Ma'asros5: 1
הָעוֹקֵר שְׁתָלִים מִתּוֹךְ שֶׁלּוֹ וְנָטַע לְתוֹךְ שֶׁלּוֹ, פָּטוּר. לָקַח בִּמְחֻבָּר לַקַּרְקַע, פָּטוּר. לָקַט לִשְׁלֹחַ לַחֲבֵרוֹ, פָּטוּר. רַבִּי אֶלְעָזָר בֶּן עֲזַרְיָה אוֹמֵר: אִם יֵשׁ כַּיּוֹצֵא בָהֶם נִמְכָּרִים בַּשּׁוּק, הֲרֵי אֵלּוּ חַיָּבִין.
[If] one uproots sets from his own [field] and replanted [them] in [another section of] his own [field], they are exempt [from tithes].  [If] one buys [produce] which is attached to the ground, it is exempt [from tithes].  [If] one harvested [produce] to send to his friend, it is exempt [from tithes]. R' Elazar ben Azaryah says: If similar [produce] is being sold in the market, this [produce] is obligated [in tithes].
Ma'asros5: 2
הָעוֹקֵר לֶפֶת וּצְנוֹנוֹת מִתּוֹךְ שֶׁלּוֹ וְנוֹטֵעַ לְתוֹךְ שֶׁלּוֹ לְזֶרַע, חַיָּב, מִפְּנֵי שֶׁהוּא גָרְנָן. בְּצָלִים, מִשֶּׁהִשְׁרִישׁוּ בָעֲלִיָּה, טָהֲרוּ מִלְּטַמֵּא; נָפְלָה עֲלֵיהֶם מַפֹּלֶת וְהֵם מְגֻלִּים, הֲרֵי אֵלּוּ כִנְטוּעִים בַּשָּׂדֶה.
[If] one uproots turnips or radishes from his own [field] to replant in [another section of] his own [field] for [their] seeds, he is obligated [to tithe them], because it is their “goren.”  Onions, once they have taken root in the attic, become cleared of [their] capacity to convey tumah. [If] debris fell on [the onions], and they are uncovered, they are [treated] as though they were planted in a field.