How to Prevent & Kill Weeds

Weeds can be problematic for any homeowner, especially since there are thousands of weed species in existence and about 25-30 of them can be found even in well-maintained turf. As you survey your lawn and garden, look for dandelions, milkweed, chickweed, crabgrass and others. Not all weeds are unattractive, but many can become an invasive and unwanted presence on your property. Unfortunately weeds spread easily; they can be transported by humans, animals, insects and even water. If left unchecked, weeds can deprive your grass and your flowers and plants in your garden of needed water, light and soil nutrients.

Luckily, there are measures you can take to reduce, eliminate and, most importantly, prevent the annoying weeds that threaten the health of your lawn and garden. Follow these steps to get started.

Prevent Weeds Before They Grow

Stop weeds before they start by changing your gardening practices slightly. A variety of organic and non-organic methods exist for preventing weeds before they start to grow.

Step 1: Use ”Weed-Free” Soil

An important step in weed prevention is to ensure the topsoil and other covers you are using are weed-free. If the package does not specifically state that the product is ”weed free,” you could be unknowingly putting weeds into your garden. If you are planning a new garden or have a weed-plagued garden, removing old topsoil and replacing it with weed-free soil is a great way to get a fresh start. Throw out old soil to prevent weed seeds from propagating.

Step 2: Mulch

Family spreading mulch on garden bed.
Mulching is a great project young kids can participate in.

Mulching is a useful aid in controlling weeds, especially the annual type. Mulching also provides the benefits of conserving soil moisture, keeping soil at a more uniform temperature, preventing erosion and creating a more attractive garden appearance. A thick layer of organic mulch such as grass clippings, leaves, garden bark or similar materials is the best choice.

An effective, environmentally friendly way to supplement mulching is to spread a 6” layer of shredded newspaper with your regular mulch along plant beds and walkways. Weeds can’t germinate in the dark, so the paper helps keep them from sprouting. Each year, when you add new mulch, check the newspaper and add more layers where needed.

Step 3: Use Pre-Emergent Herbicides

Man shaking Prepemergent Herbicide on freshly mulched garden bed
Pre-emergent means no weeding for 2-3 months.

Pre-emergent herbicide controls weeds or weed seeds before they can ”emerge” or germinate. It does not kill existing weeds. By using a pre-emergent herbicide, you can effectively prevent weeds for up to three months. Sprinkle by hand or use a garden hose attachment to spray on the soil surface of garden beds or on top of mulch. Water afterward. Some types work best when added into the top 2-3” of the soil while others should be applied directly to topsoil. Follow package instructions.

Helpful Tip

Herbicide can be selective or non-selective. Selective herbicide only kills weeds; non-selective herbicide can kill any plant it comes into contact with. When using non-selective herbicide, take care not to damage wanted garden plants.

Step 4: Water Sparingly

Overwatering can lead to unwanted weed growth and can actually harm your plants. To control the amount of water you use, install a seeper hose or a regular garden hose altered to produce a slow stream of water. You can also use cans for efficient water distribution. Punch holes in the bottoms of juice or coffee cans with a hammer and nail. Push the cans 6-12” into the soil right side up and fill them with water. The water will gradually seep from the bottom into the soil directly surrounding plant roots. This method will greatly reduce evaporation and unnecessary wetting of surrounding soil.

Step 5: Use Weed Prevention Mixes

Take advantage of the many weed prevention mixes available. Usually consisting of a combination of fertilizers and weed inhibitors, mixes can safely reduce weeds from gardens without harming other established plants. Look for products that include corn gluten meal, a by-product of cornstarch that prevents weeds while adding the natural fertilizer nitrogen to the soil.

Step 6: Get into Good Mowing Habits

Annoying weeds and grasses can be as troublesome on the lawn as in the garden. Mow regularly with sharp, clean blades. Cut your lawn shorter in the spring but avoid cutting it too short. Fertilize with a high-quality organic fertilizer, water regularly, and reseed sparse areas in the spring and fall.

Kill Weeds

If your garden has an abundance of flowers, but they’re all dandelions, you probably want to do something about existing weeds. There are really only two methods of doing this: pulling or tilling weeds to destroy them, or killing them with chemicals.

Step 1: Pull Weeds

The classic method of weed elimination is to pull weeds by hand from the ground. The only way to ensure they won’t come back is to remove the entire root system. You can do this by pulling firmly by hand, using a shovel or weeding tool or by using a power tiller if the soil is compacted. Digging, chopping and turning the soil can be effective if you are trying to eliminate weeds that typically grow from seed and have a single clump root system. To make the job easier, turn soil immediately after a rain or after watering your garden. Spot check your garden once a week to keep weeds from coming back.

Be aware; pulling weeds will not guarantee a lasting solution, particularly with perennial weeds. Whereas annuals are produced by seed only and live for a single season, perennials can reproduce by seed or by vegetative means, such as rooting, and will continue to thrive as long as conditions permit. Perennial seeds can lie in soil dormant for as long as seven years waiting for the right conditions to germinate. Whenever possible, perennial weed seedlings and grown plants should be dug and discarded prior to using any power tillers. This is because power tillers chop up the perennial’s roots and create dozens of ‘root cuttings’ which will quickly grow into new weeds.

Step 2: Use Post-Emergent Herbicides (Weed Killers)

A post-emergent herbicide works on weeds that have already begun to grow. They kill existing weeds but won’t prevent new ones. They are particularly useful on annual types of weeds. When using post-emergent herbicides, take care not to damage wanted plants. If you spray an herbicide with a garden-hose attachment, wait for a calm day with little or no wind to prevent the chemical from spreading to adjoining flower patches and harming them. Wait 72 hours for the weed’s root systems to absorb the chemical before tilling. If you mow weekly, spray in the middle of that cycle so that the killer can sink into the weeds and do its work undisturbed. Avoid spraying herbicides on a newly seeded lawn or garden.

Safety Alert!

Many post-emergent herbicides are highly toxic. Purchase only as much as you need and wear protective clothing and garden gloves. Dispose of herbicides according to instructions.

Congratulations! You’ve made your garden more attractive by preventing and eliminating weeds.

Prevent Weeds: Project Shopping List

Here’s what you’ll need to complete this project successfully.

Kill Weeds: Project Shopping List

Here’s what you’ll need to complete this project successfully.