I'd say you were safe to go outside now... I'm in growing zone 5a and will be putting my plants outside at the end of May.... but 11C is not bad - certainly not anywhere near freezing/frost...
Good luck!
probably want to protect it at night somehow. still quite cold.
do you get frosts this late? if not it's a good time. might want slightly warmer temps, if possible, but in some regions can't be picky.