in a small area around my mailbox i had some trouble with weeds, so i added some preen (alot) to the soil and a few weeks later i planted some daisy's. well the daisys quickly died so i planted some marigolds, well they died too. next i planted black eyed susans, now they lasted a little longer than the others but they to are starting to croak. could it be the preen? did i add to much and now the soil is poisoned? thistle are still popping up but not as many just a few (for now)

will the black eyed susan be able to reseed itself? or will the preen prevent the black eyed susan seeds from germinating next spring?