Disowning the Shemita produce of one’s land-Part 1:
A. The mitzvah:
It is a positive command of the Torah for one [whether a man or woman] to disown all the produce that grows on his land during the seventh year. [Accordingly, one must give all Jews access to collect the Shemita produce and one who prevents a Jew from entering to collect the produce transgresses this command.]
One who makes a fence around the field: Whoever fences his field to prevent people from entering it to take the produce transgresses this positive command. [In today’s times that Shemita is only rabbinical, this is likewise only a rabbinical transgression. However, it is permitted to have a fence around the field with an opening that allows people to enter freely as they wish.]
B. What produce must one disown?
One is only obligated to disown produce that is defined as Kedushas Shevi’is. This applies both in the seventh year and eighth year. Hence, fruits that are being collected in the seventh year, but do not have the status of Kedushas Shevi’is being that they grew in the sixth year, are not required to be disowned and made available for the public. [However, produce which is Safek Kedushas Shevi’is, such as fruits which blossomed prior to the 15th of Shevat, or Esrogim and lemons which were picked after Rosh Hashanah, are to be disowned.] On the other hand, produce which is been collected in the eighth year, but has the status of as Kedushas Shevi’is being that they grew during the seventh year, must likewise be disowned and be made available for the public.
Vegetables: Fields of vegetables which grew during the 6th year and will be collected in the 7th year must be disowned during Shemita. Vegetables which grew during the Shemita year are prohibited due to Sefichin and hence are not to be disowned.
Herbs and plants and a flower garden: All herbs and plants which are not designated for eating but are used for other purposes, such as for their scent, must be disowned and made available for the public. Certainly, if they are designated for eating, they must be disowned, so long as they do not have a status of Sefichin. If they do not have any purpose, then they do not need to be disowned. Thus, a garden which grows flowers and plants for beauty purposes is not required to be disowned if they do not serve any human benefit, even if they are considered edible for animals.
One’s lawn: A lawn of grass does not have to be disowned being that it does not contain any produce that is of direct benefit to humans, and is grown simply for the sake of beauty.
 See Maadanei Aretz [Rav SZ”A] 7; Shevisas Hasadeh Chapter 12; Yalkut Yosef Shemita 14; Halichos Hashevi’is [Oz Vehadar] chapter 16
 Rambam Shemita Veyoval 4:24; Toras Kohanim and Mechilta Parshas Mishpatim; Sefer Hachinuch Mitzvah 84
 Minchas Chinuch Mitzvah 84; Derech Emuna 4:169; Halichos Hashevi’is 16 footnote 2
 Regarding if one is required to disown the actual land, or simply disowning the produce suffices, see Maharsham 1:179 and Yalkut Yosef Shemita 14:2
 See Q&A regarding animals and Gentiles
 The reason: As the verse states “in the seventh year you shall disown it.” [Shemos 23:11]
 Shevisas Hasadeh 12:3; Or Letziyon 4:3; Halichos Hashevi’is 16 footnote 5
 Rambam ibid; See Maadanei Aretz [Rav SZ”A] 7:1 who questions the source for this statement and as to whether it is a Biblical or rabbinical prohibition
 Kesef Mishneh on Rambam 4:24; Mechilta
 Halichos Hashevi’is 16:2-3
 Chazon Ish 3:23; 12:7
 Chazon Ish 11:7; Halichos Hashevi’is 16:2-3
 Halichos Hashevi’is 16:4
 Halichos Hashevi’is 16:9