During the diaspora, Tu Bishvat was being forgotten. In the 16th century, Kabbalists [mystics] in tzfat gave the holiday new relavence by popularizing the Seder Tu Bishvat . The Tu Bishvat seder is loosely based on the Pesach seder. Similar to the Pesach [Passover] seder, there are four glasses of wine at a Tu Bishvat seder. Unlike Pesach, at this seder, the color of the wine for each drinking is varied. The first cup is all white wine; the second is mostly white mixed with some red; the third is mostly red mixed with some white; and the fourth is all red wine. One can substitute blush and rose for the middle two cups of wine because these have the intermediate colors already.
Customs vary on the Tu Bishvat seder, according to tradition, with some stressing dried fruit, some Fruits from Israel. Giving a gift of fruit from Israel has become a traditional way of honoring this tradition.