Allelopath turf wars: How did I not know this?
I am planting a mixed border including shrubs, wildflowers, Ipmoea Margarite and some smaller sunflowers. A few roses are included but they are several feet from the next plant. It turns out that the Ipmoea and sunflowers are allelopaths, they secrete substances that keep some types of nearby plants from growing well.
I find it amazing that plants war with each other this way, I had no idea.