Where do you get your info? From a variety of sources, primarily Edward C. Smith's "The Vegetable Gardener's Bible" and Suzanne Asheworth's "Seed to Seed". Also from seed catalogs; Southern Exposure Seed Exchange is especially helpful. And, of course, teh Googles.
When I logged in it said my last login time was December of 2000. Why? Tracking the login time was added in February 2010. I needed to set the old value of existing members to something, and that's what I picked.
Your data is incorrect. Different sources of information give widely differing data as far as optimum planting distances (especially for isolating plants for the purpose of saving seed), optimum soil temperature for germination, and so forth. If you see something that's obviously wrong, please click the "Contact Us" link at the bottom of each gardenplotter.com page and let us know about it, or post here in the Admin forum. Thanks for noticing, and for caring enough to help us correct it.