Mortis123 wrote:On what season can I obtain tree seed?
Summer and Autumn.
But because some stupid stuff happens after spring, you can't obtain them on the first day of summer*. Some trees will take up to 4 days to start spawning seeds, maybe even more, though I recall 4 being the longest I've seen.
However, this depends on the individual tree, not individual type, so if you are looking for a specific seed in the wilderness, just keep searching for more trees. I've seen a birch tree spawn seeds in the first day, and another one only in the 4th day.