new member question: Mixed Substrates (good/bad idea?)

Hello there Permies, this is my first post, although i am always reading through the forums, so i guess i will be very awkward

This is my first time cultivating mushrooms (oyster), and i am doing so in a double bucket situation. I have quite a few questions... The buckets are similar in size, so there is a very tight space between both buckets, will this somehow affect the spread of my spawn negatively? I tend to air it out for a while once a day.

But my main question is regarding the mixing of substrates. I am using dried banana leaves and sawdust, with a wee bit of coffee grounds... i fear that maybe the combination could produce mold? Do any of you know if this might harm my mycelium?
Have you guys ever mixed multiple plants for a substrate? I would like any advice on this, if any of you know
thank you so much!!!
a big hug

Welcome to permies Ginna
I know nothing whatsoever about fungi, but I'm sure someone who does will help out!

from what ive read of growing gourmet and medicinal mushrooms by paul stamets(im still working through it)
mixed substrates can be ok, but you have to make sure there is a good mixture of structure and aeration, too fluffy of a mix and the mycelium wil be exhausted bridging the gaps and will have a lot of trouble forming mushrooms, if its too tight then there is not enough oxygen and the mycelium inside not only suffocates but you make way for bacterial contaminants that will further weaken the mushrooms mycelium

normally stamets mixes sawdust with straw or other wood, but i guess if there isnt any previous info on the matter, than experimentation is the way to go, and i'd encourage you try at least one with the mix:)