Sukkut: Weaving Mats from Lulav Leaflets
Question
Is it permissible to weave a mat from the lulav leaflets or, alternatively, to throw the lulav away in the garbage? Similarly, would it be permissible to build furniture from planks used to place sechach on?
Answer
It is forbidden to use tahsmishei mitzvah, ritual items previously used for a mitzvah, for a secondary[1] purpose when they can still be used for their original intended use. Examples include using whole tzitzit strings that were already used for the mitzvah or a kosher shofar that has been blown on Rosh Hashanah, or using a sukkah or the arba minim during Sukkot, etc. Nevertheless, once they can no longer be used for their original purpose for various reasons (eg. worn-out tzitzit or the arba minim after Sukkot), the posekim differ on how to handle them.
Shulchan Aruch (OH 21:1) maintains that there are no restrictions on permissible uses of these items. His ruling is based on the Talmudic definition of tashmishei mitzvah as lacking inherent holiness (as opposed to tashmishei kedushah; see Megillah 26). However, Remah suggests avoiding degrading disposal methods, such as throwing them in the garbage. Mishnah Berurah (21:6) explains that this is out of respect for the past mitzvah use. He further relies on Shulchan Aruch's ruling (OC 664:8) that one should not walk on the bundle of aravot (a.k.a. hoshanot) after Sukkot. Therefore, one should not make mats out of lulav leaflets or sechach for the purpose of lying or walking on. However, it is permissible to place them in a designated area until they dry up (after they are shriveled, all permit discarding them in the garbage). They can also respectfully be placed in a spot where green clippings are collected. (Rabbi Moshe Bloom: It seems that they can also be thrown away in the garbage if first wrapped in a bag, as we discard terumah or food with kedushat shevi'it).
After Hoshanah Rabbah, some synagogues traditionally place the bound aravah branches on top of the aron kodesh. Some posekim, though, oppose this practice since it is disrespectful to the aron kodesh and because it is forbidden to place items that do not require genizah (since they are not tashmishei kedushah)[2] on the aron kodesh. However, one should not prevent established customs, considering that the aron kodesh was built with the expectation that the bound aravot branches would be laid on it after they are beaten.
Various possible uses for the arba minim after Sukkot are suggested by posekim, such as using them for other mitzvot, e.g., using them for fuel when baking matzot or when burning chametz; or incorporating hadas leaves into the besamim for Havdalah. It is also possible to make jam from the etrog. If these solutions are impractical, they can be burned right after Sukkot and this is not considered degrading.
Conclusion
Even after tashmishei mitzvah can no longer be used for their original intended purpose, they should still be treated with respect. It is forbidden to fashion mats from lulav leaflets or sechach since these mats are walked on. Certainly, the lulav and sechach should not be disposed in a regular garbage bin, rather placed in an area from where green clippings are collected. It is best to find a usage that does not degrade them, such as making a shade for the pergola, etrog jam, or myrtle liqueur. Ultimately, reusing them for another mitzvah is preferred, such as incorporating hadas leaves into besamim, weaving the lulav leaflets into a mat to be reused as sechach, or burning the lulav and sechach while baking matzot or with the chametz.
[1 For the article in Hebrew, including complete references, see here.
[2] Tashmishei kedushah include parchment with pesukim, such as a sefer Torah, mezuzah, tefillin; in contrast, tashmishei mitzvah do not include pesukim but are articles used for a mitzvah – shofar, sukkah, arbat haminim, tzitzit, etc.