Looks a nice building to have you working place.
There are many grows possion to horses. A list I found :
acacia tree
bracken
Azalea
bastard clover
Belladonna
hogweed
Beech
Bittersweet
blue monkshood
Buttercup
Broom
datura
Oak
Spotted and water hemlock
Golden Rain
Fall-timeless
dog trot
Poppy
Ivy
tree of life
Privet
Nightshade
narcissus
rhododendron
Robinia
Oleander
pieris
comfrey
foxglove
spurge
black henbane
Note: this is not a complete list.
There are many grows possion to horses. A list I found :
acacia tree
bracken
Azalea
bastard clover
Belladonna
hogweed
Beech
Bittersweet
blue monkshood
Buttercup
Broom
datura
Oak
Spotted and water hemlock
Golden Rain
Fall-timeless
dog trot
Poppy
Ivy
tree of life
Privet
Nightshade
narcissus
rhododendron
Robinia
Oleander
pieris
comfrey
foxglove
spurge
black henbane
Note: this is not a complete list.