Hey Mr. Green,

I have bindweed throughout my yard. Since roots can be 10 to 20 feet deep, I can’t dig it out. Is there a safe poison to use that will not kill the bees? 

—L.F. in Sacramento, California

Bindweed, also known as creeping Jenny, wild morning glory, and the slightly more dignified Convolvulus arvensis can be one of the most frustrating weeds for gardeners to address. Its roots can plunge many feet down. And possibly even worse, its hard seeds can remain viable for 20 years.

Repeated, diligent pulling of the weed before it gets more than a few inches high in spring will eventually kill it. Another way is to thoroughly wet the soil when the weed emerges and then cover infected areas with at least 50 square feet of a double layer of two clear plastic sheets. If the area is larger, you can glue sheets together for added coverage. Be sure to secure the edges with bricks or boards to prevent any ambitious new shoots from slinking out from under the plastic.

Of course you could always try nontoxic pesticides made from soap, citric acid, or strong vinegar and clove oil. But remember, these will all require more than one application.