Commonly known as Butterfly Bush, Buddleia is a member of the Scrophulariaceae family. It is native to China and is often found growing in gardens across the country. Buddleia attracts a large diversity of butterflies.
Buddleia (Buddleja davidii)
Classified as a medium impact invasive species by the Irish National Biodiversity Centre. Not a Third Schedule listed species under Regulations 49 & 50 in the European Communities (Birds and Natural Habitats) Regulations 2011.
- Buddleia is easily identified by its bright, showy panicles of 4 lobed purple flowers that can also be white, pink, or red that are displayed on arching branches. They flower from June to September.
- Leaves are lanceolate and 10-20cm in length. Edges of the leaves are slightly serrated with a felted under surface.
- During the winter the flower heads and seed capsules remain on the plant.
- Plant can grow up to 4m tall.
- Buddleia seeds are small and produced in great quantities, up to 3 million can be produced per plant.
- Seeds can stay viable in the soil for several years.
- Most commonly found in Cork and Dublin, Buddleia thrives in waste ground and urban environments.
- It has become established across the country and colonises barren ground rapidly.
- Buddleia is a tolerant plant and can be found growing on walls, sub-soils, and rocky outcrops.
- They are therefore often found along new road schemes and waterways.
- Buddleia is reliant on insect pollinators, particularly butterflies.
- Seeds can be dispersed by wind, and sometimes water.
- Buddleia can also reproduce asexually from root and stem fragments.
- Abroad it poses a problem for flooding as its shallow root system means the plant is washed away often leaving the bank open to erosion and blocking the river downstream.
- Buddleia can form large stands where it becomes established.
- It can outcompete native plants for space and light
- Shades out caterpillar food plants and harms habitats for butterflies.
- It is a hardy plant, tolerant of a wide range of conditions.
- Mechanical: Physical control such as grubbing or pulling up Buddleia are applicable to small, initial stands of Buddleia. Buddleia can regenerate from cuttings, and it can grow back rapidly from the stump. If initial stands of Buddleia are pulled, the area must be planted to prevent new Buddleia seedling growth.
- Chemical: Chemical control is carried out by drilling the base of the plant and applying herbicide into the drilled hole. Alternatively, to this method is to cut the base of the plant and paint on a layer of herbicide during active growth, in late Spring to early Summer. These methods are carried out for larger, more mature stands of Buddleia,
- Younger, smaller stands should be treated with herbicide by foliar spraying. This spraying should be carried out again six months later. All pesticide products must be used in accordance with the Good Plant Protection Practice and be carried out by a licensed professional.
- Biological: Biological control has been undertaken in New Zealand when the Buddleia Leaf Weevil, Cleopus japonicus, was released in 2006. The Buddleia Leaf Weevil feeds on the leaves of Buddleia and can cause significant damage to the plant. The Buddleia Leaf Weevil is considered an effective way of control of Buddleia in New Zealand.
(National Biodiversity Data Centre, Ireland, Butterfly-bush (Buddleja davidii), image, accessed 11 May 2022)