You can combine them into a mix IF you are sure they are all well dried. otherwise you risk ruining the kale and spinach if the gus or carrots have any moisture left in them. Learned that the hard way. So I usually mix all my dried leafy greens but keep the thicker, more coarse, items separate.

Onions I coarse chop for dehydrating and stir them up a bit now and then during the drying process. They stick together some but once fully dried are easy to break apart. Then they all go into Mason jars and lids. Be sure to do them outside or they will stink up the entire house for days. :)

Dave

Personally, I would put the spinach and kale into one bag, the gus in another, and the carrots into a third. They rehydrate a bit differently, and flavor up differently, so by the time your carrots are rehydrated, your gus could be overpowering the soup and potentially overcooked or undercooked depending on the gus and how you prepped it and your greens be overcooked. But I'm also a bit finicky about that sort of thing. For sure keep your greens and bigger goods separate though.

And yep to the onions like Dave said.. just run them through your food processor or mince by hand, and dry them out- make sure you use jelly sheets because those bits really shrink up while drying and will fall through the regular trays if unlined.