You don’t need polluting chemicals to handle problem weeds
By Catriona Tudor Erler

                Weeds are flippantly defined as any plants growing where you don’t want them. While there is some truth to that definition, it is unhelpful to all gardeners who face dealing with true weeds: the aggressive plants that are adapted to a multitude of environments and that compete with the plants you really want for water, nutrients and light. As comic strip writer Brian Crane had the grandfather say in his “Pickles” strip, “If it’ll survive without being watered, fertilized, pruned, sprayed, staked, mulched, misted, dusted or wrapped, it’s a weed.”  While it’s impossible to completely eradicate weeds (the seeds are delivered by birds and animals, or float on the air to your garden plot from nearby properties), you can go a long way toward controlling them without using polluting chemicals. 
                Weeds are easiest to remove when they’re young and the roots aren’t well established. In garden beds, you can uproot them with a hoe, being careful not to disturb the roots of nearby plants. Hand dig well-established weeds. Here’s a case where procrastination will cost you dearly. If you wait until the plants have set seed, you’ll be faced with a larger weed problem next year.
                Mulch is probably a gardener’s best weapon against weeds in the beds. The covering over the ground prevents the seeds of many weeds from germinating, and the few that do overcome the mulch obstacle tend to be spindly and easy to pull. Organic materials, such as dried grass clippings, straw, shredded leaves, cocoa bean hulls, and shredded bark improve the soil while they keep weeds under control, but decorative rock, glass beads or marbles, and other similar materials also do the job and add an extra design feature to the garden. 
                If you’ve got a problem with weeds growing up between cracks in paving, consider vinegar as an environmentally safe remedy. A bottle of household vinegar has a 5-percent concentration, which researchers for the Agricultural Research Service in Beltsville, Md., found to be adequate to kill young weeds. Older, more established plants need a higher concentration, ideally about 20 percent.    
                In lawns, the most effective method of controlling weeds is to maintain a dense and vigorously growing turf cover. A weakened lawn, with or without bare patches, is the most common reason for increased weed presence. Killing the weeds without correcting the underlying problem will lead to unsatisfactory results. For example, a problem with knotweed is usually an indication of severe soil compaction. If you try to control the knotweed without correcting the problem, you still have a sparse grass cover and the area will again be invaded by weeds that grow in compacted soil.
                Often turf weeds can be controlled simply by altering the cultural practices to favor the grass plants rather than the weeds. Cultural controls may include raising (or lowering) the mowing height, changing the frequency of mowing, lengthening (or shortening) the period between irrigation, increasing (or decreasing) the application of fertilizer, or aerating the soil.
                Control any annual weeds that intrude in the grass simply by mowing before they set seed. The plant will die at the end of its growth cycle. Perennial plants are more of a problem. If you have them in small quantities, hand weed the lawn. Be sure and get the weeds out before they set seed and work to remove the weed’s entire root system. It’s easier to hand weed when the soil is moist and soft. Another option is to use a fertilizer in early spring that is mixed with a pre-emergent weed killer. Be aware, however, that this is a non-selective herbicide. It will kill grass seeds as well as weed seeds. 
                The other weapons in a lawnkeeper’s weed-control arsenal are broad leaf weed killers. Use these products with restraint. Many weed killers will lessen the vigor of grass roots, increasing the odds in favor of more weeds, and some will kill beneficial bacteria and earthworms in the soil. Some lawn fertilizers come with broadleaf weed killers as an added ingredient. They work if the conditions are perfect. Ideally, the leaves must be damp so the herbicide sticks to them, but then you don’t want rain for a specified length of time while the chemicals are being absorbed into the broad leaf plant’s system. You may find it more efficient and practical to spot spray the broad leaf weeds in your lawn with a specially-formulated herbicide.
                Weeds are a gardener’s bane, but many do have intrinsic value. Some are edible. Dandelions were introduced to North America by settlers because both the greens and flowers are good to eat. Purslane is a low-calorie, highly nutritious green that is thought to help lower blood pressure. It can be eaten raw in salads or lightly steamed. Orioles and goldfinches, two birds who consume many insect pests, use the silky seed pods of milkweed and thistles to line their nests, and Queen Anne’s lace is host to dozens of beneficial insects that eat unwanted aphids, caterpillars, and hover flies. So perhaps it is true that a weed is merely a plant growing in the wrong place.

Catriona Tudor Erler is a freelance garden writer and photographer who divides her time between Smith Mountain Lake and Charlottesville, Virginia. She is the author of  eight garden books including “Poolscaping: Gardening and Landscaping Around Your Swimming Pool and Spa,” “The Frugal Gardener: How to Have More Garden for Less Money,” and “Complete Home Landscaping.”