Is Crocosmia Lucifer Invasive? How to Manage Its Spread

Crocosmia ‘Lucifer’ is a popular garden plant, admired for its vibrant, fiery red flowers that bloom in mid- to late-summer. Its arching stems and sword-like foliage add dramatic structure to perennial borders, and it is a relatively low-maintenance and hardy plant. Many gardeners who grow it, or are considering it, ask whether its vigorous growth habit means it is an invasive species.

Defining Invasiveness in Plants

The term “invasive” has a specific ecological meaning that often differs from a gardener’s use of the word. In a scientific context, an invasive species is a non-native plant that escapes cultivation and spreads into natural ecosystems, causing environmental or economic harm. These plants outcompete native species for resources, disrupt local food webs, and can alter the physical environment. A plant that is officially designated as invasive may be subject to regulations to control its sale and distribution.

This is distinct from plants that are merely aggressive spreaders within the confines of a garden. These vigorous plants can quickly colonize a flowerbed and crowd out their neighbors, but they do not typically pose a threat to surrounding natural habitats. Their spread is an issue of garden management rather than ecological preservation.

While some species of Crocosmia are considered invasive in certain parts of the world, the ‘Lucifer’ cultivar is not classified this way. In regions like the UK and most of the US, ‘Lucifer’ is not listed on official invasive species lists. It is, however, recognized for its aggressive spreading behavior in garden environments, which requires mindful management.

Crocosmia Lucifer Spreading Behavior

The primary method of spread for Crocosmia ‘Lucifer’ is through its underground corms. Corms are swollen, underground plant stems that store food, similar to bulbs. Each year, a mature corm will produce new corms on top of or alongside itself, leading to an ever-expanding clump. Over a few seasons, a single planting can become a dense mat of foliage and flowers, quickly occupying more space than originally intended.

The plant forms dense, interconnected colonies that can suppress the growth of less vigorous perennials planted nearby. While it thrives in full sun and well-drained soil, some gardeners report that ‘Lucifer’ can grow and spread robustly in a variety of conditions, including partial shade.

Crocosmia ‘Lucifer’ can also spread by seed, though this is a much less common and slower method of propagation compared to corm division. The conditions for successful germination are not always present in a typical garden setting, making volunteer seedlings less of a concern than the underground advance of the corms.

How to Manage and Contain Crocosmia Lucifer

One effective method for containment is to install an underground root barrier at the time of planting. A solid barrier made of plastic or metal, buried at least 12-18 inches deep around the planting area, can prevent the corms from spreading outwards into adjacent parts of the garden.

Regular division of the clumps is another management technique. Every two to three years, preferably in the spring, the entire clump should be lifted with a garden fork. The corms can then be gently pulled apart, and the newest, healthiest-looking ones from the top of the clump can be replanted, while the older, less productive corms are discarded.

If complete removal of a Crocosmia patch is desired, the entire area must be dug over carefully to locate and remove every corm. Even small, overlooked corms can resprout and re-establish the plant. For this reason, unwanted corms should not be added to home compost piles, as they can survive and spread from there.