A Kiruv organization that has an established well attended and successful shiur on Monday nights want to make a Tu Bishvat special party and Seuda on Monday night (year 2023) and make a Seder on eating the fruits that usually has a great response. The problem is that this year Tu Bishvat is Monday and the shiur is usually at night, when it is already the day after. Is there any way one may extend the day of Tu Bishvat to the night after as one does with Shabbat or Yom Tov and comply then with the tradition of eating the fruits?

Although when we deal with Shabbos or Yom Tov, the Kedusha of the day can be extended in some ways after the Halacha dictates the end of the day and even after Havdalah can be recited, even until close to midnight if you leave enough time, for praying Maariv and eating the Melaveh Malkah Seudah. However, for most other purposes, the day does not necessarily extend after the night sets in. It would seem that the same applies to Tu Bishvat, so there would be no purpose or sense to have during the night after a Seuda honoring Tu Bishvat, eating the fruits and reciting the Tefilos and brochos of that meaningful day after the day has ended. However some suggestions and solutions have been mentioned. Some mentioned that at least in principle, when dealing with Kodshim, and the Beis Hamikdosh sacrifices, the night follows the day, so in a sense, since the fruits eaten during Tu Bishvat could be appreciated (as they are by some Chassidim sources) as being sacrifices to Hashem, then the night after would follow the day. Another solution would be, to start the Seuda before sunset and then continue the meal after nightfall and daven Maariv after the end of the Seuda.