Everything You Need To Know About Grassy Weeds

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Grassy weeds are a common problem in lawns and gardens here in the Salt Lake City area. While these plants may look like regular grass, they can quickly become an issue for homeowners if they are not properly controlled and managed. Understanding more about these pesky plants is key to keeping your lawn looking its best, so let's dig in and learn all about grassy weeds!


What Are Grassy Weeds?

crabgrass bunch growth

Grassy weeds (sometimes called grass-like weeds) are invasive and unhealthy plants that grow where they are not wanted. In particular, your lawn can easily become the site of a grassy weed invasion without you even knowing it. This is due to the similarities between the healthy turfgrass that makes up a lawn and unhealthy grassy weeds that will steal nutrition away from the healthy grass.

Like all lawn weeds, grassy weeds tend to get first access to any nutrients and minerals in the soil, as well as any water or fertilizers you may apply throughout the year. Grassy weeds are more aggressive and have invasive roots that encroach on the root system of your lawn. Unfortunately, even grass types that are considered healthy and desirable in certain climates can behave as grassy weeds if they find a way into the wrong climate zone. If left untreated, your lawn will start to appear patchy, weak, and thin as grassy weeds outcompete your turfgrass for resources. Common grassy weeds you may see in Utah include annual bluegrass, crabgrass, goosegrass, creeping bentgrass, and more.

Identifying Grassy Weeds

What does Bluegrass look like

To understand why a grassy weed invasion is so bad for your lawn, you must first understand what grassy weeds look like. The close resemblance of grassy weeds to turfgrass is what makes these weeds so hard to spot in your lawn, which makes them even harder to control. Thankfully, there are some key differences you can look for that indicate whether you are seeing a grassy weed. As grassy weeds are essentially just different types of grass than the grass in your lawn, you can usually identify an invasion by looking for grass blades/leaves that are shaped differently than the rest of your grass. One of the telltale signs of a grassy weed invasion is patchy and uneven areas in your lawn. As a different and aggressive type of grass, grassy weeds grow at faster rates, and they often appear brighter or more green than your turfgrass. This is especially true if an invasion has already begun and your healthy grass starts to become thin and yellow.

Look For These In Your Lawn:

  • Taller growth than the surrounding grass
  • Quicker growth rate
  • Brighter, green leaf blades
  • Different leaf shapes (rolled, pointed, etc.)
  • Discolored or thin patches in lawn
  • Prominent seed heads
  • Shallow, invasive roots
  • Bunching or clumping growth pattern

Where Do Grassy Weeds Come From?

What does goosegrass look like

Most grassy weeds will have root systems that are much more complex, shallow, and invasive than the roots of turfgrass, which is how grassy weeds are able to overtake a lawn relatively easily. Depending on the species, grassy weeds produce rhizomes (under ground), stolons (above ground), or a combination of both in order to spread the invasion quickly. Many varieties even sprout new plants at the nodes that will take root all over your lawn. This allows them to spread quickly, and they typically like to hide in areas that don’t get mowed very often or get the most sunlight.

Unfortunately, the most common causes of grassy weeds are related to improper lawn care techniques. Grassy weeds seek out lawns that are already struggling because those lawns will be easier to invade and overtake. Excessive levels of nitrogen and moisture are prime real estate for grassy weeds, and these conditions can develop very easily if you are not careful. You are most likely to see grassy weeds if the following conditions and situations exist in your yard:

  • Shady spots in yard
  • Areas with poor drainage
  • Overly fertilized lawns/soil
  • Underneath trees & shrubs
  • Untended borders & beds
  • Generally struggling lawns

Life Cycle Of Grassy Weeds

crabgrass seedhead (2)

Annual grassy weeds are plants that complete their life cycle within one year. They tend to have a short germination period and can quickly invade a lawn, growing rapidly in the warm months before dying off in winter. Most annual grassy weeds produce seeds that are dispersed every season and remain dormant in the soil until the right conditions are present for germination. These plants tend to thrive in areas with ample sunlight, fertile soil, and plenty of water. Winter annuals will even go dormant in the cold months and attack your lawn as soon as spring arrives, well before your lawn even has a chance to get established.

  • These plants only survive for one season and do not have enough time to develop overly complex root systems. For this reason, seed dispersal is the main way annual grassy weeds spread.

Perennial grassy weeds, on the other hand, may live for two or more years, and they can often thrive throughout multiple seasons. While some perennials can survive unfavorable conditions, such as drought or freezing temperatures, others prosper under more favorable conditions with adequate sunlight and moisture. Perennial grassy weeds often reproduce by using underground root systems to spread from one area to another, sometimes over great distances! Surviving through multiple seasons means these weeds have more time to develop roots (even deeper taproots), tubers, and runners all across your lawn.

  • In addition to spreading through rhizomes and stolons, perennial grassy weeds can also produce seeds; however, this is usually a secondary method of reproduction. The strong, invasive roots of perennial grassy weeds are the real troublemakers!

How Can I prevent Grassy Weeds?

Holmes Lawn Care - Rated #1 in Utah

Removing mature grassy weeds can be challenging, mainly because it is hard to treat them without damaging your lawn. Pulling up or digging out grassy weeds is not always the best choice because small fragments of plant matter left in the soil can sprout new growth. Weed killers can be used, but they must be applied very carefully when dealing with grassy weeds. Non-selective weed killers (like glyphosate) work best on grassy weeds, but they can not differentiate between healthy and unhealthy vegetation. Accidentally applying non-selective weed killers to your lawn will cause your grass to die, leaving your lawn open for another weed invasion in the future.

Preventive lawn care is always the best choice for controlling grassy weeds. In the Salt Lake area, you can always call a professional like Holmes Lawn & Pest to take care of your grassy weed problem! We have all the experience needed to rid your lawn of these pesky weeds without damaging your grass. To prevent grassy weeds from ever taking hold in the first place keep the following tips in mind:

  • Aerate Compacted Soil - Aeration decompresses compacted soils, which allows your lawn to thrive and crowd out harmful weeds.
  • Fertilize Properly - Too much nitrogen in your lawn is a common cause of grassy weeds, which is why fertilizing properly is so important.
  • Water Deeply - The shallow roots of grassy weeds get first access to water, so longer, infrequent watering sessions give your lawn a chance to hydrate.
  • Mow High - Allowing your grass to grow slightly taller than normal can help crowd out any weed seedlings that try to emerge.
  • Use Mulch - Mulching your garden beds and soil can help to reduce the spread of grassy weeds by preventing them from emerging.
  • Apply Pre-Emergent - Pre-emergent is best applied in spring, while young seeds are still germinating. Call Holmes at (801) 616-5296 for professional weed control services in Utah!

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