This is the first time I have heard of gelatin being used for starting seeds. They have been using agar for decades for media for starting various kinds of plants. As Dimples mentions, these prepared mixes contain various minerals & nutrients for the developing plants. Gelatin & agar act similarly -- they both form gels. However, gelatin is a protein while agar is a polysaccharide (basically a sugar polymer). It is interesting that gelatin can be used for this purpose -- and its certainly a lot easier to find gelatin locally. Thanks for posting. I can't think of anything I would want to try it on but good to know about.