Garden Fairies exist...
But not in the way we thought.
A strange form of life borrowing traits from insects and plants with a human-like appearance.
This is a reality-check, is what I am about to suggest at all possible? What improvements need to be made to make it plausible.
Aside: how these fairies evolved to be like they are is not important, as long as their present form is plausible.
The fairies have elongated limbs (rather insectile but four limbs and one trunk/main body part, humanoid face) and large thin wings. This is to increase surface area to volume as they photosynthesise (have chloroplasts). The volume is further decreased by them not being taller than five centimetres. They must roughly conform, especially at a distance, to the general look of a european flower fairy
They do not fly but due to their large wings (butterfly like proportions), small size and hollow bones (fairies are delicate) they can glide. (Mom I saw a tiny flying human in the garden!) I chose for them not to fly because I was worried it would be to energy intensive but it would be a bonus if they could.
To supplement their diet I thought they could, much like aphids, drink plant sap. (Who said fairies love plants?). To do this successfully they would need a stylet like an aphid so maybe like scientists they kill aphids and use the aphid's stylets. Else they could have very thin fingers that can make a small hole which allows sap to gush out.
If they use aphid's stylets, fairies would encounter hard times when aphids are sprayed to death (no more tools, no more sap).
So they would love to sunbathe and would stay around plants.