The Laws of Shavuos

Erev Shavuos

1. Even for those who keep the second part of Sefirah and therefore do not take a haircut after Lag Ba'omer; one is permitted to take a haircut during the "Shloshes Yimay Hagbalah" - the three days before Shavuos.

Starting Shavuos
1. On Shavuos at night the minhag is to wait until it is night (Tzeis Hakochavim) to daven Maariv in order to have 49 complete days.
2. Likewise, it is preferable for women to wait until it is night to light candles and say Shehechiyanu on Shavuos night.
(if lighting after nightfall, some say the blessing before lighting; others say it after; but always use a flame lit from before sundown!)

Staying Up All Night
1. There is a minhag cited in the Zohar to stay up the night of Shavuos and learn Torah. This is based on the Midrash which says that Klal Yisroel slept the night before Matan Torah and Hashem had to awaken them to receive the Torah. Therefore we stay up all night to rectify their oversight.
2. The Ari'zal writes that one who does not sleep the night of Shavuos and toils in Torah is assured to live out the year and no damage will occur to him.
3. There is a compilation of torah learning known as "Tikkun Leyl Shavuos" which has The Zohar and the writings of The Ari'zal as it's source, and many have the minhag to say/learn this on Shavuos night.
4. Generally women should not say the "Tikkun Lely Shavuos". However, some say that a woman who counted all the days of Sefiras Ha'omer may learn the portions of the Tikkun which are from Tanach.

Brachos in the Morning
1. Staying awake all night of Shavuos makes morning blessings ('birchos hashachar') very tricky. There are many different opinions and customs. One should follow their own custom and/or consult with a rabbi.
2. One who stayed awake all night should immediately, at Alos Hashachar, use the restroom, wash one's hands for Netilas Yadayim, then make the berachos of "al netilas yadayim" and "asher yotzar". Or one may listen with the intent to fulfill the obligation of these two blessings from someone who had slept the previous night.
3. One should listen to Birchas Hatorah with the intent to fulfill the obligation of this blessing from someone who slept before one continues to learn. This should be followed by each person reciting 'yevorechecha' and 'eilu devarim' so that the blessings are followed immediately by some Torah learning. Then, during the blessing 'ahavah rabba' one should have the intention to fulfil the obligation of this blessing (Otherwise, one may sleep at least a half an hour during the day of Erev Shavuos OR one may stipulate while reciting the blessing on Erev Shavuos that this blessing should be in effect only until the next morning and then one may recite the blessing on Shavuos morning.)$
4. One who stayed awake all night should listen to the berachos of "Elokai Neshama" and "Hamaveir Shayna Mayeinoi" from someone who slept during the night. If one didn't, one may still recite them.
5. One who stayed awake all night should not make a beracha on his tzitzis. Rather, he should make the beracha on his Tallis Gadol and have in mind to be yotze for his tzitzis with the same beracha.
6. Even though one may recite all the other morning blessings after having stayed awake all night, most synagogues have a custom that one who slept recites all twenty morning blessings for the benefit of all those who did not sleep.
(The sixteen blessings which may be recited by each individual should not be heard from another person unless a minyan is present. This is since some poskim hold that the obligation of Birchos ha-shachar is discharged only by hearing them from another person in the presence of a minyan)

Eating on Shavuos
1. Many have the minhag to eat a dairy meal (and milk and honey) on Shavuos. Some eat dairy at night and meat at the day meal, while others eat dairy, bentch, and then wash again, and eat meat to fulfill Simchas Yom Tov with meat.
2. If one eats dairy, but not "hard cheese" (which requires one to wait six hours before eating meat) one need not bentch and wash again. However, one should wash his /her mouth well, eat something hard like bread and the tablecloth should be changed. (Other poskim require one to bentch).
3. One should be careful not to use leftover challah from a dairy meal at a meat meal. (This is applicable all year as well). Rather, one should use new challahs for each meal. This also fulfills the minhag of rememberance of the Shtei Halachem (Two Loaves) brought on Shavuos in the Beis Hamikdash.

Other Laws & Customs
1. We read Megillas Rus on Shavuos because it was written to document the yichus of Dovid Hamelech and Dovid Hamelech was born and niftar on Shavuos.
2. One should refrain from marital obligations on the night of Shavuos unless it is the Leyl Tevilah or if one was has not yet had children (one boy and one girl).

3. One who goes to sleep after Alos Hashachar does not say the beracha of Hamapil.
4. There is a well known minhag to bring flowers into the shul and home as a remembrance that on Shavuos we are judged on "Peiros Ha'ilon" - fruits. However, one should not cut off branches from fruit bearing trees for this purpose inasmuch as some poskim do not permit this because of the Torah prohibition of "Ba'al Tashchis".
5. Those who follow the minhag of the Gr'a (Vilna Gaon) do not place flowers in the shul. The Gr'a ended the minhag because it had become the custom of non-jews to decorate their places of worship with flowers.

6. There is a not so well known minhag to bring good smelling grasses into shul to be passed around for people to make a beracha and smell the grass in remembrance of the Simcha of Mattan Torah where Har Sinai was surrounded by grass.
7. When practicing this minhag one should not pass the grass during davening between Boruch She'amar and kaddish after Sh'mona Esrei because one is not permitted to interrupt davening at that time to make the beracha.

8. From Rosh Chodesh Sivan until the 8th of Sivan (Isru Chag) we do not say Tachnun. Some do not say Tachnun until the 12th of Sivan (inclusive), and in the Diaspora until the 13th of Sivan (inclusive).