Is That Crabgrass? How To Identify This Tricky Weed

Crabgrass is the scourge of many a beautiful suburban lawn. This aggressive, fast-growing weed can quickly take over bare spots and sparse areas, forming dense mats that crowd out surrounding grass. Once established, crabgrass is notoriously difficult to control, constantly sending up new shoots and spreading via seeds and runners. That's why it's crucial for homeowners to learn how to identify crabgrass early, before it gets a foothold in the lawn.

We'll explore how its appearance changes based on growing conditions and compare it to other common lawn weeds. We'll also provide tips for detecting crabgrass before it transforms from a few stray sprouts into a full-blown infestation. Arm yourself with the knowledge below and you can catch this lawn invader right away, before it wreaks havoc on your turf!

When Does Crabgrass First Appear?

Crabgrass germinates when soil temperatures reach 55-60deg F, usually in early spring. The first seedlings will begin peeking through the soil as temperatures rise in late winter or early spring. At this early stage, crabgrass looks like light green corn plants emerging from the ground. The leaf blades are about 1/4 inch wide - noticeably thicker than typical lawn grass blades.

These early crabgrass sprouts will grow quickly in any bare, sparse spots around your yard that get full sun exposure. Crabgrass thrives best in thin areas of the lawn where there is little competition from existing grass and weeds. Sunny areas along driveways, walkways and flower beds are prime targets for pioneering crabgrass plants.

Ideal Conditions for Early Growth

Crabgrass needs several key conditions to germinate and establish itself:

• Warm soil temperatures above 55deg F
• Open, sunny areas with little competition
• Moisture - either from rain or irrigation
• Disturbed, bare soil that has been aerated or raked

If you notice unfamiliar grassy plants popping up in sunny, bare spots early in spring, chances are good it's young crabgrass. Keep an eye on these suspicious sprouts as the weather warms up.

How Does Mature Crabgrass Look?

As crabgrass matures, its appearance becomes more distinctive. The plant sends out shoots that root at the joints where they touch the ground. These new shoots branch out from the original stem, forming a low, dense mat of foliage. Mature crabgrass has a sprawling, tangled growth habit rather than growing in upright bunches.

The stems radiate out from the center of the plant, often leaving the middle exposed. Crabgrass leaves tend to be a medium to dark green color once established. The leaf blades are usually about 1/4 to 1/2 inch wide - significantly wider than common lawn grasses. As the mat-like clumps expand, they become obvious eyesores standing out from the surrounding lawn.

Spreading Habit

One key way to identify mature crabgrass is its spreading habit. The plant sends out runners called stolons that extend several feet from the original root system. Wherever a node on these stolons touches the ground, it can put down new roots. This is how crabgrass forms steadily expanding patches that merge into one another.

In addition, crabgrass continuously generates new shoots from the crown at the base of the plant. So mats get thicker and denser over time. All this branching and vining creates a visible patchwork of crabgrass through the lawn by midsummer.

Crabgrass Growth Habits and Patterns

One tricky thing about crabgrass is that its growth habit can vary quite a bit depending on growing conditions. Here are some patterns you may notice:

Upright Growth

When young crabgrass sprouts are competing with other plants and grasses, they will initially grow in a more upright, bushy form. The plant invests more energy in vertical growth in order to reach sunlight.

Sprawling and Spreading

Once established, crabgrass switches to a more sprawling, spreading habit. In bare soil and full sun, the stems branch out horizontally along the ground. This allows the plant to maximize exposure to sunlight.

The stems extend and creep along the ground until they encounter competition, forming an increasingly large mat.

Faster Growth After Mowing

You may notice clumps of crabgrass looking fuller and taller than the surrounding lawn grass right after mowing. That's because crabgrass can quickly regenerate new upright growth. So while mowing temporarily slows it down, it bounces back faster than slower-growing lawn grasses.

This difference in regrowth rate after mowing is a telltale sign of a crabgrass problem. The weed will stand out clearly against the trimmed lawn grass right after cutting the grass.

Crabgrass Color Variations

Young crabgrass starts off a light green when germinating and then typically turns a lush, darker green as it matures. However, the plant can take on some different colorations depending on growing conditions:

Blue-Green Hue

When growing in drier soils or stressed conditions, crabgrass will exhibit a blue-green hue. This is the plant's adaptation to harsher environments.

Reddish Tinge

Some crabgrass varieties have a faint reddish or purplish tinge to the stems and leaf blades. You may notice this more when plants are young or when cooler fall temperatures arrive.

So be aware crabgrass color can range from light green to blue-green. It likely won't be a rich dark green or have red/purplish shades like some ornamental grasses.

How To Distinguish Crabgrass From Other Lawn Weeds

Crabgrass shares some similarities with other common grassy lawn weeds. But there are a few key differences that can help confirm you're dealing with crabgrass:

Leaf Blade Width

Crabgrass blades are significantly wider than fine fescue and most ryegrass cultivars. Fescue will have very thin, almost thread-like blades under 1/16 inch wide. Crabgrass starts around 1/4 inch wide even as young plants.

Crabgrass foliage is also generally wider and coarser than common Bermuda grass. But it's a closer call, since Bermuda blades can get up to 1/8 inch wide in some varieties.

Growth Habit

Crabgrass tends to grow in prostrate, sprawling mats rather than compact upright clumps. Grass weeds like fescue, ryegrass and foxtail will stay in tighter bunches vs. spreading out.

Also look at the base of the plant - crabgrass stems branch out at ground level into a star-shape pattern. Grass weeds tend to have more upright, single stems.

Fast Germination

Crabgrass is one of the fastest-germinating summer weeds. It springs up earlier than other warm season grass weeds. If you see quick-growing, grassy plants in bare spots in early spring, suspect crabgrass.

Crabgrass also shoots up its seed stalks earlier than many summer weeds, allowing an extended period of seed production.

Crabgrass Versus Other Common Lawn Weeds

How does crabgrass stack up visually against other familiar weeds? Here are some key differences:

Dandelions

Dandelions emerge as a basal rosette of jagged, toothed leaves close to the ground. The leaves arehairless and smooth vs. crabgrass's rougher texture. Dandelions also have a single taproot vs. crabgrass's fibrous, branching roots.

Plantain

Plantain leaves are much more distinct with thick ribs and deep veins vs. crabgrass's smooth, flat blades. Plantain leaves emerge from the base in a rosette pattern. The seeds are very noticeable, while crabgrass seeds are not as evident.

Clover

Clover can resemble young crabgrass until it grows its signature triple leaflets. Clover has a vining, spreading habit similar to crabgrass. But clover displays rounded, smooth-edged leaflets on reddish stems - quite different from crabgrass foliage.

Goosegrass

Goosegrass is one weed that looks very similar to crabgrass when young. Look for the cottony-white center at the base of the plant as a key identifier. Mature goosegrass also tends to be slightly bluish-gray vs. crabgrass's darker green hue.

When To Be Concerned About a Possible Crabgrass Invasion

Here are some signs that warrant closer inspection for potential crabgrass:

• You see fast-growing, light green sprouts in thin, bare patches of lawn in early spring.
• An unfamiliar coarse, dark grass appears and spreads after summer rains.
• Sudden lush patches of grass grow faster after mowing compared to the lawn.
• Leaf blades seem wider than your lawn grass, with visible runners spreading out.
• Clumpy, sparse areas resist filling in despite fertilizer and overseeding.

Crabgrass thrives on neglected, thin spots in turf. So if certain areas resist improving or seem overrun by weeds despite your lawn care efforts, crabgrass may be the culprit.

Ideal Crabgrass Conditions

Be extra vigilant if your lawn has the ideal conditions for crabgrass:

• Sunny, southern exposure with no shade
• Sandy or loamy soil that drains quickly after watering
• Irregular mowing and fertilizing schedule
• History of crabgrass pressure and infestation
• Previous turf damage or bare patches from pet urine, digging, etc.

When these prime crabgrass-friendly factors exist, carefully inspect any new growth and don't wait to take action on possible crabgrass invaders.

How To Stop Crabgrass Before It Takes Over

Catching crabgrass early is the best defense. Here are proactive steps to stop crabgrass before your lawn is lost to this stubborn weed:

Pre-Emergent Herbicide

Applying pre-emergent crabgrass preventer in very early spring can stop seeds from germinating. This provides an effective chemical barrier against crabgrass

Timing is critical - apply before soil temperatures reach 55degF. This prevents the first flush of crabgrass seedlings.

Crowd It Out

Thicken thin areas of your lawn in fall and early spring with overseeding and fertilization. A lush, dense lawn leaves little room for crabgrass seedlings.

Mowing high (3-4") also encourages turfgrass to fill in bare spots before crabgrass invades.

Hand Pull

Manually removing young crabgrass plants is effective for light infestations. Use a weed popping tool to easily extract seedlings root and all.

Focus on catching the early, actively growing crabgrass plants before their growth explodes in summer.

Continual hand pulling is also required to keep stragglers from reinfesting the lawn all summer. So be diligent if using this control method.

With its remarkably fast growth rate andspreading habit, crabgrass can quickly get out of control during its peak season. That's why learning how to spot this lawn invader early is so important. Keep an eye out for crabgrass signs we covered like leaf blade width, spreading growth, and rapid regrowth after mowing.

Arm yourself with knowledge of ideal crabgrass conditions and vulnerabilities. Target thinly dispersed plants right away by hand pulling or using pre-emergent herbicide. Deny crabgrass the bare soil it needs by improving lawn density and health. With persistence and prevention, you can send crabgrass packing before it plagues your landscape!