Contrary to what my neighbors might say, my front lawn is not a weed demonstration garden. In fact, I actually do not have very many species of weeds in the garden. Those that are present just happen to be very obvious.

Weeds are defined as ‘plants where they do not belong’. This is a very broad definition which applies to many exotic (Imported) species that naturalize, including trees such as blue gum eucalyptus and bailey acacia. Many exotic species that have become familiar weeds have been imported by accident. However, many have been imported as forage crops, lumber crops or ornamentals. In the Santa Clara Valley, there are not any native weed species that I can think of.

Most garden enthusiasts are not concerned with tree weeds, but the voracious annuals and perennials that are often difficult to eradicate once they have become established. Of course some require considerably more attention than others. Some, particularly the perennials, are often difficult to remove completely, and can easily grow back from parts left in the soil.

Bermuda grass is one of the most bothersome weeds and can be difficult to remove. It has become widely distributed because it was once commonly used as a lawn grass. In fact, my lawn is composed of ‘dwarf Bermuda grass’. It creeps both at the surface of the soil and below the surface with subterranean stems known as stolons. If the grass is removed at the surface, it quickly grows back from the stolons. Bermuda grass is very difficult to remove if it has become intermingled with the roots and lower limbs of shrubbery.

Yellow oxalis also grows back quickly from roots and bulbs. The problem I had with it is that I left it because the neighbors thought it to be attractive. Unfortunately, the flowers set seed very quickly. Removal of the plants is advisable to slow the dispersion of seed, but will not eradicate it. Digging of subterranean parts or application of chemical herbicides is usually necessary. If digging is preferred, it will be necessary several times to include those that survived previous procedures.

Portulaca (the weed form) does not grow back from subterranean parts, but may seem as difficult to eradicate because of the profusion of seed. It will be much more easy to control if plants are removed as they appear, before setting seed. Portulaca does not compete well with other species, but can be a serious problem in areas of partially exposed soil, such as rows in vegetable gardens. Spotted spurge behaves rather similarly.

Dandelion is not as common as it once was, mainly because of the dense growth of contemporary lawn grasses. They are still somewhat common in sparser lawns or in other areas of the landscape. When one becomes established, it can produce a profusion of seed very quickly. Mature plants exhibit long, thick taproots that usually break when the tops of the plants are pulled. New plants quickly grow back from the broken root tips. When they grow in expansion joints in concrete, removal of the taproot is nearly impossible.

Of course, there are more weeds than I can describe. Most should be removed as soon as they are noticed, before they become a serious problem. Unfortunately, chemical herbicides are often the best option. Most herbicides are selective, which means that they are specific to a particular type of weed. Modern products that are commonly available at nurseries, garden centers and hardware stores are very efficiently labeled for their recommended use.