sometimes it takes more than 3 days for seeds to germinate your seed might not have been germ'd enough thats why the stem could have snapped because its to early in stage, when you germ seeds they should be 1/4inch with the seed still attached thats a good rule of thumb for planting, you plant 1/2-1/4 inch down in soil seed side up and it should grow the root should be whitish the more red it is the weaker the root and less chance it has of standing up although it still could (i have done it before) but it adds stess and we all know stress= bad but im to drunk to ramble on goodnight and good growing hope i could help =D