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what causes weeds to grow

What causes weeds to grow

Eradication of weeds is not a realistic or necessary goal. Some weeds develop even in a well-cared-for lawn. Healthy grass in fertile soil discourages weed growth. Hand weeding throughout the year may be all that is necessary when good management techniques are practiced. Hand weeding is especially useful to prevent the spread of sedges, dandelion, spurge, creeping wood sorrel, dallies-grass and Bermuda grass. Remove the weeds when they are young before they spread, grow seed or develop rhizomes. A dandelion fork or fishtail weeder is useful for removing weeds with a thick taproot.

Bermuda grass and dallis-grass are perennial grass weeds which establish themselves in lawns that are mowed too closely, are overwatered, have compacted soil or are subject to excess heat and sun. Spurge grasses, knotweed, burclover and black medic are broadleaf weeds that grow in lawns with low nitrogen fertility, compacted soil or are closely mowed and have open areas. Annual and perennial sedges become established in lawns that are overwatered and have poor drainage. Excess sun and heat as well as nearby infestations also cause sedge growth.

Annual grassy weeds such as bluegrass, crabgrass and goose grass grow, produce seed and die within one season. They return the following year if this cycle is not interrupted. Grassy weed seeds fall from the plant in autumn and germinate in spring when the soil temperature is between 55 and 60 degrees Fahrenheit. Conditions that cause the growth of annual grassy weeds are overwatering or light, frequent watering, a mower blade set too low or compacted soil. Grassy weeds take hold in lawns that are mowed to a height of less than 2 inches.

You can reduce weed growth in lawns significantly by following good management practices and understanding weed growth patterns. Improper fertilization, irrigation or mowing practices make it easy for weeds to invade even an established lawn. Identify the type of weeds plaguing your yard before beginning a control program.


Proper mowing, irrigation and fertilization practices prevent many weed problems. Mow every three to five days during growth periods to keep the lawn at a height of 2 ½ to 3 inches during the summer months. Leave clippings on the grass after mowing. Grass clippings provide about 20 percent of the fertilization needs of most grass types. Fertilizer needs vary according to grass species, but nitrogen is the nutrient most needed by all grass types. Organic compost fertilizers are applied once or twice yearly because they release nutrients slowly into the soil. Irrigate when the top 2 inches have dried out — or two to three times per week. Deep, infrequent watering discourages weed growth.

Perennial Grasses and Broadleaf Weeds

What causes weeds to grow

Mow higher. Raise your mowing height. Although many homeowners love the look of a closely cropped lawn, mowing too low can lead to a thin turf structure and cause weeds to creep in seemingly overnight.

Wet/soaked portions of the lawn

Areas where the lawn meets concrete (e.g. along driveway and sidewalk edges)

Anywhere compacted soil can be found

Questions about our environmentally responsible weed control treatments? Worried about areas in your lawn that may be vulnerable to weed attack? Contact your local Weed Man!

Thinning areas of the lawn

Fertilize regularly. A thick, healthy lawn is the absolute best defense against unwanted weeds. This is because a dense turf structure crowds out additional growth, making it difficult for weeds to sprout.

Be careful not to over water. Loose, saturated soil can be a breeding ground for weeds. If you’ve seen regular rainfall in your neighborhood, supplemental watering may not be needed.

But don’t fret – a lush, uniform lawn structure isn’t a suburban legend. Homeowners can keep weeds at bay and enjoy a pristine yard by following the tips below:

What causes weeds to grow

The first thing to remember is that a lawn is a living breathing organism. Just like our bodies, there are minimums that we need to provide ourselves with in order to remain in good health and promote a long life. Your lawn is no different. It needs the right amount of consistent water, good quality nutrients (AKA food and vitamins), proper and regular maintenance, attention to stress reduction, sunlight and of course protection from unwanted invaders.

So, in conclusion, the presence of weeds or moss in your lawn is a sign of the health of that environment. When your lawn is watered properly, kept mowed to 2 ½ – 3” in length, fertilized, the soil loosened (with a Core Aeration every year), the pH balanced (with a Calcitic Lime application), Seeded (to increase the amount of grass in the lawn) and has lots of sunlight it will become healthier and stronger. Similar to when we start to take better care of our bodies by eating right and exercising regularly, which does take some time, we are less likely to get sick.

Food is next, all living things love to eat, I know I do, I’m sure that you do too and your lawn is no different! In fact, there are a total of 18 nutrients needed in order to grow correctly, but only three of them — nitrogen, phosphorus and potassium — are used in quantities that might require supplementation. Low nitrogen in your lawn can contribute to the weed population as weeds are able to grow in areas that healthy plants cannot. Making sure that you (or the professionals here at Nutri-Lawn Vancouver) are putting down a high quality fertilizer with the proper amounts nutrients at the proper times of the year as your lawn’s needs will change with the weather.