I made a garden bed in my yard one half is flowers other half is scallions and tomatoes will mulch hurt plants?

Will red mulch kill my garden plants???? I hear there good and bad let me know I have flowers too and onions and scallions growing the mulch is pulled away
so your telling me that only tomatoes and peppers will grow in red mulch beds?

How can I counteract the too strong taste of scallion in a dip made with cream cheese, red peppers & mayo?

I should have waited to put the scallions in at the last minute, but I mixed them in ahead of time and now the whole dip in taken over by scallion (kind of a sharp taste).