Smooth Sow Thistle – Most thistles are safe to feed tortoises however, I avoid the bristle and spine types as they can be very painful for humans to touch let alone a tortoise or turtle eat. SO! This weed is more common to start growing in early spring and get very large throughout summer. Flowers and Leaves are edible for tortoises, box turtles and some turtle species. Please remember to double check your species before feeding. If you are unsure, feel free to ask me a question via-tumblr OR google search.