The Life Cycle of Weeds

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Nov 16, 2019

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Everything has a life cycle, even weeds. You know, all that circle of life and Hakuna Matata stuff Disney taught us all those years ago?

To control weeds properly, you must understand their life cycle. Understanding this can help you figure out why no matter how many times you pull that weed, it just comes back, or why a weed dies off in the winter just to return the following spring, or how one weed practically made 1,000 clones of itself and overtook your landscaping.

Here’s everything you need to know about the life cycle of weeds and how it affects the way you treat them.

Types of Weeds and Their Life Cycles

The Life Cycle of Weeds 1

In the wild world of weeds, there are various types, much like any other plant.

In some cases, they thrive in the fall and winter and die off in the spring and summer. Some prefer the warmer weather and grow through spring and summer but die in the fall or early winter. Others are more stubborn and take two full years to complete a life cycle or come back year after year.

Let’s look at the main types of weeds and their typical life cycles.

Summer Annuals

Everyone looks forward to a few things when summertime rolls around: warmer weather, the public pool opening, hitting the beach, summer vacation, and weed control. OK, we slipped that last one in on you.

Sure, no one enjoys summer weed control, but it is just a part of life with a yard. The weeds you will find this time of year are summer annuals. Their life cycle starts with germination around the time soils warm up in the spring to emergence in the early summer to death in the fall – generally after the first frost.

These weeds are most common in yards with cool-season grasses like Kentucky bluegrass and perennial ryegrass because they thrive in the heat while the cool-season grasses struggle with it.

Some of the most common summer-loving weeds are:

  • Crabgrass
  • Knotweed
  • Prostrate Spurge

Winter Annuals

About the same time we send our kiddos to school for their minds to germinate, winter annual weeds are doing germination of their own in your soil. In the late summer to early fall, these weeds start forming beneath the surface and emerge in the late fall or early winter.

These weeds thrive through the cool winter months and into the spring. They meet their demise once the warmer weather rolls in around late spring or early summer.

If you have warm-season grasses like Bermuda, St. Augustine, Bahia or others, you need to be extra diligent in seeking out these weeds. They can quickly overtake your lawn as it goes dormant in the winter and potentially leave you with big problems the following summer.

Some of the more common winter annuals include:

  • Shepherd’s Purse
  • Common Chickweed
  • Yellow Rocket
  • Annual Bluegrass

Biennial Weeds

As the name implies, biennial weeds are unique because they live for two years and go through two distinct phases.

In its initial year, a biennial weed will germinate and grow, but it does so without flowering. Instead, it forms a rosette, a plant with no central stalk and leaves that emerge near the soil.

Year No. 2 is when the bigger problems arise, as the biennial weed will kick off its second phase by growing a flowering stalk. A flowering stalk means one thing: seeds.

After the biennial weed flowers and seeds, it dies. While it may be dead, it left behind a legacy of seeds that can result in many more like it in the coming years.

Some common biennial weeds include:

  • Primrose
  • Burdock
  • Common Mullein
  • Moth Mullein

Perennial Weeds

Perennial weeds are among the most aggravating of invasive species, as they remain year after year without ever fully dying without outside intervention. Depending on the type of perennial you’re dealing with, they can also spread like.. well.. wild weeds.

There are two main types of perennials. Let’s dive into each and learn how to identify them.

Simple Perennials

Sometimes referred to as solitary perennials, simple perennials grow individually with one root system per plant. You may find them in large groups because of the way they seed, but if you pull one plant you will find an independent root system.

These root systems, called taproots, grow downward vertically and can become very large over the years.

Some examples of common simple perennials you may find in your yard include:

  • Curly Dock
  • Plantains
  • Dandelions
Spreading Perennials

Have you ever had a weed that spread and took over your landscaping before you knew it? There is a good chance you were dealing with a spreading perennial.

These perennial weeds are the ultimate reproducers because they not only drop seeds, but they also send out horizontal stems, often called rhizomes (underground) or stolons (on the surface). From these horizontal stems, new weeds emerge and continue the spreading process until they eventually take over.

Some spreading perennials you may find in your yard include:

  • Yellow Nutsedge
  • Ground Ivy
  • Hedge Bindweed
  • White Clover

Ending the Life Cycle

The Life Cycle of Weeds 2

Great, you now have a firm understanding of how the various types of weeds go through their life cycles, but you need to know how to stop them. There are two main methods in stopping weeds, and the one that best suits you depends on what point in the life cycle you catch the weeds in, pre-emergent or post-emergent.

Post-emergent

Unless you are the Superman of weeds with X-ray vision, the first time you catch a weed cropping up, it will generally be post-emergent. This is after the weed has popped through the soil and is on its way to becoming a full-size nutrient hog.

At this point, you need post-emergent weed control chemicals to kill off these weeds before they have a chance to drop seeds or spread via horizontal stems. When performed correctly, post-emergent weed control sets you up nicely to prevent these weeds before they even emerge next year.

And that brings us to our next life-cycle-stopping process.

Pre-emergent

Get ‘em when they’re young, and they can never be an issue. That’s the rationale behind pre-emergent weed control.

When performed at the right time, pre-emergent weed control allows the seed to germinate but never break the surface of the soil. Knowing the best time to apply pre-emergent weed control is critical, so you first need to scout your yard for weeds regularly so you know if you’re dealing with winter or summer annuals.

If you’re dealing with biennials or perennials, make sure to kill them with post-emergent chemicals before applying your pre-emergent weed control. This way, you know no new seeds will find their way to the ground and sprout after the pre-emergent treatment wears away.