This invention provides a seed germination medium comprising an upper layer formed from a tissue paper having a weight of approximately 10-30 g/m2, the tissue paper being coated or impregnated with a waterproofing agent such that the tissue paper is permeable to gases but substantially impermeable to...http://www.google.es/patents/US6681521?utm_source=gb-gplus-sharePatente US6681521 - Seed germination medium
