Let's talk weeds - half a dozen good and six of the other type

Garden Weeds - half a dozen good and six pesky ones

Technically, the term weed is used to describe any plant that is unwanted and grows or spreads aggressively among cultivated plants, depriving them of space, sun, water, nutrients, etc. 

Let's take a closer look at the following 12 weeds most commonly found at the Willowgate Community Garden in Mountain View, California, all of which propagate easily - either by self-seeding or sending runners.

Half a dozen beneficial weeds 

1. Purslane (Portulaca oleracea) is a fast-growing ground-hugging annual plant whose seeds spread with the wind. The succulent leaves have a slightly tart or sour and salty taste and are used in many cuisines around the world, especially in salads, soups, stews, and tomato sauces.

2. Italian parsley (Petroselinum sativum), also known as flat-leaf parsley, is a very hardy leafy green biennial herb with serrated leaves and a fresh, slightly peppery taste. It's often used as a garnish, but it can also add flavour to many dishes, including salads, pasta, soups, stocks, sauces, and meats. Beware the seeds spread easily with the wind and it is easy to find all over the Community Garden

3. Arugula (Eruca vesicaria) is a cruciferous green leafy salad leaf with a distinctive peppery taste, most commonly eaten raw in salads or as a topping on other foods but it can be sautéed. Beware it self seeds year after year though admittedly the flowers are great for bees 🐝 and butterflies 🦋 

4. Borage (Borgo officinalis), also known as starflower, is an annual herb in the flowering plant family Boraginaceae that is heavily favoured by bees 🐝 . As a fresh herb, borage, with a cucumber-like taste, is often used in sparingly small quantities as salads or as a garnish. The flower has a sweet, honey-like taste and is often used to make herbal tea and decorate desserts and cocktails, sometimes frozen in ice cubes.

5. California poppy (Eschscholzia californica) became the official state flower of California in 1903, contrary to popular belief it is ok to remove poppy plants from the garden as there is no law protecting the California Poppy per se. Bees 🐝 seem to love it. 

6. Dandelions (Leontodon taraxacum): The bright yellow flowers make Dandelions a welcome harbinger of spring. These perennial plants have been used as an herb and medicinal plant since the time of the Roman Empire. The leaves and flowers are often used to make salads, beer, and wine. Mature leaves can be dried and used to make a mild tea. Roots can be used to make stronger tea, or dried and used for various medicinal purposes, including as a mild diuretic. Yet many gardeners prefer eliminating dandelions because of how aggressively they spread with the wind. Keeping dandelion seeds from germinating won't be enough to eliminate the plants. You can use herbicide to eliminate your dandelions, but the most effective and least harmful approach is to dig the flowers up from the roots. Removing dandelions by hand-pulling or hoeing is usually futile, unless done repeatedly over a long period of time, because of the deep tap root system of established plants. 

Six pesky weeds

1. Field bindweed  (Convolvulus arvensis) is considered one of the most problematic weeds in agricultural fields throughout temperate regions worldwide and the Bay Area is no exception. It is almost impossible to get rid of. Here’s the scary part, the root system of bindweed can reach depths of up to 20 feet. Worse still, bindweed is troublesome wherever there is a trellis or tomato cage since it is a fast growing weed that quickly gets out of control in such situations. It is especially bad news if you grow potatoes, beans, and tomatoes as it can harbour the viruses that cause potato X disease, tomato spotted wilt etc. Field bindweed spreads from both seed and extensive underground horizontal stems (rhizomes), so not only prevent flowers from forming but dig out the roots (easier said than done 🙄).

2. Morning Glory  (Ipomoea spp.) is closely related to bindweed and just as impossible to get rid of. Don’t be fooled by the multicoloured trumpet-shaped blooms, from violet or blue to pink and red, once it takes root it spreads like wildfire. Destroy seedlings while they are small, because once they have twined up stems they are difficult to control without injuring the crop. Seeds remain viable in the soil for long periods. Seeds of Ipomoea species contain many types of alkaloids, including some that are neurotoxins to humans and animals when consumed.

3. Crabgrass (Digitaria) is a weed almost everyone is familiar with. Two species are common in California—smooth crabgrass (Digitaria ischaemum), and large or hairy crabgrass (Digitaria sanguinalis). As annuals, they germinate, set seed, and die within one year. It spreads by seed and from rootings of the joints (culm nodes) that lie on the soil. Controlling crabgrass in soring itself before it has a chance to set seed is important because the seeds can remain viable for at least 3 years in the soil. Synthetic landscape fabrics covered with mulch will reduce crabgrass in shrub beds and bedding plants and around trees by blocking sunlight needed for its germination, establishment, and growth. However mulching is a double-edged sword. Organic mulches that have been on the soil for a while decomposing can provide an adequate growth medium for weeds to germinate and grow in. If crabgrass is germinating in the mulch, move it about with a rake to reduce seedling establishment. Hand pull escaped crabgrass plants before they set seed.

4. Stinging Nettle (Urtica dioica) is a fast-growing herbaceous perennial. The leaves and stems are covered with fine hairs, some of which have the troublesome habit of detaching and injecting a burning, stinging chemical when touched. This plant is best managed by hand pulling. As a perennial plant, stinging nettle may live for several years regrowing from rhizomes. Wear gloves to protect your hands from the stinging hairs on the plant stems. 

5. Common Mallow (Malva neglecta) is a fast-growing weed from the family Malvaceae, which includes a number of desirable plants, most notably cotton, hibiscus, and okra. One species of this family (Althaea officinalis) is actually the original ingredient to make marshmallows. Mallow only reproduces by seed with a tough seed coat that results in low germination each year, but a long viability of the seeds. If however the seed coat is nicked or otherwise altered to allow water in, seeds can germinate the same season they mature.  In such cases pull young plants before the roots go deep, this is best accomplished when the plant has four or fewer true leaves. After this the roots can spread up to 2 feet, making it impossible to remove even with garden tools.

6. Thistle (Cirsium vulgare) is a rhizomatous perennial with prickly spines and pinkish-purple flowers with a deep, vigorous taproot. It produces thistlelike flowers with sharp spines surrounding the base. Remove from the root as soon as it germinates.

References 

1. Weed specific information. (n.d.). UC David - Weed Research and Information Center. Retrieved August 8, 2024, from https://wric.ucdavis.edu/information/info_spec_weed.htm
2. Beaulieu, D. (2024, January 17). 42 Common Weeds in Lawns and Gardens: Identification & Control. The Spruce. Retrieved August 8, 2024, from https://www.thespruce.com/pictures-of-weeds-4069715