Spinach

Bronze fennel produces allelopathic compounds that inhibit growth of many vegetables including spinach

Garlic exudates can stunt spinach growth

Bronze fennel produces allelopathic compounds that inhibit growth of many vegetables including spinach

Pokeweed produces saponins and other compounds that can inhibit growth of leafy greens

Giant reed creates heavy shade and produces allelopathic compounds that suppress nearby crops

Indian paintbrush is parasitic and can tap into roots of nearby plants, weakening them