There is a post (search for it) on Borg's Virtual Seed Tray (VST), a utility for Plant Tycoon, that lists what plants you have created, which ones you need, and lets you store seeds in a "virtual seed tray". It is not exactly a cheat -- you can opt to have spoiler info hidden, but it does come in handy when all three of your trays are full, full, full! Downloadable and simple, for Windows, and I found it very helpful in tracking and storing. Read the directions thoroughly on how to use it. If this is for you, then enjoy; if not ... that's quite alright at least you know :).