You need a large meadow, 25 seeds, and 25 manure fertilizer
If you have all of those you should be able to plant them, I did mine this morning

All of my fields are large. I'm hitting every parameter. It's never been a problem before, only today.

That's odd, it worked fine for me this morning

You're definitely trying to plant in a meadow (not greenhouse) and have the full 25 seeds required?

If so, take screenshots and send a note to contact us

(As a side note, I love your avatar )

I don't have any greenhouses either lol. I guess I'll have to send it in ugh

(Thanks! I like yours as well )

Hopefully someone can come along with more help since Contact us will be awhile, since it's the weekend

How do you even get pass seeds? I'm a new user and I got 20 via the tutorial thing, but idk how to get more.

I know people hate me saying this but you should try clearing cash and cookies. Its possible your device is short of space or holding old information. It is the first thing that Admin are likely to ask

You don't need equus to plant pass seeds

How do you get more pass seeds ?

Better start a new topic for a new question.

But to answer:
* on very rare occasions (such as the Howrse server anniversary) they are available in the shop. This will always be announced.
* you can win pass seeds in events
* some divines will give them, for example Caryopsis (Plant divine), Jack and the Beanstalk and the new Mushroom divine Flammulina
* some VIP players have a pass seed on their page as a UFO you can catch. But that is only 1 and you need 25 of them.

My guess is TS meant acres.