Tulbaghia violacea, commonly known as Society Garlic, is a popular herbaceous perennial valued for its delicate lilac-pink flowers and deer-resistant, garlic-scented foliage. Gardeners often seek to understand its growth habit to prevent it from overrunning garden beds. Society Garlic is generally characterized as a clumping perennial, not an aggressive runner, despite being a vigorous grower that forms dense masses. It increases its footprint through two distinct mechanisms: one primarily underground and the other through aerial dispersal.
How Society Garlic Spreads Underground (Vegetative Growth)
The primary method of expansion for Society Garlic is through slow, subterranean growth driven by its rhizomatous structure. The plant does not possess true bulbs but uses a cluster of tuberous roots attached to a basal plate, which acts as a short, slowly spreading rhizome. This underground structure continuously produces new offsets, or small, genetically identical plantlets, immediately adjacent to the parent plant. This process results in a steady and predictable lateral expansion of the original clump.
The rhizome system causes the central mass to become increasingly dense, rather than sending out long, aggressive runners that pop up meters away. The ever-widening clump slowly expands its diameter, maintaining a controlled presence in the garden. This slow, gradual growth rate means the plant will not colonize distant parts of a bed in a single season. However, allowing the plant to remain undisturbed for several years results in a large, tightly packed mound of foliage that may require management.
The Role of Seeds in Propagation
Sexual reproduction provides a secondary pathway for Society Garlic to increase its numbers through seed production. After the long flowering period, which often extends from early summer into fall, the spent umbels mature and develop seed capsules. If these capsules are left on the stalk, they will eventually dry and release small, black seeds onto the surrounding soil.
These seeds can germinate to establish new, volunteer plants, leading to a scattered pattern of growth away from the main clump. While seed propagation is a viable method for horticulturists, it is typically a minor contributor to unwanted spreading in a maintained garden setting. If unmanaged, however, a dense population of seedlings can establish themselves near the original plant, contributing to a crowded appearance. The resulting seedlings will take longer—often a year or two—to reach the mature, flowering size.
Practical Methods for Containment and Control
Managing the spread of Society Garlic involves addressing both its vegetative and sexual reproductive cycles. To control the slow, physical expansion of the clump, periodic division of the rhizomes is necessary. Gardeners should plan to dig up and separate overgrown clumps every two to three years to maintain their size and vigor. This division is best performed when the plant is dormant, either in late autumn or early spring, before new growth begins.
Preventing secondary spread by seed is accomplished through deadheading. Removing the spent flower stalks, or umbels, before they ripen eliminates the chance of volunteer seedlings appearing. For situations requiring maximum containment, such as on a patio or a restricted border, planting Society Garlic in containers provides an effective physical barrier. The container walls prevent the rhizomes from spreading laterally into the surrounding soil.