Hi @miu3731
I was confused by this too.
In the image, you have 2 options: Seeds or plants. You are currently in plants, meaning that you can go over the spots and see which plants are there. It's kind of an info mode.
If you gather seeds and you want to plant them, you have to switch to the Seeds side. Then you can actually plant the seed and see it grow.
Let me know if that helps you!
It does not allow planting of a seed in that area and it does not allow the weeding of that area either! Resetting the plot still shows there is a plant there although nothing is visually there!
