Moshe in Ramat Beit Shemesh asks:

I have heard that produce which grows on Jewish fields in the sh’mittah
year is forbidden even if it grows by itself. Why?

are referring to the prohibition of s’fichin
(lit. after growth). The Torah only forbids sowing and planting in the sh’mittah
year. What was sown or planted beforehand or grew spontaneously is permitted.
However, our Sages were worried about cheating. Since produce which grew by
itself is permitted, some sly farmer might be tempted to secretly sow his field
at dead of night and then wonder at the “miraculous” crop which appears some
time later! To discourage such action, they prohibited eating and use of that
which grew on Jewish fields even if it grew by itself. This prohibition applies
to grains and pulses which reached one-third of their growth in the sh’mittah
year and vegetables which started growing in the sh’mittah
year, even if they were sown beforehand. Produce which grows wild is not subject
to this prohibition, nor are perennial plants and trees. Interestingly, bananas
are also not forbidden because of s’fichin,
even though the plant “dies” every year, for two reasons. Firstly, the
banana plant regenerates itself. Even though this year’s leaves die, a new
fruit-bearing section will appear next year without any need for replanting.
Secondly, it takes a year and a half from the time of planting the banana plant
till fruit appears. Thus, one who plants in the sh’mittah year (Heaven forbid) would have to wait a long
time for produce. Our Sages were mainly concerned about illegally obtained
produce within the sh’mittah

How can I acquire Otzar Beis Din produce?

Let us first explain what Otzar Beis Din
is. Sh’mittah-observant farmers
declare their produce ownerless. Anyone can take from this produce. However,
people are not going to travel up and down the country looking for ownerless
fruit and vegetables. Moreover, once the farmers have declared their produce
ownerless, they have no incentive to perform even permitted work to ensure that
the crop successfully ripens. Beis Din — always
concerned for the public good — therefore steps in to ensure that (a) any
permitted work to ensure the ripening of the crop is carried out and (b) that
the produce is then packed and distributed. Although they employ workers to
perform all these tasks, they do not acquire the produce. It remains ownerless,
until it reaches the hands of the consumer. The consumer does not pay for the
produce he receives, since it is forbidden to trade in sh’mittah
produce. He only reimburses the Otzar Beis
for their expenses in making the produce available to him. They
then use this money to pay their workers for their labor and expenses.
Otzar Beis Din
produce is distributed either through special
distribution stations or by sh’mitta
stores which operate in accordance with the opinion of the Chazon Ish (e.g. She’eiris
). Look out for the notices!