Hi, I currently collected, cosmo, zinnia, mammoth sunflwoer, and celosia seeds and was wondering do any of them need to be stratified? also can anyone tell me how to tell if a sunflower seed is good, about 2-3 weeks ago i cut off the flower heads of my mammoth sunflowers and have been collecting there seed as it falls out. Like what should it look like, mine are plump but may have been harvested prematurly is there anyway to tell, thanks