I don't have any suggestions but what a find!

For shashing, mabe green batik, wich will look good with the green of the sems and leaves. You do not want to detract from the beauty of the flowers. I am sure your mom will "see" what you are doing from up in heaven.

What a lovely thing to find..

I agree, sash with the light green, maybe pick up one of the darker colours in a narrow border, then a medium one for a wider border.

I read a few times to not use sashing and I think agree with that. Use a border or double border that compliments all the blocks and enhance the blocks themselves with the quilting. It is going to be stunning and a treasure that you will cherish forever.

I don't have any advice, but the blocks are beautiful and what a lovely keepsake from your mother.

Those are beautiful. Treasure them.

What would it look like to add sashing to the top like in applique. Might make the roses look like they were blooming on a trellis fence.

Beautiful work; such a treasure for you. Think I'd go with a soft green sashing, either a small print or a marble

I suggest that you border it with your mom's favorite color and call it "Mom's Flower Garden". What a family treasure!