Creeping buttercup rapidly spreads in southern Finland, posing gardening challenges

Rikkanenätti, commonly known as creeping buttercup, is an invasive weed that few would welcome into their garden. However, it is rapidly spreading, particularly in southern Finland. This perennial grass, characterized by its yellow flowers and height of 20 to 50 centimeters, uses runners to proliferate effectively. According to reports, the plant first arrived in Finland in the 19th century via ships, initially establishing itself around ports. By the latter half of the 20th century, its presence increased in cities due to suburban development, and it has now reached as far north as Oulu.

Creeping buttercup spreads quickly through its roots, which are fragile and easily broken during weeding. This leaves root fragments that can regenerate, making simple pulling insufficient for eradication.

Turku gardener Mika Lassila, familiar with the challenges posed by creeping buttercup, suggests using boiling water directly on the plants. While this may not eliminate the weed immediately, repeated applications a few days apart when new leaves appear can help. Another method Lassila recommends is covering the infested area with biodegradable fabric topped with mulch, effectively choking the plant. Additionally, safe, fat-based herbicides can be utilized, though they may also require multiple treatments.

Creeping buttercup can inadvertently be introduced to home gardens, particularly when purchasing shrubs or trees, as root fragments may be present in soil mixes. Lassila advises against ordering plants online from abroad, as this can result in the introduction of invasive species and pests. He notes that while garden centers in Finland are vigilant about controlling invasive species—with regular inspections—community plant swap events can also pose a risk for unintentional spread of creeping buttercup.