Adorning the Shul with Greenery on Shavuos: Minhag Yisrael or Chukos HaGoyim?
Festooning with Foliage
In many shuls around the world, Chag HaShavuos represents ‘going green.’ I am not referring to becoming environmentally friendly, but green in a more literal sense. In honor of Shavuos, many shuls, such as Rav Breuer’s K’hal Adas Yeshurun (KAJ) in Washington Heights, New York, and Shomrei HaChomos in Ramot, Yerushalayim (Rabbi Fuch’s shul), receive entire forest-like makeovers. With branches forming a Chuppah-like canopy over the bimah, trees set up next to the Aron Kodesh, and greenery abounding, many entire shuls are festively festooned for Zman Mattan Torah.
Yet, we find that other shuls do perform some adorning, but in a much more minimalist manner, using only flowers and grasses. And of course, there are shuls where no special Shavuos decorating is done at all. Indeed, there is quite a varied spectrum of minhagim, with each Kehillah and shul following its own traditions. This article sets out to explore the main prevailing minhagim customary throughout Klal Yisrael in relation to this inyan, as well as their halachic background.
Minhag Replicating Mattan Torah
The great codifier of Ashkenazic halachah, Rav Moshe Isserlis, better known as the Rema, in Hilchos Shavuos (Orach Chaim 494: 3) writes that “V’nohagin lishtoach asavim b’Shavuos B’Beis Haknesses V’habatim zeicher l’simchas Mattan Torah”, that ‘the custom is to spread grass(es) on Shavuous in the shuls and in houses, as a remembrance to the joy of Mattan Torah’. Mentioned in various formats as the tradition of several early Ashkenazic authorities, including the Maharil and Terumas Hadeshen, as well as the Kehillos of Worms, Würzburg, Frankfurt, and Amsterdam, the Rema codified this minhag of greenery on Shavuos as proper practice.
There are several rationales given by our luminaries to explain the connection between our adornment of a shul for Shavuos and the actual day of Mattan Torah - history’s very first Shavuos, including:
- The Levush explains that since at the time of Mattan Torah, the pasuk specified (Shemos Ch. 34: 3) that the cattle and sheep were prohibited to graze in the area, implying that Har Sinai (which was in a desert) became surrounded by grass at that time. Therefore as a Zecher l’Mattan Torah, we do the same.
- The Maharil, who seems to be the earliest mention of this minhag, states that the custom is to festoon the shuls specifically using fragrant grasses and flowers. Several sefarim source this to the Gemara Shabbos (88b) that elucidates the pasuk in Shir Hashirim (Ch. 5: 13) “lechayav k’arugas habosem… sifsosav shoshanim,” ‘your cheeks are akin to bundles of spices… your lips like flowers,’ to be referring to Mattan Torah. Every dibbur that Hashem spoke filled the world with an ethereal fragrance. Therefore, in commemoration, we spread aromatic flowers on Shavuos.
- The Bnei Yisaschar cites a mashal of the Midrash Rabbah about a king in his orchard, to explain that Bnei Yisrael at Har Sinai were “K’Shoshana Bein Hachochim, akin to a rose among thorns”(Shir Hashirim Ch 2: 2), to mean that in the zechus of Bnei Yisrael’s united and unequivocal declaration of ‘Naaseh V’Nishma,’ the world was saved. Therefore, to symbolize this, on Zman Mattan Torah we adorn our shuls with flowers.
Interestingly, the Chid”a cites an early, albeit infamous, source for this minhag that also evidences its antiquity: none other that the vile and villainous genocidal madman, evil Amalakite, and overall arch-enemy of the Jews, Haman HaRasha. According to the Targum Sheini on Megillas Esther, during Haman’s diatribe to king Achashveirosh haranguingKlal Yisrael, and regaling him of all the ‘bizarre’ customs of the Jews, one of them was about the spreading and gathering of apples and flowers on the roofs of their shuls on Shavuos. Although we generally do not learn halachah from Agaddah, on the other hand, the Noda B’Yehuda explains that we still can and do glean Minhag Yisrael. Accordingly, and although performed in various communities with variations, nonetheless, we clearly see that this Shavuos minhag has early origins.
Trees Are Terrific
When discussing this minhag, the Magen Avraham adds another element: Placement of trees in the shuls, to commemorate the fact that Shavuos is Rosh Hashanah for Peiros Ha’Ilan, tree fruits (Gemara Rosh Hashanah 16a). Many later eminent authorities, including the Elyah Rabbah, Shulchan Aruch HaRav, Chavos Yair, Chok Yaakov, Ba’er Heitiv, Merkeves HaMishnah, and Rav Yaakov Emden zt”l, follow his precedent, citing this minhag as well. Consequently, in addition to the festooning of grasses and / flowers, many Kehillos add trees, granting their shuls a full forest-like effect.
The Minchas Elazar of Munkacs, in his sefer Shaar Yissachar, cites an allusion to this minhag from the Zohar Hakadosh inParshas Emor. Quoting the pesukim in Parshas Pinchas discussing the Yom Tov of Shavuos (Bamidbar Ch. 28: 26), the Zohar writes that Rav Shimon (bar Yochai) expounded on the pasuk of “Az Yeranenu Atzei HaYaar Milifnei Hashem,” ‘the trees of the forest rejoiced before Hashem’ (Divrei HaYamim I Ch. 16: 33; which we all know from reciting ‘Hodu’ daily), and then goes on to explain the Kabbalistic secrets of trees (‘Sod Ha’Ilan V’Atzei Chaim’). Hence, we see an important connection between trees and Shavuos.
It is reported anecdotally (although the facts are somewhat disputed) that the Chasam Sofer was very makpid on this minhag, and one year when the gabbai did not set up the trees in the shul for Shavuos, he did not live out the year. Other reports state that instead, his house burned down. Whichever way the story actually occurred, we may discern that the Chasam Sofer indeed placed trees in his shul in addition to the greenery of Shavuos.
On the other hand, we find that the Vilna Gaon forcefully and vociferously opposed this minhag, roundly condemning its practice. And according to his Talmid-Chaver, Rav Avraham Danzig zt”l, in both of his essential and renowned halacha sefarim, Chayei Adam on Orach Chaim and Chochmas Adam on Yoreh Deah,as well assefer Maaseh Rav, which details the Gaon’s personal hanhagos, the Gr”a actually and actively was ‘mevattel’ (abolished) this minhag from Klal Yisrael.
His reasons for doing so, was that in his day (and nowadays as well) the non-Jews set up trees in their houses of worship as part of their holiday service and festivities. The Gr”a maintained that if we continue to do so as well, it would be violating a basic Biblical tenet of “Chukos HaGoyim,” and is therefore essentially forbidden. But to properly understand this, some background is required.
In Parshas Acharei Mos, we are exhorted not to follow in the ways of the local non-Jewish populace, “U’Vichukoseihem Lo Seleichu.” According to the Rambam and later codified by the Tur and Shulchan Aruch, this prohibition includes manners of dress, haircuts, and even building styles. Tosafos mentions that this prohibition includes two distinct types of customs: idolatrous ones, and those that are nonsensical; implying even if they are not done l’sheim Avodah Zarah, with specific idolatrous intent, they would still be prohibited to practice.
However, other Rishonim, primarily the Ran, Mahar”i Kolon / Cologne / Colon (known as the Maharik), and Rivash, define the prohibition differently. They maintain that a nonsensical custom of the Goyim is only prohibited when it is entirely irrational, with no comprehensible reason for it, or when it has connotations of idolatrous intent. Likewise, following a custom that would lead to a gross breach of modesty (pritzus) would fit the category. On the other hand, they maintain, observing a simple custom of the Goyim that has no reference to Avodah Zarah, especially if there is a valid reason for its performance, such as kavod, giving proper honor or respect, would indeed be permitted.
Although the Vilna Gaon rejects their understanding of the prohibition, and the Gilyon Maharsha seems to follow Tosafos, nevertheless, the Rema explicitly rules like the Maharik and Ran, as does the Beis Yosef. Accordingly, they hold that as long as a custom is secular, with no connection to Avodah Zarah, such a custom may still be observed.
Most authorities over the generations, including the Mahari Kastro, the Imrei Aish, the Shoel U’Meishiv (Rav Yosef Shaul Nathanson), the Ksav Sofer, the Maharam Schick, the Maharsham (Rav Shalom Mordechai Schwadron), the Mahara”tz Chiyus, and more contemporarily, the Seridei Aish (Rav Yechiel Yaakov Weinberg), and Rav Ovadiah Yosef,zichronam levrachah,allrule in accordance with the Rema’s ruling, that as long as one has valid reasons for performing a specific custom, it does not necessarily get classified as the problematic Chukos HaGoyim, unless its origins are rooted in idolatrous practice. 
Opposition and Divergence - It’s Not Easy Going Green
Even so, regarding Shavuos, the Gr”a’ s opposition to setting up trees in shuls was so forceful, that he was actually mevattel the minhag. He explains that since our putting trees in shuls is simply a minhag, but not an outright Mitzvah, it cannot counteract the potential prohibition of Chukos HaGoyim present, since the non-Jews do so for religious purposes as part of their holiday worship.
On the other hand, several Acharonim, including the Shoel U’Meishiv and the Maharsham, argued with his assessment, and defending this custom, even referring to it as ‘Minhag Yisrael.’ They maintained that as long as we are performing the minhag for our own reasons, especially to give honor, we do not have to worry about the practices of other religions. They cite precedent from the Rivash, a Rishon, who allowed visiting a cemetery to mourn a niftar every day of Shiva, even though this was a custom most commonly practiced by Arabs; explaining that this does not fit into the category of Chukos HaGoyim. In this vein, they contend, the same should hold true regarding placing trees in our shuls on Shavuos.
An additional reason posited by the Maharsham is that the proscription of Chukos HaGoyim can only apply if we are performing the exact same action as the non-Jews. However, regarding trees, they place trees outside as well, whereas we only do so inside our shuls. Therefore, he avers, our minhag is still permitted.
A similar rationale is given by Rav Yitzchok Isaac Yehuda Yechiel Safrin zt”l of Kamarna, explaining that since our intent is not the same as theirs, but it just happens to be that we are performing similar actions, it is not considered Chukos HaGoyim. This is similar to the dispensation for one who works in the King’s palace, that he may dress accordingly and not be concerned with potential violations of Chukos HaGoyim.
An added wrinkle to this debate is that it is not entirely clear which minhag the Gr”a sought to abolish. Was he exclusively referring to trees? Or was his intention to argue that even grasses and flowers are now problematic? Authorities differ as to defining his intent.
For example, the Chayei Adam and Mishnah Berurah understood that the Vilna Gaon only opposed the minhag of placing trees in shuls due to Chukos HaGoyim; ergo, he never objected to festooning with greenery, and is therefore certainly permitted. In contrast, the Aruch Hashulchan, as well as several Talmidei HaGr”amaintained that the Vilna Gaon intended to put an end to any sort of Shavuos custom involving plant adornments, not just trees.
Minhagei Yisrael - Seeing Green?
This is why in practice, this minhag has a wide spectrum of variations in its observance.
Kehillos of Ashekenazic-German origin (Yekkehs), as well as most Chassidic communities, including Karlin, Belz, Sanz, Spinka, Skver, Chernobyl, Bobov, and Satmar, follow the minhag of the Magen Avraham and his defenders, especially as an allusion to this custom was found in the Zohar Hakadosh, and not only festoon the shul with greenery as per the Rema, but also place trees.
Many others, in deference to the general understanding of the Vilna Gaon’s position, do not employ trees in their adorning, but will still decorate their shuls utilizing flowers and grass, in essence following the Mishnah Berurah’ s conclusion. This is also the opinion of many contemporary Gedolim including the Chazon Ish, the Steipler Gaon, Rav Shlomo Zalman Auerbach, Rav Yosef Shalom Elyashiv, and Rav Yisrael Yaakov Fischer, zichronam levrachah, contending that the Vilna Gaon only opposed setting up trees, but not grass.
A third custom, based on the strict interpretation of the Gr”a’s ruling, as understood by the Aruch Hashulchan and several Talmidei HaGr”a, is not to bedeck the shul at all with any greenery – not trees nor grass nor flowers, as they are all viewed as potential violations of Chukos HaGoyim. Rav Moshe Feinstein zt”l ruled this way, and Rav Chaim Kanievsky zt”l was quoted as maintaining that this is the proper minhag, and accordingly, there is no Shavuos festooning performed in the famed Lederman shul in Bnei Brak. Some even refer to this custom of non-decoration as ‘Minhagei HaYeshivos.’
Curiously, there is no mention of any sort of Shavuos greenery adornment in Rav Yosef Eliyahu Henkin zt”l’s authoritative Ezras Torah Luach, even though he cites the two other main minhagim of Shavuos brought by the Rema, namely staying up all night and eating milchigs. To this author, this strongly implies Rav Henkin’s well-known predilection to following the rulings of the Aruch Hashulchan - one of the Gedolim from whom he received Semichah, and hence lending credence to the notion that his glaring lacuna of this minhag was intentional, intending to show that he meant to follow his Rebbi’s position on this matter.
Interestingly, this minhag, as opposed to the other Minhagei Shavuos, is also noticeably absent from Rav Yechiel Michel Tukachinsky’s essential Luach Eretz Yisrael – even though this minhag pertains specifically to shul observance. This also implies that “Minhag Yerushalayim’s” tendency to follow Minhagei Talmidei HaGr”a trumps alternate practice, and hence no mention of festooning with foliage.
Remarkably, there are several Chassiduses, including Chabad, Kamarna, and Munkacs, whose Rebbes have written in support, even strongly worded defenses, of the minhag to place trees in shuls on Shavuos, yet, their own community custom is not to do any Shavuos shul decorating.
Regarding Sefardic observance of the Shavuos greenery minhag, it seems from the fact that there is a noticeable lacuna as to its existence in the works of early Sefardic authorities, from the Rambam to the Shulchan Aruch, or even the later Ben Ish Chai, indicates that it is essentially an Ashkenazic minhag. Yet, we do find several Sefardic poskim over the centuries, including the Knesses Hagedolah, Chid”a, Rav Chaim Pala’ji, and the Kaf Hachaim, discussing the custom’s reasons and merits. In fact, nowadays, there are Sefardic shuls who do observe at least some semblance of the minhag. Perhaps this is due to Rav Ovadiah Yosef zt”l’s staunch support of the custom, referring to it as ‘Minhag Yisrael that is rooted in the words of Chazal.’
In conclusion, whether or not your shul on Shavuos resembles a grassy Har Sinai or some variation thereof, it is important to remember that “Minhag Yisrael Torah Hu,” so you can rest assured that by following the Mesorah of your Kehillah, you are properly observing Kabbolas HaTorah.
The author wishes to acknowledge Rabbi Gedalyah Oberlander’s excellent ma’amar on topic in Kovetz Ohr Yisrael (vol. 20; Sivan 5760).
This article is dedicated L’iluy Nishmas Maran Sar HaTorah Harav Shmaryahu Yosef Chaim ben Harav Yaakov Yisrael zt”l (Kanievsky), this author’s beloved grandmother, Chana Rus (Spitz) bas Rav Yissachar Dov a”h and uncle Rav Yeruchem ben Rav Yisroel Mendel (Kaplan) zt”l, and l’zechus Shira Yaffa bas Rochel Miriam v’chol yotzei chalatzeha for a yeshua sheleimah teikif u’miyad!
Rabbi Spitz’s serves as the Shoel U’Meishiv and Rosh Chabura of the Ohr Lagolah Halacha Kollel at Yeshivas Ohr Somayach in Yerushalayim. His recent English halacha sefer, “Insights Into Halacha - Food: A Halachic Analysis,” (Mosaica/Feldheim)contains more than 500 pages and features over 30 comprehensive chapters, discussing a myriad of halachic issues relating to food. It is now available online and in bookstores everywhere.
 For example, in some Kehillos, aromatic plants are / were passed around, while other shuls decorate(d) the Sifrei Torah with flowers. Some put branches on the wall, while others the Bimah, and others layer the floor with a ‘carpet’ of grass. Some place(d) pictures of flowers on windows and others hang / hung flowers in glasses from the ceiling. Some even throw / threw flowers as the Torah passes / passed by or place(d) flowers on top the Torah during hagba’ah. Others do / did some sort of flower and / or greenery decorating at home. These remarkable minhagim are all variations of the main custom of festooning with greenery for Shavuos. Many of these diverse minhagim are mentioned by the Kaf Hachaim (Orach Chaim 494: 53-59).
 See, for example, Minhagei Maharil (Hilchos Shavuos 20, pg. 160), The Hagahos on Rav Yitzchak Isaac of Tirna [Tyrnau]’s Sefer Haminhagim (Minhagei Chodesh Sivan 49), Leket Yosher (Minhagim of the Terumas Hadeshen; pg. 103), Rav Binyomin Halevi’s Machzor Maagalei Tzedek (pg. 87), Minhagos Varmiza [Worms] (pg. 255), Minhagim D’K”K Varmisha [Worms] (vol. 1: 102, pg.110), Rav Yosef Yuzpa Haan’s Yosef Ometz-Minhag Frankfurt (851), Minhagei Virtzburg (pg. 16-18), Minhagei Amsterdam (pg. 62), Rav Yehuda Aryeh of Modena’s ‘Shulchan Aruch’ (pg. 67), and Shnei Luchos Habris (Ner Mitzvah 7 and beg. of Maseches Shavuos 15; also cited in his additions to the end of his father’s sefer Emek Brachah, Likutim, Shavuos, pg. 265 in the 5745 edition, and later by the Magen Avrohom 494: end 9 and later Poskim). On the other hand, this author finds it interesting that this minhag is not mentioned in Rav Yosef Yuzpa Koschmann’s classic Noheg K’Tzon Yosef – Minhag Frankfurt.
 Interestingly, there are several differences between the Maharil’s version of this minhag (the earliest reliable source) and the Rema’s (the most common and widespread) version. The Maharil mentions using flowers and aromatic grasses in the decorating of the shul, as well as spreading the grasses on the floor, whereas the Rema does not, instead simply referring to decorating the shul with grasses. The Rema also adds decorating the house as part of the minhag, which is not mentioned by the Maharil (but is cited by the Leket Yosher). Also, the Rema cites this minhag as being a ‘Zecher L’Mattan Torah,’ while the Maharil considered it ‘Simchas HaRegel.’
 Levush (Orach Chaim 494: 1). This reason is also given by Rav Yaakov Emden in his Siddur Beis Yaakov (vol. 2, pg. 148: 2), and cited briefly by the Mishnah Berurah (ad loc. 10).
 Interestingly, as pointed out by Rabbi Eliezer Brodt in a recent ma’amar on topic (titled ‘Shetichas Asavim U’Prachim V’Ha’amadas Ilanos B’Chag HaShavuos,’ printed in sefer V’hinei Rivka Yotzais; 2017, pg. 212), the very first mention of such a minhag seems to be by R’ Emmanuel HaRomi in his controversial Machberes Emmanuel (pg. 398), written in 1321, but it was seemingly written in jest and based on a supposed ‘diyuk’ from Megillas Esther(Ch. 3: 15), “V’Hadas Nitnah B’Shushan Habirah,” ‘and the law was given in Shushan the capital.’ He opines that the pasuk should instead read Shoshan (meaning a type of flower) and that ‘das’ is referring to the giving of the Law, a.k.a. the Torah, meaning that the Torah was given in Sivan when flowers abound, so we should therefore use them to enhance our shuls. This so-called ‘drashah’ was obviously not taken too seriously to be considered the first source of a greenery minhag on Shavuos, especially as the Shulchan Aruch (Orach Chaim 307: 16) explicitly singled out this sefer to forbid reading it even during the week, as it is a ‘moshav leitzim.’ On the other hand, R’ Emmanuel HaRomi himself must have nevertheless been considered an ‘Adam Chashuv’ as the Chid”a lists him in his encyclopedia of Gedolim thorough the ages Shem Gedolim (vol. 2, pg. 22), and considers his work on Mishlei to be essential reading.
 See the Shevet Mussar’s Midrash Talpiyos (vol. 2 pg. 457, erech ‘dudaim’), Lekutei Chaver Ben Chaim (vol. 2, pg. 34, Lekutei Orach Chaim 494), Rav Chaim Pala’ji’s Ruach Chaim (Orach Chaim 494: 4) and Moed L’chol Chai (8: 33), as well as the controversial Chemdas HaYamim (Hilchos Chag HaShavuos Ch. 3, pg. 105, 3rd column). The Midrash Talpiyos adds an additional interesting reason based on the Alshich’s explanation (Parshas Vayetzei Ch. 30: 14) that Reuven found the ‘Dudaim’ ‘B’ymei Ktzir Chittim’ to be referring to Erev Shavuos. The Ramban (ad loc.) cites several definitions of what the ‘Dudaim’ might be, including a fragrant flower and fertilely drug. Accordingly, this means that Leah conceived Yissachar, the greatest Talmid Chacham of the Shevatim, on Shavuos night. To allude to this we festoon the shuls with fragrant flowers on Shavuos, Zman Mattan Torah. An alternate, but similar approach is given in the Pardes Yosef (Shemos Ch. 2: end 3) citing the Maharam Bennet, as well as in the Lekutei Yehuda edition of the Sfas Emes on Megillas Rus (printed in the 1950s; Lekutei Yehuda appendix, Inyanei Shavuos pg. 2), citing one of the previous Gerrer Rebbes zy”a. Since we know Moshe Rabbeinu was born on the seventh of Adar and was hidden for three months, before he was hidden in the reeds (a type of grass) on the banks of the Nile River, this means that he was actually saved by Basya on Shavuos.[As a side point, although Bas Pharoah’s true name was Bisya (Divrei HaYamim I, Ch. 4: 18), the Midrash Rabba (Vayikra, Parasha 1: 3) explains that this act of saving Moshe’s life merited her to be called “Basya” – daughter of Hashem.] As Moshe was the leader through whom we received the Torah, we commemorate by spreading grasses on Zman Mattan Torah [although according to this understanding they do not necessarily need to be fragrant]. Some make that same cheshbon in reverse, that if Moshe Rabbeinu was born on Zayin Adar, then nine months prior he must have been conceived on Shavuos. Rav Yitzchak Nissim Pala’ji (Yefeh L’Lev vol. 2, 494: 7) adds that Rashi explains the pasuk in Tehillim (45: 1) ‘Lamnatzeach al Shoshanim’, to be referring to Talmidei Chachamim. As such, on Shavuos, the Yom Tov of Talmidei Chachamim (see Pesachim 68b as to Rav Yosi’s feast on Shavuos, ‘ee lo hai yoma d’ka garam,kama Yosef eeka b’shuka’), we honor Talmidei Chachamim in this manner. The She’aris Moshe (Moadim U’Zmanim, Shavuos s.v. taam eisev) writes simply that ‘eisev,’ grass, stands for the three names of Shavuos - Atzeres, Shavuos, and Yom HaB ikkurim.
 Bnei Yisaschar (Ma’amrei Chodesh Sivan, Ma’amar 4: 7 & 8) citing Midrash Rabbah (Vayikra, Parshas Acharei Mos 23: 3 s.v. R’ Azarya).
 Birkei Yosef (Orach Chaim 494: 6). He cites it as ‘Aggadah’.
 Targum Sheini on Megillas Esther (Ch. 3: 8), according to Rav Mordechai Ventura’s Passhegen Haksav translation (from 5490; ad loc.). However, it must be noted that quite intriguingly, the word ‘flowers’ does not seem to be in the original Targum Sheini, nor in the other translations, commentaries, or similar Midrashim. In an attempt to solve this seeming enigma, in a recent ma’amar on topic (titled ‘Shetichas Asavim U’Prachim V’Ha’amadas Ilanos B’Chag HaShavuos’, printed in sefer V’hinei Rivka Yotzais; 2017, pg. 217), Rabbi Eliezer Brodt opines that it is conceivable that the Chid”a, as well as possibly, the Passhegen Haksav, were actually referring to the anonymous and controversial sefer Chemdas HaYamim, which seems to be the first to make such a connection between flowers on Shavuos as being alluded to in that passage of the Targum Sheini (in the 5771 version of Chemdas HaYamim, see vol. 2, pgs. 314, 315, and 571).
 See Yerushalmi Pe’ah (Ch. 2, Halacha 4), Rabbeinu Tam’s Sefer Hayashar (Teshuvos 45: 3), Rashbam (Bava Basra 130b, end s.v. ad sheyomru), Shu”t HaRashba (335), Shach (Choshen Mishpat 81: 56), Pri Chodosh (Orach Chaim 128: 20), Tosafos Yom Tov (Brachos Ch. 5, Mishnah 4), Shu”t Noda B’Yehuda (Tinyana Yoreh Deah 161), Shu”t Ba’er Yaakov (Even Ha’ezer 199), Shu”t Chaim Sha’al (vol. 1: 92),Machazik Bracha (Orach Chaim, Kuntress Acharon 51), Shu”t Maharsham (vol. 1: 163 s.v. hinei), Sdei Chemed (Maareches Alef, Klal 95 - 96, and Pe’as Hasadeh,Klal 39), Shu”t Emek Hateshuvah (vol. 2: 1 s.v. v’od), Shu”t Mishnah Halachos (vol. 9: 319 s.v. vhanlfa”d and u’ma”sh) and Shu”t Yechaveh Daas vol. 4: 33). Most authorities maintain that one may learn a halachah from Aggadah if it does not contradict any other Gemara or Halacha. See next footnote.
 See Tosafos (Avodah Zarah 33b) who gleans a different limud from Haman, and Shu”t Noda B’Yehuda (ibid. s.v. umah sheratzah) who makes this distinction, that all would agree regarding learning minhagim, that we may indeed do so from Aggadah.
 See Rabbi Gedalyah Oberlander’s excellent extensive ma’amar on topic in Kovetz Ohr Yisroel (vol. 20, Sivan 5760), which details variations of this minhag in many communities, in deference to the different rationales given for the minhag.
 Magen Avraham (Orach Chaim 494: 5 s.v. nohagin).
 Including the Elyah Rabbah (Orach Chaim 494: 12), Shulchan Aruch HaRav (ad loc. 14 and 15), the Chavos Yair’s Mekor Chaim (ad loc.), Chok Yaakov (ad loc. 7), Shulchan Shlomo (ad loc. 6), Chok Yosef (ad loc. 11), Ba’er Heitiv (ad loc. 7), the Merkeves HaMishnah’s Shulchan Tamid (vol. 2, Pesach Ch. 19: 4, pg. 105), and Rav Yaakov Emden in his Siddur Beis Yaakov (vol. 2, pg. 148: 3). Interestingly, many of them do not cite the last words of the Magen Avraham ‘vayispalelu aleihem,’ that we should also daven for the trees.
 Shaar Yissachar (Maamar Chag HaBikkurim 48), based on the Zohar (Parshas Emor, vol. 3 pg. 96a). Interestingly, the Munkacser minhag is not to festoon with grass or trees, even though their Rebbe defends the minhag. See also Darkei Chaim V’Shalom (737).
 We also recite the similar “Az Yeranenu Kol Atzei Yaar,Milifnei Hashem,” ‘all of the trees of the forest will rejoice, before Hashem’ (Tehillim 96: 12 and 13) weekly in Kabbolas Shabbos. TheNefesh Yehuda (Rav Moshe Frankfurt, Dayan of Amsterdam), in his commentary on the Menoras Hamaor (Chelek Shishi, B’Chag HaSukkos Ch. 3: 148), explains the subtle nuance and linguistic differences between the two sources. “Shekol Yeranenu B’eis HaGeulah,” that the pesukim from Tehillim are referring to the time of Redemption, when all will rejoice.
 As reported in Sefer Chut Hameshulash (pg. 128). See also sefer Tzena Malei Sifra (pg. 184; cited in Rabbi Oberlanders ma’amar ibid. footnote 65) who records the alternate ending of the story. The Chasam Sofer himself expounded on the importance of this minhag as well - see Drashos Chasam Sofer (vol. 2, pg. 285, 3rd column; newer version vol. 2 pg. 576, Drashos L’Shavuos 5562 s.v. v’asisah).
 Chayei Adam (vol. 2, 131: 13), Chochmas Adam (89: end 1), andMaaseh Rav (195).
 Vayikra (Ch.18: verse 3).
 Rambam (Hilchos Avodah Zara Ch. 11: 1- 3), Tur and Shulchan Aruch (Yoreh Deah 17: 1), based on the Sifra (Parshas Acharei Mos, Parshata 9, Ch. 13: 8).
 Tosafos (Avodah Zarah 11a s.v. v’ee); answering the seeming contradiction between the Gemara in Avodah Zara ad loc. and Sanhedrin 52b).
 Ran (Avoda Zara 2b s.v. Yisrael), Chiddushei HaRan (Sanhedrin 52b), Shu”t Maharik (Mahar”i Kolon/ Cologne, Shoresh 88, Anaf 1), and Shu”t Rivash (vol. 1: 158 s.v. v’yesh and v’im).
 Biur HaGr”a (Yoreh Deah 178: end 7) and Gilyon Maharsha (ad loc. 1). The Gr”a is bothered by the fact that the sugya in Sanhedrin seems to imply differently than the views of the Maharik, Ran, and later, the Rema, that a Chok Goyim, even one that is not a Chok Avodah Zarah should still be prohibited. Others who ask this question and conclude tzarich iyun on the Maharik’s shittah include the Minchas Chinuch (Mitzvah 262: 2) and the Maharam Bennet (Divrei HaBris; cited in Shu”t Imrei Aish, Yoreh Deah 55). However, there are those who do resolve the Gr”a’s difficulty, such as the Maharam Shick (Shu”t Yoreh Deah 165).
 Darchei Moshe and Rema (Yoreh Deah 178: 1). Although he does not cite either side of this machlokes in his Shulchan Aruch, nevertheless, in his Beis Yosef commentary, Rav Yosef Karo elucidates the shittah of the Maharik at great length and does not even cite Tosafos. Although one may infer that the Rambam (and later the Shulchan Aruch who codified his words as halachah) actually meant similar to Tosafos’s understanding, as the implications of the prohibition of not copying actions of the Goyim, is seemingly unrelated to actions smacking of idol worship (and that is what the Ra’avad was arguing on and ruling akin to the Maharik), nonetheless, from the lashon of many other authorities, including the Maharik himself (ibid.), Sefer HaChinuch (Mitzva 262), Mabit (Kiryas Sefer on the Rambam ibid.), Meiri (Sanhedrin 52b), Bach (Yoreh Deah 178), and Divrei Chaim (Shu”t Yoreh Deah vol. 1: 30), it is clear that they understood that the Rambam himself was only referring to actions that had some relation to Avodah Zarah. See Shu”t Seridei Aish (old print vol. 3: 93; new print Yoreh Deah 39, Anaf 1: 5-14) who explains this at length. See also Shu”t Melamed L’Hoyeel (Orach Chaim 16), Shu”t Igros Moshe (Yoreh Deah vol. 4: 11), Shu”t Minchas Yitzchak (vol. 1: 29, 3 and 31), Minchas Asher (vol. 3, Vayikra, Parshas Emor, 33, pg. 197-205), and the Aderes’s recently published Ovar Orach (Shema Eliyahu, 275, pg. 271-272; 2003), who discuss the parameters of the prohibition of “U’Vichukoseihem Lo Seleichu” and its nuances at length.
 Another interesting contemporary machlokes regarding flowers is whether planting flowers around a grave, ostensibly for kavod hameis, is considered a violation of Chukos HaGoyim. On this topic, see the Rogatchover Gaon’s Shu”t Tzafnas Pane’ach (vol. 1: 74), Shu”t Minchas Elazar (vol. 4: 61, 3), Rav Dovid Tzvi Hoffman’s Shu”t Melamed L’Hoyeel (Yoreh Deah 109; also citing the opinions of Rav Samson Raphael Hirsch and Rav Ezriel Hildeseimer), Shu”t Minchas Yitzchak (vol. 1: 31), Shu”t Seridei Aish (new print, Yoreh Deah 108), Shu”t Yaskil Avdi (vol. 4, Yoreh Deah 25), and Shu”t Yabea Omer (vol. 3, Yoreh Deah 24).
 Erech Lechem L’Maharikash (Glosses to Yoreh Deah 178: 1; he adds that in his opinion we may not categorize instances not mentioned by Chazal as potential ‘Chukos HaGoyim’), Shu”t Imrei Aish (Yoreh Deah 55), Yosef Daas (Yoreh Deah 348 s.v. v’hinei), Shu”t Ksav Sofer (Yoreh Deah 175), Shu”t Maharam Schick (Yoreh Deah 351), Daas Torah (Orach Chaim 494 s.v. v’nohagin and glosses to Orchos Chaim ad loc. 8), Shu”t Mahara”tz Chiyus (6), Shu”t Seridei Aish (old print vol. 3: 93; new print Yoreh Deah 39, Anaf 2), and Shu”t Yabea Omer (vol. 3 Yoreh Deah 24: 5)
 Rav Asher Weiss, the renowned Minchas Asher, in a recent maamar on the subject (“Shetichas Asavim B’Chag HaShavuos”; available here:), adds that several Acharonim, including the Chasam Sofer (Shu”t, O.C. 159; in a teshuva to the Maharatz Chiyus) and Beis Shlomo (Shu”t Y.D. vol. 1: 197) made an important distinction – ruling that even if a custom started due to goyim (i.e. a specific style of dress), once it is common for Jews to act similarly, it can no longer be considered Chukos HaGoyim. Rav Weiss illustrates this salient point with the minhag of Kaparos. Although the BeisYosef(O.C. 605) cites the OrchosChaim(Erev Yom Kippur1) quoting the Ramban, that shluggingKaparos is considered DarcheiHa’Emori, with the Tur and Rema(ad loc.; and in DarcheiMoshe ad loc. 5) defending this practice as a kosher common one, would anyone nowadays think that Kaparos is DarcheiHa’Emori? Has anyone ever heard of a single, solitary non-Jew waving a chicken around his head on an October morning? Quite assuredly not. Hence, even if a minhag may have started out as a non-Jewish custom, it possibly may no longer be considered as such.
 Furthermore, it must be noted that the Seridei Aish (Shu”t old print vol. 3: 93; new print Yoreh Deah 39, Anaf 2) at length proves that the Gr”a’s shittah actually runs contrary to the vast majority of Rishonim who conclude that unless there is at least a ‘shemetz’ of Avodah Zarah in their actions, copying them would not be a violation of Chukos HaGoyim. See also Shu”t Bnei Banim (vol. 2: 30) who writes that the minhag ha’olam is to follow the Rema in this dispute, as even according to those who generally follow the Gr”a’s psakim, that is only when it is a machlokes Acharonim. Yet, he posits, when the Gr”a argues on both Rishonim and Acharonim, then the normative halachah does not follow his shittah. However, see Shu”t Mishnah Halachos (vol. 10: 116) who does take the Gr”a’s opinion into account (in his specific case) and seems to side with him. The Minchas Yitzchak (vol. 1: 29, 3), as well (in his specific case) implies that if all factors were equal, it would be preferable to be machmir for the Gr”a’s shittah.
 Yosef Daas (ibid.),Daas Torah (ibid.),andShu”t Rivash (ibid.). See also Rav Avrohom Menachem Halevi Steinberg, Av Beis Din of Brody’s Shu”t Machazeh Avraham (Orach Chaim 29), who concludes similarly. Interestingly, the Rivash adds that this visiting the cemetery was performed l’kavod hemeis. He rhetorically concludes that if we would prohibit this due to Chukos HaGoyim simply because non-Jews do so as well, perhaps we should proscribe all hespedim, as non-Jews also give eulogies.
 Daas Torah (ibid.), Glosses to Orchos Chaim (ibid.), andShu”t Maharsham (vol. 7: 55 s.v. u’vazeh).Conversely, Rav Moshe Feinstein zt”l (Shu”t Igros Moshe, Yoreh Deah vol. 4, 11: 5), simply refers to this sevara as ‘aino klum’. Another interesting difference between the two shittos, is that from his wording, it seems that the Maharsham (and possibly most other Acharonim) understood that the non-Jewish holiday the Vilna Gaon was referring to when the Christians decorate with trees and greenery, to be X-Mas, whereas Rav Moshe understood him to be referring to Pentecost, which occurs around Shavuos time. A potential difference between the two understandings might enable us to glean whether the Gr”a meant to argue on the Rema or not. This is because the idea of erecting trees on X-Mas was introduced by Martin Luther, ym”sh, founder of the Protestant movement, and subsequently came into widespread practice in Protestant countries. As he died in 1546, it is unlikely that the Rema, who died soon after, in Catholic Poland in 1572, had even been aware of this practice. However, the Vilna Gaon, who lived 200 years later in Lithuania, was certainly aware of this practice and therefore forbade any similar ones of ours. Accordingly, a case can be made that if the Gr”a was referencing X-Mas, then his intent was exclusively to abolish trees, and not the grasses custom observed by the Rema. Yet, the Chayei Adam (ibid.), first to mention the Gr”a’s practical opposition to the tree minhag, refers to Pentecost, calling the holiday ‘Zolonia Shventa’ and ‘Pfingshten,’ which are the Yiddish transliterations of the Polish and German names, respectively, for Pentecost, (literally meaning) 50 days after their springtime Easter holiday. As such, one may infer that the Gr”a intended to abolish all greenery, even grasses. On the other hand, the Chayei Adam himself explicitly and exclusively states trees as being problematic, with no mention of grasses being on this verboten list, implying that greenery was not an issue. Interestingly, nowadays this holiday of Pentecost does not seem to be widely celebrated or observed, which may arguably lend more reason for leniency with us decorating with trees Shavuos-time. [See footnote 45 for a similar sevara from Rav Yosef Shalom Elyashiv regarding Eretz Yisrael.] Conversely, as the Gr”a’s concerns that as our festooning on Shavuos is only a minhag, and perhaps the chashashos of prohibition should overrule them, might still be in effect, even if the similar non-Jewish practice is no longer common. Rav Asher Weiss, the renowned Minchas Asher, in a recent maamar (“Shetichas Asavim B’Chag HaShavuos”; available here:) adds that perhaps the Vilna Gaon was so machmir in this instance as the non-Jewish custom we are dealing with stems from their houses of worship. Would we want to incorporate into our heilige shuls and Batei Midrash any practice that shares even a smidgeon of similarity to idolatrous practice? He further notes that when Reform (Neolog) first started, they sought to incorporate the tzurah of Church service into shuls (with some starting with an organ, etc.) and Gedolei Yisrael waged a holy war against even the smallest of these “innovations.” Perhaps this is why the Vilna Gaon deemed it preferable to rather abolish the minhag altogether. On the other hand, practically, as compelling as these various and differing rationales are, there does not seem to be a clear-cut consensus among authorities as to any one of them being considered the most accurate.
 Otzar Hachaim (Parshas Kedoshim, Mitzvah 263). Interestingly, even so, the Kamarna minhag (Minhagei Kamarna (Shavuos, pg. 80: 359) is not to adorn the shul with trees, flowers, or grass. Several other Chassiduses, including Munkacs and Chabad so as well. Even though they defend the minhag, they personally do not actually observe it.
 Gemara Bava Kamma (83a) and Sota (49b), Rambam (Hilchos Avodah Zarah Ch. 11: 3), Tur and Shulchan Aruch (Yoreh Deah 178: 2).
 This was the understanding of the Sefer HaLikutim, a talmid of the Gra”s, cited in the Likutei HaGr”a commentary on sefer Maaseh Rav (ibid.), who explicitly writes that the Vilna Gaon’s intention was to abolish the Rema’s minhag. He cites proof to this view from Rashi’s commentary to Parshas Shoftim (Devarim Ch. 16: 22), who explains that setting up Matzeivos is currently prohibited even though the Avos did so, as it was a custom that was ‘hijacked’ for idolatrous practice. He concludes positing that perhaps in the days of the Rema the non-Jews did not festoon their houses of worship with grasses or trees. Similarly, in the Shivim Temarim commentary on Tzavo’as Rav Yehuda HaChassid (end 4) it mentions that the Vilna Gaon was actively mevattel all greenery minhagim on Shavuos, even though it was practiced by earlier authorities.
 Chayei Adam and Chochmas Adam (ibid.), Mishnah Berurah (Orach Chaim 494: end 10) and Aruch Hashulchan (ad loc. end 6).
 As per the Rema and the early Ashkenazic authorities who first cited the minhag, as listed in footnote 2. See also Minhagei Yeshurun (131), Otzar Kol Minhagei Yeshurun (Ch. 61: 2, Shavuos, pg. 196), and Kovetz Yerushaseinu’s annual Luach Minhagei Beis Knesses L’Bnei Ashkenaz (Sivan, s.v. asavim v’ilanos; from Rav Binyomin Hamburger’s Machon Moreshes Ashkenaz). See also the recently published Minhagei Maharitz Halevi (pg. 195-196), who gives an extensive list of sifrei Kehillos Ashkenaz who describe performing the minhag of festooning the shul with foliage.
 Aside for the aforementioned Shulchan Aruch HaRav, Bnei Yisaschar, Shaar Yissachar, and hanhagah of the Chasam Sofer, see sefer Zichron Yehuda (hanhagos of the Maharam Ash; pg. 34b, 159), Imrei Pinchas (312), Mei Hashiloach (vol. 1, Likutim, pg. 279; regarding pictures of flowers on the shul windows), Sfas Emes (ibid.), Shu”t Siach Yitzchak (237), Migdal Dovid (Lekutim Yekarim pg. 44), Tiferes Yaakov (Hanhagos of the Maharam Bennet; pg. 24), Shu”t Hisorerus Teshuvah (vol. 4, pg. 74 s.v. sham s.k. 5), She’aris Moshe (ibid.), Lekutei Mahariach (Minhag Erev Chag HaShavuos s.v. v’hinei), Yalkut HaGershuni (Orach Chaim 494: 3), Taamei HaMinhagim (617), Shnos Chaim (Ch. 20: 2), Netei Gavriel (Hilchos Chag HaShavuos Ch. 9: 1 and footnote 2), Piskei Teshuvos (494: 10), Minhag Yisrael Torah (Orach Chaim vol. 2, pg. 601), Rabbi Gedalyah Oberlander’s ma’amar in Kovetz Ohr Yisrael (Sivan 5760; vol. 20, pg. 148 - 149), and Kovetz M’Beis Levi (on Nissan, Iyar, and Sivan; Nissan 5766; Chodesh Sivan, Erev Yom Tov, pg. 81 and footnote 2 ad loc.; who only adds the Gr”a’s shittah parenthetically and not as the ikar minhag).
 Minhagei HaBeis Aharon M’Karlin (pg. 8).
Belz Devar Yom B’Yomo Luach (5776; pg. 602) and sefer Minhagei Belz (pg. 46).
 Shefa Chaim Kuntress L’Shavuos (cited in Netei Gavriel ibid. footnote 17).
 Spinka Tefillas Yitzchak Siddur (pg. 35, ‘Minhagei Spinka’). See also Toras Hametzaref (Parshas Balak, pg. 208 s.v. nireh) who cites an additional reason for the minhag of spreading grasses that he records that he told over to the Spinka Rebbe, adding that the Rebbe was mekabel.
 Skver Luach Maagalei Hashanah (5 Sivan, Erev Chag HaShavuos).
 Cited in Netei Gavriel (ibid.) and Kovetz Ohr Yisrael (ibid.).
 Cited in Orchos Rabbeinu (vol. 2, pg. 99; in 5775 edition vol. 2, pg. 118: 8 and 9). The Chazon Ish is cited as personally not doing any green decorating, but nevertheless allowing his shul’s gabbai to use grasses and flowers.
 Cited in V’aleihu Lo Yibol (vol. 1, pg. 184: 289) and Shalmei Moed (Shavuos, pg. 459), and heavily implied in Halichos Shlomo (Moadim vol. 2, Ch. 12: 1, Chag HaShavuos pg. 371).
 Cited in Hilchos Chag B’Chag (Sefiras HaOmer V’Chag HaShavuos, Ch. 8, footnote 24) and Ashrei HaIsh (Orach Chaim vol. 3, Moadim Ch. 66: 1). Rav Elyashiv held that certainly in Eretz Yisrael, with the non-Jews being prominently Muslim, who do not festoon their houses of worship with trees or grass, one would not have to be choshesh for the machmir understanding of the Gr”a’s opinion. Accordingly, one may indeed decorate their shuls with flowers and grasses. Indeed, it is recorded (Sefer Hanhagos Rabbeinu, pg. 249: 41) that in Rav Elyashiv’s famed Tiferes Bachurim Caravan-Shul, “nahagu lishtoch asavim.” Rav Avigdor Nebenzahl (Yerushalayim B’Moadeha on Shavuos, pg. 184) cites similar logic as Rav Elyashiv, and rules correspondingly.
 Halichos Even Yisrael (Moadim vol 1, Erev Shavuos, pg. 223: 3 and footnote 3).
 This author was told similarly by Rav Ephraim Landy, Mara D’Asra of Beis Knesses Aderes Eliyahu in Givat Zev, who is a direct descendent of the Vilna Gaon. Interestingly, the Aderes, in his recently published Ovar Orach (Shema Eliyahu, 275, pg. 272; 2003) regarding the issue of Chukos HaGoyim and smoking on Tisha B’Av, adds as an aside that the Gr”a abolished the minhag of trees on Shavuos. Similarly, as a side point in his teshuva regarding whether the adorning foliage becomes muktzah or not on Yom Tov, and hence its permissibility as to whether or not it may be moved over Shavuos, Rav Yitzchak Isaac Liebes (Shu”t Beis Avi, vol. 4: 103, 4-5) mentions that “uv’harbeh Medinos B’Europe hayah nahug kein lehaamid Ilanos,” and that that was the minhag that the Gr”a wished to abolish. For more on the topic of whether the foliage may be moved, see Magen Avraham (O.C. 494: 4), Mishnah Berurah (ad loc. 9), and on a more contemporary note, Shu”t B’tzeil HaChochmah (vol. 4: 87 and vol. 5: 119).
 Shu”t Igros Moshe (Yoreh Deah vol. 4, 11: 5).
 Rav Chaim is quoted as holding this way in the weekly Divrei Sia”ch (vol. 230-232; Shavuos 5775; pg. 3, Question 5), that according to the Vilna Gaon, it would even be prohibited to decorate with flowers and grasses. On the other hand, and quite interestingly, in Shoneh Halachos (vol. 3, 494: 4 and 5) he seems to be agreeing with the Mishnah Berurah’s understanding. Additionally, and as mentioned previously, Orchos Rabbeinu (ibid.; see footnote 41) cites Rav Chaim’s father, the Steipler Gaon, and uncle, the Chazon Ish as understanding the Gr”a’ s prohibition as only applying to trees. When I questioned Rav Yitzchok Goldshtoff, the editor of said Parsha sheet, he replied that upon my inquiring, he later discussed this enigmatic matter with several main talmidim of Rav Chaim and together came up with two possible solutions to this seeming contradiction. One is that in Shoneh Halachos, Rav Chaim was simply citing the Mishnah Berurah’s understanding, yet his personal opinion is that one should be choshesh for the Aruch Hashulchan’s understanding of the Gr”a’s position, and not decorate with grasses either. Alternatively, he personally holds that the common minhag is not to decorate even with grasses and flowers, although the Vilna Gaon possibly only opposed actual trees. In the recently published Moadei HaGra”ch (vol. 2, pg. 115: 248) Rav Chaim is quoted as maintaining that even regarding ‘shetichas asavim b’Shavuos,’ “lo nahug etzleinu.”
 See the Luach Hahalachos V’Haminhagim shel Kehillos Ashkenazim (Perushim) Uv’Yeshivos B’Eretz Yisrael (5782; pg. 269, footnote 15), as well as Hilchos Chag B’Chag (Sefiras HaOmer V’Chag HaShavuos, Ch. 8, end footnote 24) both of whom, after listing the basic machlokes involved, ending with the Aruch Hashulchan’s understanding of the Gr”a’s proscription, conclude ‘v’chein nahagu b’Yeshivos’. Anecdotally, and quite fascinatingly, in the introduction to Shu”t Igros Moshe vol. 8 (pg. 6, s.v. Rebbi Dovid), it states that Rav Moshe Feinstein zt”l recalled that in his youth, the bochurim from the Volozhin Yeshiva would take down the trees placed in shul l’kavod Shavuos, causing an annual brouhaha. Obviously this generality is not exclusive, as there are Yeshivos that do decorate their Beis Midrash for Shavuos, for example Torah V’Daas, which uses grasses and flowers, but not trees.
 See Shu”t Mishnah Halachos (vol. 8: 107 s.v. ha’amnam), Shu”t Bnei Banim (vol. 1: 6 pg. 22, and Ma’amar 1: 10-13, pg. 209 and vol. 2: 8), Kovetz Yeshurun (vol. 20, Nissan 5768, ‘Yosef Chein - Mara D’Asra shel America’, pg. 159), and the ‘Ohr Eliyahu’ introduction to the recently published Shu”t Gevuros Eliyahu (vol. 1 - Orach Chaim, pg. 5).
 See also Halichos Shlomo (Moadim vol. 2, Ch. 12, footnote 2) which after stating the various minhagim, and concluding with the Aruch Hashulchan’s understanding of the Vilna Gaon - that he abolished all foliage adorning, adds “v’chein minhag Kehillos HaPerushim.”
 Although the Shulchan Aruch HaRav (Orach Chaim 494: 14 and 15) supported this minhag, on the other hand, sefer Minhagei Chabad (Chag HaShavuos 7, pg. 293) details at length that it is not commonly practiced. Indeed, both the Netei Gavriel (ibid. footnote 4) and Rabbi Oberlander (Kovetz Ohr Yisrael ibid. footnote 89) cite firsthand testimony that it is not currently done in Chabad circles. On the other hand, noted Chabad Chassid and acclaimed author ofShiurei Torah, Rav Avraham Chaim Na’eh zt”l (Shnos Chaim Ch. 20: 2), wrote that the prevailing minhag is to decorate with grasses, flowers, and trees.
 See Otzar Chaim (Parshas Kedoshim, Mitzvah 263) as compared to Minhagei Kamarna (Shavuos, pg. 80: 359).
 See Shaar Yissachar (Maamar Chag HaBikkurim 48) and Darkei Chaim V’Shalom (737), who although strongly defend the practice, nevertheless conclude that it is no longer ‘minhageinu,’ nor of “Kehillos Chassidim V’Anshei Maaseh,” due to the opposition of the Gr”a, explaining that festooning is not m’dina and is now considered “chok ha’amim.”
 This minhag is also noticeably absent from the recently published work of the Sefardic Av Beis Din of Yerushalayim before 350 years, Rav Yitzchak Bu’ino’s Shulchan Melachim, even though he mentions (Orach Chaim 494: 3 and 5) the two other famous Shavuos minhagim mentioned by the Rema, eating milchigs and staying up all night learning. In fact, there are several Sefardic authorities, including the Arichas Shulchan (Yalkut Chaim vol. 6, 494: 12) and the Shtilei Zeisim (494 Saviv L’Shilchanecha 3), who expressly write that festooning with greenery is not a Sefardic minhag. The Netei Gavriel (ibid. end footnote 4) writes similarly, “V’haSefardim ain nohagim klal l’haamid ilanos v’asavim,” albeit without citing sources. See also next few footnotes.
 See Knesses Hagedolah (Hagahos on Tur, Orach Chaim 494: 2), Shulchan Gavoah (ad loc. 6), Birkei Yosef (ad loc. 6),Moreh B’Eztzba (Avodas Hakodesh, Chodesh Sivan 224, Etzba Ketana), Rav Yitzchak Lapronati of Italy’sPachad Yitzchak (Os Shin, erech Shavuos pg. 37a),Rav Avraham Kalfonof Tripoli’sLeket Hakatzir (Hilchos Shavuos 10), Rav Yosef of Salonika’s Beis Dovid (vol. 1, pg. 77a, 293), Rav Chaim Pala’ji’s Ruach Chaim (O.C. 494: 4), Yefeh L’Lev (vol. 2, ad loc. 7), and Kaf Hachaim (O.C. 494: 53-59).
 Shu”t Yechaveh Daas (vol. 4: 33) and Chazon Ovadiah on Hilchos Yom Tov (Hilchos Chag HaShavuos 11, pg. 317-318). His son, the current Chief Rabbi of Israel, Rav Yitzchak Yosef, expresses similar sentiments in his Yalkut Yosef (Kitzur Shulchan Aruch, 494: 17). This minhag is also cited by Rav Raphael Baruch Toledano zt”l, in his Kitzur Shulchan Aruch (332: 31 and 32), discussing the greenery minhag but without mention of trees, the same lashon as the earlier Knesses Hagedolah. Similarly, and more recently, Rav Yaakov Moshe Hillel, in his comprehensive Luach Dinim U’Minhagim Ahavat Shalom (5778; English edition, Chag HaShavuos, Minhagei HaChag, pg. 736) wrote that “some customarily decorate the synagogue and houses with flowers and foliage,” implying that nowadays it is a common Sefardic minhag. However, in footnote 155, he adds that “the Gr”a annulled this custom, because nowadays gentiles erect trees on their holidays.” He concludes that Rav Yosef Schwartz, author of Tevuos Ha’aretz, similarly wrote (printed in Kovetz Zechor L’Avraham, 5756; pg. 582) that Sefardim in Eretz Yisrael “do not customarily place flowers in the synagogue.” It emerges that according to Rav Ovadiah Yosef, Sefardim may even festoon the shul with trees, but according to Rav Raphael Baruch Toledano and Rav Yaakov Hillel Sefardim should only use grasses and flowers if they decide to do some festooning, which it seems is not considered a true Sefardic minhag. An interesting dichotomy within a dichotomy.
 For early uses of this and similar dictums, see Tosafos (Menachos 20b s.v. nifsal), Beis Yosef (Orach Chaim 128: 7 and Yoreh Deah 39; citing the Rashba), Rema (Yoreh Deah 376: 4; citing the Maharil), and Matteh Efraim (610: end 11).
Disclaimer: This is not a comprehensive guide, rather a brief summary to raise awareness of the issues. In any real case one should ask a competent Halachic authority.
L'iluy Nishmas the Rosh HaYeshiva - Rav Chonoh Menachem Mendel ben R' Yechezkel Shraga, Rav Yaakov Yeshaya ben R' Boruch Yehuda.