The popular succulent known as Hens and Chicks (Sempervivum) is celebrated for its rugged hardiness and ability to thrive in challenging environments. The common name reflects the plant’s prolific growth habit: the mother plant, the “Hen,” surrounds itself with numerous smaller offspring, the “Chicks.” This low-growing, mat-forming succulent is designed to multiply rapidly, meaning the answer to whether they spread is an unequivocal yes.
Understanding Offsets and Runners
The primary way Sempervivum spreads is through asexual reproduction, creating genetically identical clones called offsets, or “chicks.” These small rosettes emerge from the mother plant on specialized, horizontal stems known as stolons, which are often referred to as runners. These runners extend outward from the central “Hen” rosette, allowing the new “Chicks” to root into the surrounding soil and establish their own independent root systems.
Once the offsets establish roots, the connecting stolon may shrivel, effectively separating the new plant from the mother. This continuous cycle allows a single plant to quickly colonize an area, forming dense, attractive mats of rosettes. Ample sunlight and well-draining soil encourage robust offset production. When left unmanaged, a solitary rosette can easily expand its colony to a spread of 30 centimeters or more in a single growing season.
Controlling and Utilizing Spread
Managing the spread of Hens and Chicks is a practical aspect of gardening that allows for both containment and propagation. To limit unwanted spread, plant Sempervivum in contained environments, such as shallow bowls, troughs, or the tight crevices of a rock garden. This physically restricts the space available for the runners to root. Utilizing a top dressing of grit or gravel around the rosettes also provides the sharp drainage they prefer.
Utilizing Offsets for Propagation
The offsets are simple to separate and transplant to new areas. The best time to divide the “Chicks” is during the spring or summer growing season, once they have reached at least a quarter of the mother rosette’s size. To remove an offset, gently snip the connecting stolon close to the mother plant with a clean tool, or gently twist the offset free.
After separation, allow the severed end of the offset to dry and form a protective callus over the wound for a day or two before planting. This crucial step prevents rot when the new plant is introduced to moist soil. The offsets, which are essentially clones, will root quickly when planted in a gritty, free-draining medium, ensuring a high success rate for propagation.
The Lifecycle of the Hen and Seed Propagation
While asexual propagation is the most common method of spreading, Sempervivum also spreads through sexual reproduction via seeds. This secondary method is triggered by the natural lifecycle of the mother rosette, which is categorized as monocarpic. Monocarpic plants flower once, set seed, and then the rosette that flowered dies.
Before the “Hen” rosette dies, it sends up a thick, tall flower stalk from its center, which produces star-shaped flowers typically in shades of pink, red, or yellow. This process requires the plant to use up its stored energy reserves, resulting in the death of the rosette after the seeds mature. The surrounding offsets that the mother produced beforehand are left to continue the colony, effectively replacing the parent plant.
Propagation from seed is possible, but it is a slower process, and the resulting seedlings may not perfectly resemble the parent plant due to natural hybridization. For the average home gardener, simply detaching and planting the abundant offsets remains the easiest and fastest way to guarantee new plants that are true to the parent variety.