Single threads would have the disadvantage that you would find them all over the forum thread list if not updated at the same rate. If you made them sticky they'd always stay on top, these seedling threads would soon cover the first page(s) of the forum threadlist.
What you propose sounds like a database/ plant list entry, Lynn. Using the Sempervivum Seedling category that also allows for comments (?) we might already have a proper solution. I would start at an earlier stage with the seedling discussion and update the photos if the seedling changes significantly in the following period. We could even keep the photos and add new ones with corresponding title - like "summer first year", "summer second year"... This way we had the whole seedling history at hand.
