Don't eat the Daffodils

A rest day after yesterday's exertions = a  day of domestic chores including watering the flowers because despite it being April,  April showers are few and far between.  We planted daffodil bulbs along our functional and not particularly attractive "stock proof fence " border with the sheep field. Interestingly, the sheep do not eat them even though they eat most other flowers on the border,  which is just as well because I have just read that they are poisonous . I wonder how the sheep know? Even the lambs don't eat them.  Our title deeds say we must not plant yew on the border but says nothing about daffs.