The Star of Bethlehem (Ornithogalum umbellatum) is a cool-season perennial that often transitions from a desirable ornamental garden plant into a tenacious and difficult-to-control invasive weed. Its presence is marked by low-growing, grass-like foliage featuring a distinct white stripe down the center of each leaf, followed by small, six-petaled white flowers. Its persistence stems from its nature as a bulbous plant, which reproduces aggressively through the formation of numerous underground offsets known as bulbils. This reproductive strategy allows the plant to store significant energy reserves beneath the soil, making surface-level control techniques largely ineffective against established infestations.
Manual and Cultural Removal Techniques
Physical removal offers an immediate, non-chemical solution for controlling Star of Bethlehem, but it requires meticulous attention to detail to prevent inadvertently worsening the problem. The goal of manual removal is to extract the entire bulb structure, including all the tiny offsets that surround the parent bulb. Attempting to dig out the plants is most successful when the soil is slightly moist, which helps keep the entire mass of bulbs and roots intact.
Disturbing the soil with a shovel or hoe without complete removal is counterproductive, as this action can shear the bulbils from the main bulb, multiplying the infestation. Once the bulb clump is removed, it should never be added to a compost pile, as the bulbils can survive and be reintroduced elsewhere in the garden. For small, isolated patches, use a narrow trowel to carefully lift the entire cluster of bulbs and soil.
For larger areas, repeated cutting of the foliage over multiple growing seasons can weaken the plant. This cultural control technique works by depriving the plant of the energy produced through photosynthesis, forcing it to deplete its underground bulb reserves. While mowing or cutting the leaves will not eliminate the bulbs outright, consistently removing the green tissue prevents the plant from replenishing the energy needed to create new bulbils.
Another effective cultural tactic is to smother the area with thick mulch or an opaque material like black plastic sheeting. By blocking all incoming sunlight for at least a full growing season, the plant is unable to photosynthesize and cannot emerge from dormancy. This solarization method works best in areas where the appearance of the covering is not a concern, such as in flower beds that can be heavily mulched.
Chemical Control Strategies
Star of Bethlehem is difficult to manage with herbicides due to the protective waxy coating on its leaves and the deep energy storage of its bulbs. Chemical strategies must employ systemic herbicides designed to translocate from the foliage down to the underground reproductive structures. Non-selective herbicides containing active ingredients like glyphosate often provide only marginal control unless the plant’s waxy cuticle is physically damaged to improve absorption.
For control in turfgrass, herbicides containing active ingredients such as sulfentrazone or bromoxynil have demonstrated greater efficacy. Combination products that include broadleaf weed killers like 2,4-D, dicamba, and MCPP can also be used, but these often require multiple applications. The crucial factor in chemical control is the timing of the application, which must coincide with the plant’s active nutrient transport.
Effective windows for application are in the fall, as the plant moves energy down for winter storage, or in early spring, after the leaves have fully emerged but before summer dormancy. Applying the herbicide during these periods ensures the chemical is carried directly to the bulb, maximizing its impact on the underground structure. Careful application is necessary to prevent drift onto desirable plants, and treatment often needs to be repeated in successive seasons.
Sustained Management for Complete Eradication
Eradication of Star of Bethlehem is a long-term commitment that extends beyond the initial removal or chemical application. The plant’s bulbils can remain dormant and viable in the soil for several years, meaning that even a cleared area will likely see new emergence. Continuous, multi-year monitoring is therefore essential to intercept any new growth before it can mature and produce additional offsets.
Any newly sighted foliage must be immediately spot-treated with a targeted manual or chemical method, preventing the young plant from developing a new energy reserve. This vigilance is particularly important in the early spring and fall when the plant is most active above ground.
After the initial infestation is controlled, amending the soil and planting competitive groundcovers or turfgrass can help prevent the re-establishment of the weed. Dense, healthy plantings naturally shade the soil surface, which inhibits the germination and growth of any remaining dormant bulbils. By establishing a robust plant community, the area becomes less hospitable to the invasive weed.