May I ask what growing zone you're in? (If you don't know, this USDA site can tell you. Just enter your zip code.)
If you could share photos of your carnation plants, I might be able to make some suggestions. It could be that they've outgrown the cups you planted in, and might have become rootbound. Are there drainage holes in the cups?
If you planted your garlic in the fall (as is typical), then the leaves are probably turning brown by now, which means it's time to harvest. If you planted in spring, then you may indeed have dead plants - garlic needs a long cool growing season to do well.
If you could share photos of your carnation plants, I might be able to make some suggestions. It could be that they've outgrown the cups you planted in, and might have become rootbound. Are there drainage holes in the cups?
If you planted your garlic in the fall (as is typical), then the leaves are probably turning brown by now, which means it's time to harvest. If you planted in spring, then you may indeed have dead plants - garlic needs a long cool growing season to do well.