Ann Wright: Garden weeds – good or bad?
The existence of weeds evokes a number of human reactions – dread, anger, complacency, defensiveness, tolerance, acceptance. Well, in some gardens, maybe not acceptance. It is hard to accept that the weeds seem to be destined for world domination. Especially the bermuda grass and bindweed in my garden which requires an annual reevaluation of why I love to garden.
Furthermore, the world of weeds is adrift with perspectives — what is one person’s weed, is another’s favorite flower. For example, henbit, also known as red deadnettle, (Lamium amplexicaule) may be unwelcome by some gardeners, but to another henbit is lovely and poetic.
The definitions of weeds may vary – from plants that are growing where they are not wanted, to those whose undesirable qualities outweigh the good. In some gardens, a weed is a plant out of place or unintentionally sown, or that gets in our way. Ralph Waldo Emerson once penned, “What is a weed? A plant whose virtues have not yet been discovered.”
Our understanding of weeds generally highlights the negative characteristics of weeds. Weeds compete for nutrients and water in our gardens, and can block sunlight and choke out desirable plants. Weeds surrounding the trunks of trees can harbor pests and promote disease, some harbor over-wintering pests.
Despite the negative attributes of weeds, some plant scientists counter with some beneficial qualities, such as holding the soil, preventing erosion and breaking up compaction. Many weeds also offer great sources of pollen and nectar for bees and other beneficial insects, as well as providing habitat for microbes within the soil. Many are cultivated for medicinal or nutritional purposes.
Regardless of perspectives and attitudes towards weeds, their emergence this time of year poses a challenge to even the most seasoned gardeners. There are many ways to manage these unwelcome plants that crowd our new seedlings.
Integrated Pest Management (IPM) offers several choices in managing weeds. Familiar to many gardeners, IPM helps gardeners solve pest problems using a process that minimizes risks to humans, animals and the environment. IPM includes as pests, plants, vertebrates, invertebrates, pathogens, or other unwanted organisms that may harm water quality, animal life or other elements in the ecosystem. A science-generated, decision-making process, IPM first requires observation and correct identification of the pest, followed by an assessment of the numbers or amount of damage caused by the pest. Guidelines are available from IPM sites to help gardeners decide which strategy or combination of strategies to enlist — such as biological, cultural, physical or chemical controls.
First, it’s critical to identify a pest – in this case, weeds which can be annuals or perennials and can be characterized as persistent and competitive, some with seed that can survive in the soil for a long time. To identify which weed may be invading your space, the UC IPM website offers an online tool which may help home gardeners identify weeds. The site places weeds into four categories: broadleaf (herbaceous, flowering); sedges (perennial grassy-like plants that grow in shallow water or very moist soil); grasses (narrow leaves with parallel veins and small, inconspicuous flowers); and aquatic plants (plants that grow in water for at least part of their life cycle). Each category includes a tutorial with pictures describing each type.
Once the weed is correctly identified, and with help from IPM sites, management of weeds may be considered. Options include mechanical/physical, biological, cultural, and chemical controls. Probably one of the most common methods is mechanical/physical which, put simply, is going out and pulling the weeds! UCANR weed scientists suggest that most weeds can be managed by hand-weeding, plus mulching, and other nonchemical methods.
To learn more about weeds and their control, plan to attend the UC Master Gardeners of Nevada County, free public outdoor workshop, “Weeds – The Good, The Bad, The Ugly”, Saturday, April 9, from 10 a.m. to noon at the Demonstration Garden on the NID Business complex (1036 W. Main Street) in Grass Valley. We will explore the history of weeds and how they fit into our landscape, problems and benefits of weeds, local common weeds, and management strategies using IPM methods.
Another strategy to avoid weeds is to plant in containers. To learn more, join Master Gardeners for the first outdoor workshop of our season, “Container Gardening” TODAY at 10 a.m. at the Demonstration Garden (address above). Perhaps your growing space is limited, or deer and other pests may be getting the better of you – perhaps growing in containers would be a good alternative. Almost any plant, including bulbs and herbs, can be grown in a container, if you know how to care for them.
Other Master Gardener activities this spring include more in-person public workshops, and our popular Spring Plant Sale is on tap for Saturday, May 7, from 9 a.m. to noon. As in the past, Master Gardeners are now busy growing hundreds of vegetable, herb and flower starts for sale. Mark your calendars now. Check our website often for more information about this and all our workshops at https://ncmg.ucanr.org/ .
Ann Wright is a Nevada County Master Gardener
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