The question of whether to pull weeds before mowing is a common dilemma. Strategically removing weeds before you mow is often the most beneficial approach, as mowing first can inadvertently turn your lawnmower into a tool for weed propagation. This decision depends on the type of weed and understanding the mechanical consequences of the mower blade.
Immediate Consequences of Mowing Weeds
Mowing weeds that have gone to seed can rapidly worsen an infestation by using the mower as a broadcast spreader. The high-speed rotation of the blades picks up mature seed heads, such as dandelions in their “puffball” stage, and forcefully distributes the seeds across the lawn. This mechanical dispersal leads to new weed germination in previously unaffected zones.
The mower also poses a risk to weeds that reproduce asexually through specialized stems. Weeds like creeping Charlie or crabgrass spread using stolons (above-ground runners) or rhizomes (underground stems). Chopping these runners can break them into smaller fragments, and each fragment may root and establish a new plant. This fragmentation essentially clones the weed, turning one parent plant into multiple problems.
Cutting the top growth of perennial weeds triggers a defensive response that encourages aggressive regrowth. While mowing temporarily suppresses shoot growth, the plant draws on stored food reserves in its roots to produce new stems. This response leads to a denser, lower-growing plant that is harder to spot and remove later, as the plant adapts to frequent cutting.
The Role of Weed Type in Decision Making
The necessity of pre-mowing removal depends heavily on the weed’s reproductive strategy. Tall, seeding weeds, such as thistles or dandelions that have matured past the flowering stage, represent the highest risk. These weeds must be removed entirely before mowing to ensure their seeds are not scattered across the turf. Quick removal prevents the widespread introduction of new weed seeds into the soil.
Creeping weeds, including clover and ground ivy, are generally low-growing, meaning the mower may not cut them significantly. Although pulling is the ideal solution to remove the entire stolon or rhizome network, these weeds are less catastrophic to mow than seeding varieties. However, running the mower over them still risks fragmenting their runners, enabling them to spread vegetatively across the lawn.
Taproot weeds, including common lawn invaders like dock and plantain, are best addressed before mowing. These plants feature a single, deep root that allows them to regenerate even if the top growth is severed. Mowing simply removes the leaves, which quickly grow back, while the root remains intact. Removing the entire taproot is the only way to eliminate the plant permanently, making pre-pulling the appropriate strategy.
Optimal Strategy for Manual Weed Removal
Effective manual weed removal begins with proper soil preparation. Pulling weeds is easier and more effective when the soil is damp, such as after rain or thorough watering. Moist soil reduces friction around the root, allowing the full taproot to be removed intact without breaking. This prevents the weed from regenerating from a remaining root fragment.
To ensure complete removal, use a specialized tool like a dandelion weeder or a narrow trowel to loosen the soil around the weed’s crown. The goal is to extract the plant with minimal disruption to the surrounding turf. For taproot weeds, a slight twisting motion while pulling helps the entire root slide out, preventing it from snapping off beneath the surface.
Once the weed is pulled, a small hole or divot remains in the lawn that must be addressed immediately. These bare patches are prime locations for new weed seeds to germinate because they lack competition from established turf. To prevent this, gently fill the depression with topsoil or a soil-compost mix, then lightly tamp it down.
The final step involves overseeding the repaired spot with grass seed that matches the surrounding lawn. Applying seed to the bare soil ensures the desired turf species quickly colonizes the area before new weed seeds can take hold. Maintaining consistent moisture in the patched area encourages rapid germination and establishment of the new grass.