Rashi: Tzadikim. Radak - since they are compared to trees, it says that they are planted in a good, moist place - Beis Hashem. In the future, most Chachamim will be there.

Malbim: The Tzadik is compared to a cedar, for even when he is cut off from this world, he returns to grow tall in the world to come. Shesul is a tree that was uprooted and replanted elsewhere. Refer to 92:14:2:2.

Radak: They always stay there, for the Chachamim and teachers are there. In the days of Mashi'ach, all Resha'im will be eradicated, and Tzadikim will remain - "v'Amech Kulam Tzadikim" (Yeshayah 60:21). All will engage in Chachmah to know Hashem - "Ki Mal'ah ha'Aretz De'ah Es Hashem" (ibid., 11:9). Sprouting is succeeding and growing in Chachmah. The Kohanim and Leviyim are in Beis Hashem; Yisraelim are in the Chatzeros.

Malbim: A Tzadik is uprooted from his place in the physical world, which is called Chatzros Hashem, for it is like a courtyard in front of the house, i.e. the world to come - 'prepare yourself in the antechamber, in order that you will enter the banquet hall' (Avos 4:16). Then it is planted in Beis Hashem, i.e. the world of Neshamos. Sprouting "b'Chatzros Elokeinu" explains "Tzadik ka'Tamar Yifrrach" (verse 13), i.e. leaving children.