Both crops and weeds have been found to contain compounds that can be considered allelopathic. These include crops such as barley, oat, wheat, rye, canola, mustard species, buckwheat, red clover, ...

“I had to research it, and apparently sunflowers have an allelopathic chemical that they secrete to inhibit the growth of surrounding plants,” explains Katie (@thehomesteadingrd). Allelopathic ...