Invasive of the Month: Multiflora Rose (Rosa Multiflora)

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Multiflora Rose is an extremely vigorous shrub that is nearly impossible for humans to control because of its super-sharp thorns borne on long, arching branches that can grow six feet a year in every direction. It thrives best in full sun but persists in partial shade, in a wide range of soil, as long as it has adequate draining. When it blooms in the spring, it has an intoxicatingly sweet scent and bright white flowers.

Why it’s a problem

Multiflora Rose is a native of Asia. It was imported 150 years ago as a rootstock to aid in propagating ornamental roses. Because it’s so difficult for even large animals to penetrate, it was widely planted as a living pen around fields. Its very vigorous growth habit, ability to grow in a wide range of soil, water and light conditions, and lack of known controls have enabled it to rapidly take over fields and open areas, forming dense, nearly impenetrable mazes that crowd out other plantlife. Birds and other wildlife eat the small red hips and distribute the seeds. It often grows together with other invasive plants such as Oriental Bittersweet; in combination they are harder to approach and control.

What to do

Remove it. Like many invasive plants, controlling Multiflora Rose often takes several steps. For small plants, pull or dig them up by the roots during the growing season before they get larger. Seeds can linger for many years, so pull them again next year. Mature shrubs are difficult because their thorns make them hard to approach. Winter is a great time to tackle them: once the leaves have fallen, their woody central stems, some over two inches thick, are more visible. Use a pole saw, or a brush cutter with a circular saw blade, to reach through the thorny branches and cut the stems. Do this early in winter so that multiple snowfalls will flatten the dead branches. In the spring, the central stems can be removed either with hand tools or with a chain-equipped vehicle, removing as many of the roots as possible. In late summer and early fall, carefully paint freshly cut stumps with liquid herbicide. Large areas can be cut several times a year with a bush hog and tractor; this gradually weakens the shrubs as it prevents them from flowering, but usually does not eradicate them.

Want more information on invasive plants, events and the NOT WANTED campaign? Drop us a note via the Granby Conservation Commission webpage.