How to farm?

[Pan]

I've set up the small farm, and bought the seeds from the hermit. However, after I plant and collect the goods, it tell me I need to till the land. After I till the soil I need to plant the seed again. that is normal. But I have to buy the seed again from the hermit, that is not right. each seed cost 23 coins I think, 6 plots that means 138 coins. Shouldn't it give out some seed after harvest?