Gossamer summer / H.M. Bouwman.

Enhanced descriptions from Syndetics:

Four sisters find their summer vacation taking a magical turn when they stumble into the world of some rather unexpected fairies in this "heartwarming" ( Kirkus Reviews ) and "clever" ( The Horn Book , starred review) middle grade story that's perfect for fans of The Penderwicks .

It all started when Jojo saw a fairy but said she didn't. After all, fairies aren't real--and if they were, they wouldn't look like that! No, Jojo did not see a small, green, muddy...person. Her sisters have no problem believing, though. They beg Jojo to finish the story she started telling long ago, but since the death of their beloved grandmother, Jojo hasn't felt like talking about magic, even if her sisters still believe.

Instead, the sisters decide to make fairy gardens to entice the new kid across the street to come play. Their plan works, but it also catches the attention of creatures that bear an uncanny resemblance to the bedraggled fairies Jojo invented. Stories can't come to life, though--can they? Yet the danger is real enough. With the questionable help of a very self-satisfied cat, the sisters and their new friend, Theo, set off on an adventure to save the fairies from a flock of terrifying birds made of bones.

But making everything right again will require a different kind of magic: the magic of sharing stories...and letting go.