Some weeds may harbor diseases, be poisonous, or cause allergic reactions to humans and animals. Left unattended, weeds can become invasive. But weeds aren't all lacking in advantages. Queen Anne's Lace, for example, attracts wasps that feed on aphids. Weeds also add organic matter to the soil, cover bare soil to prevent erosion, and are a source of medicine and food. Their presence can even tell you things about the condition of your soil.

Determining whether or not a plant is a weed is subjective. You may like having dame's rockets growing along your fence, but your neighbor may not share this fondness. For simplicity's sake, let's say that a weed is a plant that is growing out of place -- a plant that is interfering with the crops or flowers you wish to grow. With this in mind, let's explore effective ways to control them so that they don't absorb all the nutrients, light, air and space that are needed for your desirable plants to flourish.

Fall Dandelion or August Flower

Illustration from Farm Weeds of Canada (Classic Reprint Series)

Identifying Weeds

Finding the best method for controlling weeds depends on the type of weed you are dealing with. In our agrarian past, people could readily identify weeds by name, but this is no longer so. A good illustrated weed identification guide is crucial in your war against weeds. By knowing a plant's name, you can search for information on how to control it.

Annual weeds, those plants that live and die in one single season, reproduce by their seed. Planning your attack before seeds set will help in your battle to get rid of them. Shepherd's purse, stinkweed and ragweed are annual weeds.

Shepherd's Purse

Illustration from Farm Weeds of Canada (Classic Reprint Series)

Biennial weeds are those plants that complete their growth cycle in two years. Seeds are produced in the second year. Wild lettuce and evening primroses are just two examples of biennial weeds.

White Evening Primrose

Illustration from Farm Weeds of Canada (Classic Reprint Series)

Perennial weeds, those plants that live at least three years, can propagate by their root systems, rhizomes (underground stems), as well as their seed. Examples of perennial weeds include quack grass, dandelions and poison ivy. These can be quite tenacious.

Couch Quack or Scutch Grass

Illustration from Farm Weeds of Canada (Classic Reprint Series)

Establishing a Weed Control Plan

Since it is neither possible nor recommended to eliminate all weeds, a practical approach is to establish your own personal tolerance guidelines. What weeds are most annoying to you? Is a lawn free of dandelions more important than an ornamental garden free of wild yarrow? Can you sacrifice a spot in your yard to let evening primroses bloom? These are decisions that you alone can make.

Unfortunately, you can't get away with not weeding at all. Municipal by-laws (or local weed control ordinances) dictate the eradication of all noxious weeds. Weeds are deemed noxious when they have the potential to create fire or health hazards, reduce crop yields, invite pests, and spread crop diseases. Ragweed, poison ivy and loosestrife are considered noxious weeds, but your own municipality may have a different list. Consult your local municipality or extension service for specific weeds ruled as noxious in your area.

On the plus side, routine weeding keeps you informed about the state of your garden. It is with regular visits to your garden that you will be able to identify problems. Early detection of pest or disease problems gives you time to treat them before they get out of hand.

Weeds on Lawns

Weeds on lawns are good indicators that the soil is poor or overfertilized. Too much fertilizer harms the soil, which weakens the grass, which then gives way to weeds more readily. A steadfast lawn-maintenance program that includes removing thatch, aerating, top dressing with slow-releasing, long-lasting organic amendments, reseeding and frequent mowing (at the recommended height) can prevent weeds from invading your lawn.

If you have contracted the services of a lawn-maintenance company, ensure they are using herbicide-free products. Repeated chemical treatments have long-term harmful effects on all living creatures. Overuse of herbicides not only renders the soil infertile and kills other things besides unwanted weeds, but overexposure can lead to allergies and a host of other physiological problems.

Solarization and Presprouting

Solarizing and presprouting are two often overlooked ways to suppress weeds.

The idea behind solarization is that by covering an area with clear plastic sheeting for several weeks, the heat of the sun will raise the soil's temperature enough to kill weeds -- seeds and all. Although effective for controlling persistent weeds, solarization can take a season or two before you see any results. If you can't afford to wait that long, or the area in question doesn't receive a lot of sun, presprouting may be a better alternative.

To presprout weeds, prepare the area before setting any plants. Remove as many weeds as you can, including their roots and shoots. Add your organic amendments, such as compost, rake smooth, then water. (Note: If you are using manure as an amendment, make sure it has been sterilized. This ensures that weed seeds have been killed.)

Keep the soil moist until the area is covered with 2" high weed seedlings. As done earlier, pull out as many roots as you can, then use a hoe to slice the remaining weeds just below the surface. The effort taken early in the season will pay off when you see fewer weeds emerge.

Using Mulch

In garden beds, the use of organic mulches and landscape fabric prevents weeds from germinating. The lack of light causes weed plants to die, and those that do make it through can easily be pulled out.

Apply mulches in early spring ? after tilling and adding compost. Add mulch to pathways and any garden areas that will be planted at a later date. To avoid fungus diseases, such as root rot and damping off, keep organic mulches from seedlings until they are several inches tall. Top up throughout the season, then rake back in the fall to prevent mouse damage to plants.

Other Controls

Cover crops and ground covers, such as clover and periwinkle, offer other courses of action to help prevent weeds. They grow so quickly that weeds can't compete with them. Cover crops also enrich the soil.

Although prevention takes care of many weed problems, it does not take care of all of them. The key to keeping weeds under control is to remove them before they mature and set seed. Early meticulous weeding reduces the number of future weeds. Diligent weeding after transplanting or seeding and until crop and ornamental plants are well established will ease the burden later in the season. However, some weed seeds can remain dormant for quite some time; so no matter how attentive you are, you can expect the errant weed to spring up now and again.

Weeds that are growing close to plants and between plants can be pulled by hand. Grasp the weed at soil level with your thumb and forefinger, twist up and pull the weed out. Try to get the whole plant out, including the root; if parts of roots are left, the plant can and will regrow. Make sure to clean up the debris to prevent weeds from reestablishing themselves. You can compost pulled weeds as long as they have not set seed and as long as they are dead. Let pulled weeds wither and die in the sun to make them compostable.

For larger garden patches and vigorous weeds, a choice of dedicated hand tools makes weeding less of a chore.

Tools for Weeding

• Hoe. Used for slicing young weeds just below the soil. Available in many shapes and sizes, and for various tasks. If you get just one, select a long-handled multi-purpose draw hoe. Oscillating and collinear hoes cut small weeds with minimal soil disturbance. A loop hoe works well in congested areas.
• Digging Fork. For loosening the roots of weeds. Good for removing perennial roots and rhizomes.
• Spade. Can be useful for severing tough weeds.
• Weed Knife. A knife with a serrated edge is good for grubbing out weeds.
• Mattock. Good for chopping tough, overgrown weeds. Use the forked end to uproot persistent weeds.
• Trowel/Hand Fork. For loosening and digging out roots in tight spaces.
• Dandelion Weeder. Not just for dandelions. This tool is handy for removing long-rooted weeds from lawns and gardens.
• Crack Weeder. Solves the problem of removing undesired plants from the cracks of patios and walkways.
• Scythe. Helps to keep marginal areas of a property free of weeds.
• Weed Torch. Used to get weeds where other tools do not work. Propane gas flame shrivels foliage and causes the root to atrophy.
• Water. Roots are easier to remove when the soil is moist.
• Leather Gloves. Wear gloves not only to help keep hands clean, but to protect your hands from poison ivy, stinging nettle and thorny plants.
• Bucket. Either for toting your hand tools or for collecting weed debris.

Grandma's Recipes

Tried hoeing and hand pulling, but weeds are still winning? Before you reach for the commercial herbicides, try one of these old-fashioned ways to deal with weeds.

• Spot spray weeds in cracks with isopropyl alcohol or vinegar on a sunny day to kill them.
• Sprinkle salt over new weeds between cracks in patios and walkways.
• To spot treat crabgrass, use hydrogen peroxide diluted to 3 percent.
• Ground up sunflower hulls dropped into the cracks of sidewalks will prevent weeds from sprouting.
• To prevent weed grasses on lawns, spread corn glutten (cornmeal also works) on the problem area. Corn glutten will inhibit germination of weeds, add nitrogen and get rid of cutworms (they can’t metabolize the stuff).
• In the fall, combine cabbage leaves in a blender with some water. Pour the resulting mush over cracks in walkways and patio stones. Cabbage contains thiocyanate, a toxic chemical to newly germinating plants, especially those with small seeds.
• For best results, pull weeds the week before the New Moon.

Dandelion Destroyer

A lawn or yard thickly studded with dandelions presents a discouraging prospect at any time, but particularly when the owner considers digging them out. However, to a certain extent, the spread of the weeds can be controlled by preventing the blossoms from going to seed. The implement shown in the drawing, when pulled across a dandelion-infested lawn before the blossoms ripen, pulls of the flower heads, and thus effectively prevents self-seeding. A 12 by 16-in. piece of heavy galvanized iron, bent as shown, is toothed on one edge, the teeth being 1 in. apart and 1 in. deep. A piece of iron bar is riveted to the sheet iron so that it can be fastened to a handle and used in the same manner as a rake. (excerpt from Boy Mechanic, Book IV)

Further Reading

• All About Weeds, Edwin Rollin Spencer.
• Chemical-Free Yard & Garden, published by Rodale Press.
• Common Weeds of the United States, United States Agricultural Research Service.
• Controlling Garden Weeds, Barbara Pleasant.
• Dead Daisies Make Me Crazy, by Lorren Nancarrow & Janet Hogan Taylor.
• Farm Weeds of Canada, published by Lee Valley Tools Ltd.
• How to Grow Vegetables & Fruits by the Organic Method, edited by J.I. Rodale.
• Old Man's Garden, published by Lee Valley Tools Ltd.
• The Gardeners Kalendar, published by Lee Valley Tools Ltd.
• The Gardener's Weed Book, Barbara Pleasant et. al.
• The Garden Primer, Barbara Damrosch.
• Weeds of the Northern United States & Canada: A Guide for Identification, by France Royer and Richard Dickinson.