Recycled jars can be transformed into just about anything...including a pot plant! For this project, I used an old pasta sauce jar. After washing and drying, I covered it with paper cuttings from a brochure that arrived in my mailbox, as I quite liked the design and the paper was nice and thick. To secure the paper cuttings in place over the jar's curved surface, I used strips of cellophane tape. This was also to sort of "waterproof" the jar as water can be wiped off a cellophane-taped surface quite easily without wetting the paper cuttings underneath it.
Warning - this only works for certain plants. Not all can survive in water alone. You'll also need to take a cutting from an existing plant as it's not likely to work with a seed. I did initially hope to be able to put earth in the jar, but found out that without drainage, no plant would be able to survive. So I tried water. That worked pretty well... for this little plant anyway :-)