Raizy from Mattersdorf asks::
Since all greens that grow from the earth are "hefker" is it
permitted to pick flowers and greens from the gardens that face the sidewalks?
Firstly, not all that grows from the earth is "hefker"
(ownerless). Only those items which have kedushas shvi’is fall into this
category. Thus, only flowers which are grown for their scent have kedushas
shvi’is according to all opinions. Those which have no scent may certainly
not be picked. It is questionable whether those which do have a scent but are
not grown for this purpose have kedushas shvi’is and they should
therefore not be picked. Greens usually do not have kedushas shvi’is,
unless they are edible, in which case they may be forbidden because of s’fichin.
Additionally, there is a difference of opinion as to whether sh’mittah
produce is automatically hefker (Mabit/Maharit) or needs to be
declared ownerless (Beis Yosef). Even though the former opinion is
generally accepted, it is worthwhile checking that the produce has been declared
hefker before picking.