I got done making my daisies and they are drying and I picked one up to see how heavy it is and it is kinda heavy, will gum glue be strong enough I used the pme plunger cutters the daisies are 2 layers with a center. When I glue them on will I just have to hold it for a minute. I have never attached anything this big on the side of a cake yet.
I'm not sure what you mean by gum glue. I have used gumpaste glue or glue made with meringue powder but have found the easiest thing to use is a little dab of RI. Even on a fondant cake, I usually need some matching icing for borders or little details and royal is good for that so I usually end up making a small batch anyway.
You can consider mounting a toothpick or a piece of uncooked spaghetti on the back of the daisies with a small ball of gumpaste. You will still want to use a dab of RI or BC when you attach it to the cake. Whoever is serving the cake will need to know how they are attached, but it ensures the flowers will not fall off.