Since it is possible to sell horse manure, why can't I buy it?

You could also use dog poop or fish. As for using other plants - think of it as compost? There’s plenty of wild plants around the worlds you could harvest for compost if you don’t want to use anything you’re growing yourself.

Thanks for your suggestions. 

I probably sound really difficult here, but I don’t have pets - so no dog poop.

I have a real issue with killing fish just to fertilise plants. I know they are not real, but the principle bothers me.

I will follow your suggestion about harvesting wild plants. But I still think EA need to be a bit more flexible with the fertilisers. If I can’t buy horse manure, it is a shame that I can’t use chook manure on normal gardens.

If I remember correctly, in sims 2 we could use raked up leaves to fertilise our veges. That was good, but a lot of work.

I get the impression that the creators of the sims don’t actually garden in real life, or swim.

But I do really enjoy the game.

and thanks for your reply.

@sheridanhoughton      Hello! I totally agree that we should be able to buy horse manure so I added my "me too". It would also be nice if we could use the fertilizer for sale at the garden shop in Henford-On-Bagley for all plants and not just on "crops".

In the meantime, I like @PipMenace 's idea of using wild plants. I've done this a lot and it works well.

If your heart is set on using horse manure for fertilizer, you might try visiting one of the households with horses like the Grove or Gooseman households. Eventually one of the horses will poop and you can put it in your inventory. You might also try creating a neighborhood stable with one or two unplayed sims and several horses. Whenever I visit mine, there are at least one or two manure piles waiting to be collected. I've shared my neighborhood stable household to the Gallery if you're interested; #RanchersRush. The household has two humans and six horses. I've also shared a couple variations of their lot; #RoanRidersRanch.

At any rate, I do hope the team investigates and works on adding manure for sale and the ability to use crop fertilizers on any plant to the game.

I really like the idea of a neighbourhood stable. thanks so much. I will see if I can get hold of yours from the gallery.

thanks again.