The plant commonly called morning glory in a lawn context is field bindweed (Convolvulus arvensis). This perennial vine is one of the most difficult weeds to manage because of its aggressive, deep-reaching root system. Eliminating morning glory requires a strategic, long-term approach that attacks its extensive underground network rather than just the visible vines.
Understanding Its Invasive Nature
The reason morning glory is so difficult to eradicate lies beneath the soil surface, where it develops an extensive root structure. Vertical taproots can descend to depths of 20 to 30 feet, making physical removal nearly impossible. The plant also produces creeping lateral roots, or rhizomes, which can sprout new shoots many feet away from the original vine. This deep root system serves as a massive food reserve, allowing the plant to survive repeated surface treatments or mowing. If the above-ground foliage is removed, the plant simply draws on these reserves to quickly regenerate new shoots. Furthermore, morning glory reproduces by both root fragments and by seed, with the seeds remaining viable in the soil for up to 50 years.
Non-Chemical Removal Methods
For small, isolated patches, manual removal can be effective, though it demands extreme diligence. Hand digging must be done carefully to remove as much of the root system as possible, which requires digging down at least 10 to 12 inches. Breaking the brittle roots is counterproductive, as even small fragments can regenerate into new, independent plants.
A more practical cultural control method involves strengthening the turfgrass surrounding the weed to suppress its growth. Maintaining a dense, healthy lawn by raising the mower blade limits the amount of sunlight that reaches the low-growing morning glory vines. The shade provided by taller turfgrass helps to starve the morning glory of the energy it needs to thrive.
Smothering is a highly effective non-chemical option but is generally impractical within an actively used lawn area. This technique involves covering the affected area with thick, opaque material like heavy-duty landscape fabric or layered cardboard for at least one to two growing seasons. This prolonged light exclusion depletes the root reserves.
Selective Herbicide Application
A systemic, selective herbicide is often the most efficient way to achieve long-term control within a lawn due to the plant’s deep root system. Selective herbicides are formulated to target broadleaf weeds like morning glory without causing damage to the surrounding turfgrass. Effective products typically contain a combination of active ingredients, such as 2,4-D, dicamba, and triclopyr.
The timing of the application is the most crucial factor for success. The herbicide must be applied when the plant is actively transporting nutrients down to its roots, a process called translocation. This movement is strongest in the late summer or early fall, when the plant shifts energy to storing food for winter survival. Applying the herbicide during this period ensures the poison reaches and kills the deep root system.
To maximize absorption, avoid mowing the area for several days before and after treatment to ensure maximum leaf surface area is available. For heavy infestations, a broadcast application may be necessary, but spot treating is preferred for scattered weeds to limit chemical use. This involves directly spraying the individual morning glory vines until the leaves are thoroughly wet.
Follow-up applications are nearly always required for complete control, as a single treatment rarely eliminates the entire root system. Reapplication intervals vary by product, but a second treatment may be needed 10 to 30 days after the initial spray, or in the following season. Always consult the product label for specific mixing instructions, application rates, and safety precautions.
Maintaining a Weed-Free Lawn
After initial control, the focus shifts to long-term maintenance and prevention. The most effective defense against morning glory is a thick, healthy stand of turfgrass. Overseeding thin areas and following proper fertilization and irrigation schedules creates a dense canopy that shades the soil, making it difficult for new morning glory seedlings to establish.
Consistent monitoring is necessary because the deep seed bank means new plants can germinate for years. Immediately remove any new seedlings as soon as they appear, ideally before they develop the deep taproot that makes mature plants so difficult to manage. Seedlings are much easier to pull completely than mature plants.
Expect to perform follow-up spot treatments with selective herbicides in subsequent years, typically in the late summer or fall. This vigilance is necessary to neutralize any new shoots that emerge from remaining root fragments or dormant seeds. A persistent, multi-year management plan is the only reliable way to ensure this aggressive weed does not regain a foothold in your lawn.