From what i understand right now the seeded inventory works like this (not sure about depth)
Clothing item
Seeded item
Seeded item
Seeded item
Seeded item
Seeded item
Seeded item
No storage option
My suggestion is to classify the seeded items in multiple categories/sizes
Large, medium, small and tiny (just an example)
And these can only store a seeded item smaller than them alongside your other items
So for example
Large
Medium
Small
Tiny
only items
i think this will be a better option so you can still put items inside the lowest possible layer
this idea can of course be shaped into any form you like so for example take away the sizes and just deny the player from putting seeded items on the lowest layer