Reference for Sheviit 6:3

בְּצָלִים שֶׁיָּרְדוּ עֲלֵיהֶם גְּשָׁמִים וְצִמֵּחוּ, אִם הָיוּ הֶעָלִין שֶׁלָּהֶם שְׁחוֹרִין, אֲסוּרִין. הוֹרִיקוּ, הֲרֵי אֵלּוּ מֻתָּרִין. רַבִּי חֲנִינָא בֶן אַנְטִיגְנוֹס אוֹמֵר, אִם יְכוֹלִין לְהִתָּלֵשׁ בֶּעָלִין שֶׁלָּהֶן, אֲסוּרִין. וּכְנֶגֶד כֵּן, מוֹצָאֵי שְׁבִיעִית, מֻתָּרִין:

Onions that have had rain fall on them and have sprouted, if their leaves are black, they are forbidden. If they became green, they are permitted. Rabbi Chanina son of Antigonus said, If they can be plucked out by their leaves, they are forbidden. And [onions] similar to this, during the year after the Sabbatical year, are permitted.

Jastrow

Jastrow