallows. For more information, click here.
|Bermuda buttercup (Oxalis pes-caprae) is a low-growing, herbaceous perennial with shamrock-like leaves and yellow flowers on stalks. This species reproduces by bulblets and is very difficult to control, but a consistent program of annual removal just as plants are starting to flower can be effective over time. For more information, click here.
|Common groundsel (Senecio vulgaris) is a common winter or summer annual identified by its erect, single or branched stem with deeply lobed leaves with toothed margins, and cluster of tiny yellow flowers that develop into seed heads with a fluffy white pappus that aids in dispersal by wind. Manual removal before plants have gone to seed is an effective means of controlling this weed. For more information click here.
Manage these summer weeds before they produce seed, without the use of chemicals.
|Poison hemlock (Conium maculatum) is similar in appearance to carrots and celery but toxic if ingested and may cause dermatitis if handled. It can usually be identified by the presence of purple spots or streaks on the stem although some individuals lack this trait. Annual removal by hand pulling, cutting the stem at ground surface, or mowing before it produces seed will control poison hemlock over time. Be sure to wear gloves when handling. For more information, click here.
|Field bindweed (Convolvulus arvensis) is a herbaceous perennial plant with arrowhead-shaped leaves and an extensive system of deep, creeping roots. The vining stems of bindweed spread along the ground or wind through other plants, binding the foliage as they grow. This plant is extremely difficult to control. Deep cultivation before flowering and repeated cultivation when new shoots appear is somewhat effective if done on a regular basis. For more information click here.
|Willowherb (Epilobium spp.) includes several native species that can become weedy in the garden. Depending on the species, willowherbs may be perennial or annual, but both kinds are tall (up to 6 ft), and single stemmed or bushy in appearance, with small flowers and slender capsules that bear seeds. Willowherbs can be controlled in the garden by hand pulling or cultivation before they set seed. For more information click here.
|Catchweed bedstraw or cleavers, (Galium aparine) is an annual plant with square stems, whorled leaves, and inconspicuous flowers. It is found intertangled in or climbing on other plants in the garden. The foliage and fruits are covered with tiny curved prickles that cling to clothing and fur. Manual removal or cultivation before plants develop fruits will control this plant. For more information, click here.
|Herb-Robert (Geranium robertianum) is an annual or biennial plant with malodorous, dissected foliage, small pink flowers, and a slender taproot. This plant will grow in open or shady areas, and may hide beneath the foliage of other plants in the garden. Like other geraniums, herb-Robert should be pulled, dug up, or cultivated before flowers and seeds are produced. For more information click here.
|Foxtails (Hordeum marinum and H. murinum), also known as Mediterranean and hare barley, are annual grasses with dense, bristly spikes. Mature foxtails have stiff, barbed awns that are hazardous to pets if consumed, inhaled, or lodged in ears. Small infestations can be removed by digging or hand pulling. Larger areas should be mowed prior to spike formation. For more information, click here and here.
|California burclover (Medicago polymorpha) is an annual plant with stems up to two feet long that usually trail along the ground, creating dense mats. Burclovers have leaves comprised of three leaflets and small yellow flowers that mature into a prickly bur. Burclover can be controlled by hand pulling, hoeing, cultivation, and application of mulch. For more information click here.
|Wild radish (Raphanus raphanistrum, R. sativus) are annual or biennial weeds that exist as rosettes until a stout, often woody flower stem develops. The small, pale flowers vary in color and have four petals arranged in a maltese cross formation. Control by digging up the rosettes before they bolt. Larger plants should be removed by shovel or cut at the base before flowering. For more information, click here.
|Red Sorrel (Rumex acetosella) is a herbaceous plant with arrowhead-shaped leaves, trailing stems and creeping roots. Clusters of tiny flowers mature into a reddish-brown head of grain-sized, three-sided fruits. Sorrel both reproduces by seed and spreads by creeping roots. It is difficult to control but can be kept in check by periodically digging up the plants, removing as much of the root system as possible. For more information, click here.