Does the attic reach freezing temperatures? If it stays even a few degrees above freezing, you can store all those things including the produce. (Apples/potatoes/onions...though it is best to separate apples and potatoes by quite a distance as they affect each other's longevity).
I would not store canned goods or cleaning supplies (or really anything liquid other than sugar syrup or something alcohol-based) where they will freeze. But boxed goods, syrup, cracker breads, teas and spices should be fine.
If you get freezing temps up there, you might think about using the back area of closets if you have them, under the bed, in a mudroom, under indoor stairs, under a tablecloth-covered table, or anything else you can think of. Apples, onions, and potatoes should stay fairly cold. We have an unheated closet where we store our apples; it gets down around 45-50 degrees in winter. The other things you mention, canned or liquid things, can be stored at room temp. I wonder if you would have space in or behind other furniture?
Good luck figuring it out.
Could we store the foods there? I plan on getting flours, beans and lentils, canned goods (tomatoes, apple sauce, agave sirup), breads (flatbread, toast), bulk teas and spices, cleaning supplies, etc. I personally think that the attic is too cold to store potatoes, onions and apples but that might be
Amanda, mom to Everest (12), Alden (10-1/2), Ellery (7-1/2), & Avery (6)