The Mishnah on Tu B'Svhat (and other "new years")
אַרְבָּעָה רָאשֵׁי שָׁנִים הֵם. בְּאֶחָד בְּנִיסָן רֹאשׁ הַשָּׁנָה לַמְּלָכִים וְלָרְגָלִים. בְּאֶחָד בֶּאֱלוּל רֹאשׁ הַשָּׁנָה לְמַעְשַׂר בְּהֵמָה. רַבִּי אֶלְעָזָר וְרַבִּי שִׁמְעוֹן אוֹמְרִים, בְּאֶחָד בְּתִשְׁרֵי. בְּאֶחָד בְּתִשְׁרֵי רֹאשׁ הַשָּׁנָה לַשָּׁנִים וְלַשְּׁמִטִּין וְלַיּוֹבְלוֹת, לַנְּטִיעָה וְלַיְרָקוֹת. בְּאֶחָד בִּשְׁבָט, רֹאשׁ הַשָּׁנָה לָאִילָן, כְּדִבְרֵי בֵית שַׁמַּאי. בֵּית הִלֵּל אוֹמְרִים, בַּחֲמִשָּׁה עָשָׂר בּוֹ:
There are four new years:The first of Nisan is the new year for kings and for festivals. The first of Elul is the new year for the tithe of beasts. Rabbi Elazar and Rabbi Shimon say: the first of Tishri. The first of Tishri is the new year for years, for shmitta and jubilee years, for planting and for [tithe of] vegetables. The first of Shevat is the new year for trees, according to the words of Bet Shammai. Bet Hillel says: on the fifteenth of that month.
The Mishnah on Tu B'Shvat with Explanatory Commentary
באחד בשבט ראש השנה לאילן כדברי בית שמאי בית הלל אומרים בחמשה עשר בו:
On the first of Shevat is the New Year for the tree; the fruit of a tree that was formed prior to that date belong to the previous tithe year and cannot be tithed together with fruit that was formed after that date; this ruling is in accordance with the statement of Beit Shammai. But Beit Hillel say: The New Year for trees is on the fifteenth of Shevat.
Torah Sources on Tithing
וְכִי־תָבֹ֣אוּ אֶל־הָאָ֗רֶץ וּנְטַעְתֶּם֙ כָּל־עֵ֣ץ מַאֲכָ֔ל וַעֲרַלְתֶּ֥ם עָרְלָת֖וֹ אֶת־פִּרְי֑וֹ שָׁלֹ֣שׁ שָׁנִ֗ים יִהְיֶ֥ה לָכֶ֛ם עֲרֵלִ֖ים לֹ֥א יֵאָכֵֽל׃
When you enter the land and plant any tree for food, you shall regard its fruit as forbidden. Three years it shall be forbidden for you, not to be eaten.
וּבַשָּׁנָה֙ הָרְבִיעִ֔ת יִהְיֶ֖ה כָּל־פִּרְי֑וֹ קֹ֥דֶשׁ הִלּוּלִ֖ים לַיהוָֽה׃
In the fourth year all its fruit shall be set aside for jubilation before the LORD;
וּבַשָּׁנָ֣ה הַחֲמִישִׁ֗ת תֹּֽאכְלוּ֙ אֶת־פִּרְי֔וֹ לְהוֹסִ֥יף לָכֶ֖ם תְּבוּאָת֑וֹ אֲנִ֖י יְהוָ֥ה אֱלֹהֵיכֶֽם׃
and only in the fifth year may you use its fruit—that its yield to you may be increased: I the LORD am your God.
עַשֵּׂ֣ר תְּעַשֵּׂ֔ר אֵ֖ת כָּל־תְּבוּאַ֣ת זַרְעֶ֑ךָ הַיֹּצֵ֥א הַשָּׂדֶ֖ה שָׁנָ֥ה שָׁנָֽה׃
You shall set aside every year a tenth part of all the yield of your sowing that is brought from the field...
מִקְצֵ֣ה ׀ שָׁלֹ֣שׁ שָׁנִ֗ים תּוֹצִיא֙ אֶת־כָּל־מַעְשַׂר֙ תְּבוּאָ֣תְךָ֔ בַּשָּׁנָ֖ה הַהִ֑וא וְהִנַּחְתָּ֖ בִּשְׁעָרֶֽיךָ׃
Every third year you shall bring out the full tithe of your yield of that year, but leave it within your settlements.
Hassidic teaching on meditative prayer in nature by Rebbe Nachman of Breslov (d. early 1800s)
Know! when we pray in the fields, all the herbs and grasses enter into prayer [with us], helping us and strengthening us in our prayer. This is the reason prayer is called SiChah (conversation [with God]), it is related linguistically to “SiaCh [shrubs/grasses] of the field” (Genesis 2:5). All the shrubs of the field empower and assist our prayer.
Know! when we pray in the fields, all the herbs and grasses enter into prayer [with us], helping us and strengthening us in our prayer. This is the reason prayer is called SiChah (conversation [with God]), it is related linguistically to “SiaCh [shrubs/grasses] of the field” (Genesis 2:5). All the shrubs of the field empower and assist our prayer.
"The Song of the Grasses" by Naomi Shemer (1930-2004) based on another Rebbe Nachman teaching
Know that each and every shepherd has his own tune. Know that each and every grass has its own song.
And from the song of the grasses the tune of the shepherd is made. How beautiful, how beautiful and pleasant to hear their song. It's very good to pray among them and to serve Hashem in joy, and from the song of the grasses the heart is filled and yearns.
This part is added on to the original teaching in the song:
And when the the heart is filled by the song and yearns for the Land of Israel, a great light is drawn forth and goes from the Land's holiness unto it. And from the song of the grasses the tune of the heart is made.
Hebrew Transliteration of the Song of the Grasses
Da l'kha shekol ro'eh ve ro'eh yeish lo nigun m'yuchad mishelo.
Da l'kha shekol eisev v'eisev yeish lo shirah m'yuchedet mishelo.
Umeishirat ha'asavim na'aseh nigun shel ro'eh.
Kamah yafeh, kama yafeh vena'eh k'sheshom'im hashirah shelahem.
Tov me'od l'hitpaleil beineihem uv'simchah la'avod et Hashem.
Umeishirat ha'asavim mitmalei haleiv umishtokeik.
Ukh'shehaleiv, min hashirah mitmalei umishtokeik el erets yisra'el.
Or gadol azai nimshakh v'holeikh mikdushatah shel ha'arets alav.
Umeishirat ha'asavim, na'aseh nigun shel haleiv.
Know that each and every shepherd has his own tune. Know that each and every grass has its own song.
And from the song of the grasses the tune of the shepherd is made. How beautiful, how beautiful and pleasant to hear their song. It's very good to pray among them and to serve Hashem in joy, and from the song of the grasses the heart is filled and yearns.
This part is added on to the original teaching in the song:
And when the the heart is filled by the song and yearns for the Land of Israel, a great light is drawn forth and goes from the Land's holiness unto it. And from the song of the grasses the tune of the heart is made.
Hebrew Transliteration of the Song of the Grasses
Da l'kha shekol ro'eh ve ro'eh yeish lo nigun m'yuchad mishelo.
Da l'kha shekol eisev v'eisev yeish lo shirah m'yuchedet mishelo.
Umeishirat ha'asavim na'aseh nigun shel ro'eh.
Kamah yafeh, kama yafeh vena'eh k'sheshom'im hashirah shelahem.
Tov me'od l'hitpaleil beineihem uv'simchah la'avod et Hashem.
Umeishirat ha'asavim mitmalei haleiv umishtokeik.
Ukh'shehaleiv, min hashirah mitmalei umishtokeik el erets yisra'el.
Or gadol azai nimshakh v'holeikh mikdushatah shel ha'arets alav.
Umeishirat ha'asavim, na'aseh nigun shel haleiv.
Hassidic Teaching on Wisdom/Torah in Nature from Menachem Nachem of Chernobyl - late 1700s - translated by Rabbi Matthew Ponak:
The Torah, even though it was not given before the flood [of Noah], was still in this world. [This is] because the energy of the Maker [God] is in the made [i.e. the natural world]. The Torah was not [originally] given with “clothing” [i.e. stories which both conceal its inner wisdom and make it more accessible] as it was later at the giving of the Torah [at Sinai] when it was garbed in the garments of this world. There were a special few [before the flood] that were fulfilling the Torah as it is on High. They were perceiving it with expanded minds to the point that they grasped its true inner essence, as it was before it was revealed [as a book]. [These were people] like Methusela, Enoch, and Adam that were students of Torah [embedded in nature].
The Torah, even though it was not given before the flood [of Noah], was still in this world. [This is] because the energy of the Maker [God] is in the made [i.e. the natural world]. The Torah was not [originally] given with “clothing” [i.e. stories which both conceal its inner wisdom and make it more accessible] as it was later at the giving of the Torah [at Sinai] when it was garbed in the garments of this world. There were a special few [before the flood] that were fulfilling the Torah as it is on High. They were perceiving it with expanded minds to the point that they grasped its true inner essence, as it was before it was revealed [as a book]. [These were people] like Methusela, Enoch, and Adam that were students of Torah [embedded in nature].