Identifying Weeds

• Once you identify a weed and understand how it grows, you can make better decisions about how to best eliminate it. Determining the weed type is the first step in identifying specific weeds. Common weed types include grass weeds, broadleaf weeds, sedge and aquatic weeds. Online resources, such as the University of California Integrated Pest Management Program's weed photo gallery, offer ways to help identify weeds.
  
  

Grass Weeds

• Weeds that look like grass have thicker blades and stalks than regular grass and grow in a thick bunch. They have strong root systems and are spread by underground rhizomes, or root stems, and by seeds. Grass weeds come in both perennial (return year after year) or annual (live through one growing season only) varieties. Northern California lawns are prone to crabgrass and look-alikes goosegrass and bluegrass. Fortunately, these annuals die out in winter. They can also be contained by keeping grass well-fertilized and 2 to 3 inches high. Bermudagrass and dallisgrass are special weed problems in California lawns. Because they are perennial, you will need to be diligent about identifying and removing these weeds. Use weed and feed formulas with a post-emergent (after seeds sprout) herbicide in fall, and pre-emergent (before seeds sprout) herbicide in early spring, to keep grass weeds from taking over lawns.
  
  

Broadleaf Weeds

• Remove broadleaf weeds by hand to protect garden plants.Hemera Technologies/AbleStock.com/Getty Images
  
  Broadleaf weeds have a variety of leaf types and are sometimes mistaken for domestic plants. The most common weeds have prickly, bristly and deeply divided lobes. The most troublesome types of broadleaf weeds send out deep taproots or rhizomes that spread underground and send up new growth, sometime several feet away from the mother plant. Broadleaf weeds attack above ground, too, by sending out runners that put down roots and start new plants. The list of common perennial broadleaf weeds in California lawns includes dandelion and clover, creeping woodsorrel, English daisy and plantains. Common annual broadleaf weeds include knotweed, burclover and spurges. Clover will take over areas low in nitrogen, so fertilize lawns at proper intervals with a high nitrogen formula to fend it off. Using chemical formulas to remove broadleaf weeds can also affect lawns and gardens. Hand removal is the best defense against broadleaf weeds. Try some of the new ergonomic weed-pulling tools before assaulting weeds with chemicals.
  
  

Sedge and Aquatic Weeds

• Sedges look like tall grasses but have dense, triangular stalks and spindly leaves arranged in clusters of three. These weeds have strong, fibrous roots and can spread by way of aboveground stolons, rhizomes or tubers (small bulbs). Common sedge weeds -- such as green kylinga and nutsedge -- and aquatic weeds -- such as cattails and rushes -- are found in wet soil and shallow water areas, mostly in northern California's coastal wildlife refuge areas.