I have veggies and flowers planted in one of the grassy areas opposite the clothes shop. I've just tried to fertilise my flowers there, but am unable to do so (red square), but I have no problems using fertiliser within the botanical garden.

So, whilst we can plant things anywhere we like, it seems that if we wish to use Miracle Gro, thru must be planted within the confines of the garden.

Cheers, LDW, thanks to you omitting that nugget, I now have a LOT of transplanting to do…

Fertiliser only works for botanical garden AND fenced edges of houses.