top of page

Black swallow-wort

Vincetoxicum nigrum

What is it?

Black swallow-wort (BSW) can look deceptively benign when young, but this dark-leaved vine excels at blanketing and smothering native tree seedlings, among other vegetation. It is related to native milkweeds; its pods contain white-tufted seeds that drift on the wind to the neighbors. However, unlike its native cousins, BSW alters soils to prevent native plants from germinating; It lures Monarch butterflies to lay eggs on it rather than on native milkweeds. Unfortunately, the caterpillars that hatch soon die from eating BSW poison.

When to remove?

June - plants emerge; Flowers all summer into Fall alongside maturing pods Jun-Sep; Pods develop all summer - start opening in July (sunny sites), August (shadier sites) ; June - Dig small plants before they develop as long vines; Summer season - two part removal - Cut vines with shears to about 4-6 inches to get all pods quickly by mid-Aug - then dig out later up to Sept/early Oct.

How to remove?

Most successful with new, small populations of very young plants. Plants may be dug out if it is possible to remove the entire root crown. Any root that remains will likely regrow into new plants. If there is a larger patch of plants that have already developed pods, start by cutting the vines with shears to about 4-6 inches to get all the pods quickly, then go back and dig out the plants as time permits. You can use a trowel or digging knife, but better results can be had with a narrow shovel such as a trenching shovel, drain spade or transplanting shovel.

How to dispose?

Root crowns, fragments, and seedpods should not be left on the ground or composted, as they will resprout or germinate. Plants should either be burned or placed in sealed bags and disposed of in a municipal landfill.

bottom of page