Ranunculus are highly prized garden plants, known for their dense, multi-layered flowers that resemble small roses or peonies. The cultivated varieties most popular are Persian Buttercups (Ranunculus asiaticus), which bloom in a broad spectrum of colors. The question of whether they “spread” causes confusion because their multiplication method differs significantly from weedy species. True Persian Buttercups do not rapidly colonize an area but instead slowly increase their numbers through a controlled, subterranean process.
How Garden Ranunculus Multiply
The multiplication of cultivated Ranunculus asiaticus is achieved through the annual production of new underground storage organs called corms. These corms, which look like small, clawed or octopus-shaped structures, function as energy storehouses for the plant. During the growing season, the original “mother corm” fuels the plant’s growth and flowering.
As the plant finishes blooming and the foliage begins to yellow and die back, the mother corm initiates division. It develops new, smaller daughter corms clustered around the base of the original organ. When the plant enters its dormant phase, a single planted corm may have multiplied into several distinct daughter corms. Gardeners who lift the plants for storage will find this cluster of new corms, each capable of producing a full plant the following season.
Identifying Aggressive Spreading Varieties
The misunderstanding surrounding Ranunculus spreading often originates from the existence of other species within the same genus, which possess very different growth habits. The most notorious is Creeping Buttercup (Ranunculus repens), which is a true spreader and often considered a lawn and garden weed. This plant utilizes specialized stems called stolons, or runners, which grow horizontally along the soil surface.
These runners root down at the nodes, establishing new, genetically identical plants that quickly colonize and cover large areas. This stolon-based propagation, combined with prolific self-seeding, allows species like R. repens to aggressively displace other garden plants. The cultivated R. asiaticus does not produce these spreading runners.
Visual cues make it possible to distinguish between the two types. The weedy Creeping Buttercup has simple, glossy, five-petaled yellow flowers and often features trifoliate (three-parted) leaves that may have distinct pale or silvery blotches. In contrast, the desirable Persian Buttercup is known for its finely cut, fern-like foliage and its dramatically multi-petaled, double blooms. The presence of above-ground runners is the clearest sign that a plant is one of the aggressive, weedy varieties.
Maximizing Corm Increase in Your Garden
Gardeners who want to encourage the multiplication of their Persian Buttercup corms should focus on providing optimal growing conditions. Proper drainage is paramount, as corms are susceptible to rot in wet, heavy, or poorly draining soil. Incorporating organic matter, such as compost, into the soil before planting helps to ensure the necessary rich, yet well-aerated, environment.
Once the foliage begins to yellow and die back, signaling dormancy, it is time to lift the corms. Allowing the leaves to die back fully is important, as this process ensures maximum energy is transferred from the foliage into the developing daughter corms. The corms should be carefully separated, dried thoroughly in a cool, dark location for about two weeks, and then stored until the next planting season. This division and proper storage prevents rot and ensures each new corm is ready to produce a full plant the following year.