Do you know what type of trees were in there? It could have some black walnut or others that have a negative impact on other plants.Well, it might be the heat...but I'm starting to wonder if there's something wrong with my mulch. The peppers are doing better since I pushed all the mulch back to give them a 6 inch clearance between the peppers and the edge of the mulch. But places where the mulch is touching my nasturtiums, sunflowers, and dill, I've also got plants dying. Most of my nasturtiums are dying after reaching about 6"+. The sunflowers that don't have any mulch around them are doing great. The ones in the mulched area have either died or are stunted. That just seems like an awful lot of coincidence to me to not be suspicious of the mulch. It was a pile of green mulch (shredded bark, logs, leaves, pine needles, in addition to wood chips) that was dropped last spring (2021) so it has had a year to break down and compost a little. There's tons of fungi that grows on that pile but I don't know what else would make it toxic or bad? It's not exposed to chemicals or anything...