It's simple.
I do not want to till and water large areas each season and clear them from debris.
So I want to plant fiber in the end of the season and cut it before planting new crops on the new season start. (Fiber grows all the year round and does not die on season change.)
And I need a lot of seeds and clay to produce fiber seeds.
Why don’t you just buy the cheapest seeds of the season and plant them on the last day of that season? Or plant forage seeds (spring, summer, fall, winter seeds) on the last day of the season? That’s what I like to do, especially winter seeds on the 27th or 28th since I farm them all winter long and end up with enough winter foragables for 2,500 to 3,000 seeds, and I only need 1,000 of them (900 to sacrifice to keep my land watered and tilled, 100 for the first day of next winter since I like to speed grow a batch before going all out in week 2). Yes, the seeds will wilt and die on day 1 of the next season, but the land will remain tilled, and will also be watered already if you have sprinklers covering those areas. All you have to do is clear them with the scythe, and then you can plant your new crops without having to worry about tilling and watering them.
Of course, that means losing some cash, but that’s easily made up elsewhere like mining and fishing since you don’t have to devote the time to hunting for clay and mixed seeds. And in summer, you can plant wheat seeds on the 25th (or 26th if those plots have deluxe speed grow on them) in any plots that are open, and they’ll be ready for harvest on Day 1 of Fall with the ground still tilled and watered.
Anyways, good luck on achieving your goals, how ever you decide to do it