- Author: Anne Schellman
- Contributor: Karey Windbiel-Rojas
People in urban and suburban areas often use the term “invasive” to describe plants or weeds that appear to take over a garden or landscape. However, true invasive plants are weeds that infest ecosystems, rangelands, and pasture—places common garden weeds don't thrive.
Invasive plants can reduce native plant and animal diversity, threaten endangered species habitat, and increase wildfire and flood danger. Most invasive plants were introduced as ornamentals from the retail nursery industry, or for the purposes of soil stabilization, animal forage, human food, fiber, or medicinal plants. Some may still be found for sale at retail nursery and garden centers, including the following:
Nutgrass, also called nutsedge, could easily be one of the top 5 nuisance weeds gardeners deal with in the garden and landscape. While we don't know that for sure, we do know that nutsedge is a very challenging weed to control.
Yellow and purple nutsedge are the two species most often found in California. Yellow nutsedge grows throughout the state, while purple nutsedge is found mostly in southern California.
Nutsedge is difficult to control because the plants form small underground tubers and rhizomes. Most of these tubers are found in the top six inches of the soil but can also be found even deeper. Removing the tubers by hand is the best way to remove small plants but may require continued monitoring and hand...
In mid-March, many people use clover-themed decorations in preparation for St. Patrick's Day. Many gardens and landscaped areas are “decorated” with clovers too, especially with recent rains and mild temperatures in much of California. For some people, clovers are considered weeds, but others enjoy the green color they bring!
Clovers begin to germinate in the fall and continue throughout winter and early spring. Their bright green leaves can blemish the look of lawns and may be unsightly when found in ornamental plantings.
Clovers growing in lawns or landscapes are often a sign of low soil nitrogen, so changing fertilization can help prevent their growth. Read the UC IPM publication
Not everyone has a lawn, but if you do, fall is the perfect time to give your lawn some much-needed attention. To find out if you are maintaining your lawn properly, answer the following questions:
- Is your irrigation system set to water deeply and infrequently?
- Do you regularly check and adjust sprinkler heads?
- When you mow, do you remove less than 1/3 of the leaf blade?
- Do you grasscycle to add nutrients back into your lawn?
- When needed, do you aerate your lawn and remove
Controlling unwanted trees, shrubs, and woody perennial grasses can be difficult in landscapes, gardens, and natural areas. These troublesome woody plants often resprout after being cut back, and the resprouting shoots can outnumber the original plants. Some woody weed plants are natives but in certain settings can create fire hazards and become problematic to human health and movement.
So how can you manage plants like ivy, bamboo, and poison oak?
A new version of Pest Notes: Woody Weed Invaders, authored by UC Davis plant scientists Joseph DiTomaso and Guy Kyser, is now available online and in print. Use this guide to find answers to the...