The question of whether Morning Glory plants are invasive is complex because the common name refers to multiple species with vastly different growth habits. These twining vines are found in gardens and natural areas, and their aggressive climbing nature often leads to concern. The level of threat depends entirely on the specific plant species, which determines the necessary management approach. The plants grouped under this term can be either fleeting annual ornamentals or highly persistent, deeply rooted perennial weeds.
Clarifying the Identity of Morning Glory
The plants most frequently labeled “Morning Glory” belong to two main groups: the annual ornamental vines in the genus Ipomoea and the perennial, aggressive bindweeds in the genera Convolvulus and Calystegia. Ornamental varieties, such as Ipomoea purpurea, are cultivated as annuals, meaning they complete their life cycle in a single growing season and are killed by frost. While they grow quickly and can self-seed aggressively, they lack the deep, perennial root structures that define true invasive weeds.
The species causing the most difficulty are the perennial bindweeds, often called Field Bindweed (Convolvulus arvensis) and Hedge Bindweed (Calystegia sepium). These plants are the ones classified as noxious or invasive weeds due to their ability to survive year after year. The leaves of the true invasive species are usually arrowhead or triangular-shaped, while the leaves of the annual ornamentals are distinctively heart-shaped. Another key difference is flower size: Field Bindweed produces small flowers, often less than one inch across, whereas many ornamental Morning Glories have blooms that are two to three inches wide.
Characteristics of Aggressive Growth
The invasive status of bindweeds stems directly from their specialized biological structure, which allows them to survive repeated top-growth removal. Field Bindweed, in particular, establishes a deep taproot and extensive lateral rhizomes. The main taproot can penetrate the soil to depths of 9 meters, while lateral roots may spread horizontally for up to 60 meters, creating a dense, interconnected mat beneath the soil surface.
This extensive root system serves as an energy reserve, enabling the plant to quickly regrow even after the above-ground vines are cut back. Furthermore, the root system is brittle, meaning that mechanical disturbance, like tilling, fractures the roots into smaller pieces, and each fragment as small as two inches can regenerate into a new plant. The seeds produced by these perennial weeds are highly persistent, capable of remaining dormant yet viable in the soil for up to 30 years, contributing to a long-lasting seed bank. The vines themselves rapidly twine around desirable plants, effectively smothering them by blocking out sunlight.
Strategies for Managing Infestations
Controlling an established infestation of perennial bindweed requires a long-term, integrated approach that combines mechanical, cultural, and chemical controls. Hand-pulling the vines is effective only if done consistently every two weeks for a minimum of two years, as this repeated removal eventually starves the deep root system of carbohydrates. Tilling or chopping the roots with garden tools is discouraged because it fragments the rhizomes and spreads the infestation to new areas.
Cultural methods focus on soil coverage to eliminate light, thereby depleting the plant’s energy reserves. Smothering the area with thick layers of black plastic, heavy mulch, or landscape fabric can be successful but requires the material to be in place for several consecutive years to fully exhaust the root system. Planting dense, competitive cover crops, such as winter wheat or vigorous grasses, can also help suppress bindweed growth by shading the soil surface and limiting the resources available to the weed.
Chemical control relies on systemic herbicides like glyphosate, dicamba, and 2,4-D, which move through the plant’s vascular system to kill the root system. The timing of application is critical for effectiveness, with the best results occurring in the late summer or fall when the plant is moving carbohydrates from the leaves down to the roots for winter storage. Applying the herbicide when the plant is in the bud or full bloom stage ensures maximum translocation of the chemical to the deep rhizomes. A successful management plan typically involves repeat applications over multiple seasons to achieve substantial long-term suppression.