Two Plant-related Questions

What about the garage? For the cats, you can try putting some netting over them? I haven't had much success with keeping cats away from plants. Oh, maybe put them high, on a bookcase?

For the cold, if they are house plants, you need to worry about the dirt getting too cold for them, they aren't as hardy as outdoor plants. I think the sheet depends on how deep your porch is. on my back porch, I wouldn't worry, but on the front, I would have done the sheet too.

I remember hearing that cats do not like the feeling of aluminum foil under their feet - maybe you could try putting some large pieces of foil under the plants and see if they stay off it. Just a thought.

cats and dogs (and many animals actually) don't like cayenne pepper, so you could try sprinkling that in the soil around them to deter them.

i think you need to cover them.. also see what the cats don't like.. so spray some stuff around.. like vinegar in a sprayer.. if they walk away.. then try that.. it may be something else..

i dont know if this would work, but what about some type of a tomato cage? or a sprinkler guard (like to keep horses and cattle from breaking the sprinklers)? if they were large enough, you could just set it over the entire plant and pot. maybe go buy a roll of small fencing and make your own? i always put covers over my outdoor plants when its gonna freeze wether they're under the cover of a porch or not. good luck!

Do you have a garage? They would be fine there too. If they are protected on the porch, they don't need to be covered for a light frost, but you do need to water them before the freeze/frost. This helps protect them.
Good luck!