There is a lovely old minhag (tradition) that connects Tu B'shvat to weddings. But before I discuss this connection, I guess I should first explain a bit about Tu B'shvat.
First of all, Tu B'shvat is the 15th of the month of Shvat (usually celebrated somewhere around January/February) and marks the New Year for the trees. A year in the life of a tree is reckoned from one Tu B'shvat to the next year's Tu B'shvat. Tu B'shvat heralds the very beginning of spring in Israel; when the earliest of the trees begin to bloom and a new fruit-bearing cycle begins.
One of Israel's best-known children's Tu B'shvat songs "The Almond Tree Blooms" "השקדיה פורחת")), (lyrics by Yisrael Duchman), says (loose translation): "The almond tree blooms and the sun shines… Tu B'shvat is here, A holiday for the trees…".
It may still be cold and rainy in Israel, but somehow you know that spring is just peeking around the corner. This is a day when school children all over Israel plant trees. Tu B'shvat is celebrated all over the world, usually by eating a new fruit (one that has not been eaten since last year) or fruits, such as figs and dates, which grow in Israel. Many people make a se'uda (a festive meal) and even use a Tu B'shvat Seder Plate, reminiscent of the Pesach Seder plate and place on it a selection of the fruits of Israel. For more information you can read these sources and many others:
I have this vivid memory when I was a kid growing up in the Bronx and I had to get Bukzar (carob) for a Tu B'shvat celebration in school. I remember trudging through the snow with my mother and I remember thinking: how is it possible that this is the beginning of spring? But when you live in Israel, the holidays and the timing of the holidays make sense!
Now, what is the connection between Tu B'shvat and a chuppah? It says in the Torah (D'varim 20:19) that "…a man is a tree in a field" ((כי האדם עץ השדה. The symbolism is very significant on a number of levels. Many halachot surround the planting and growing of trees, as well as the harvesting of the fruit of these trees. Many minhagim have grown from these halachot, a famous example of this is the minhag of not cutting a baby boy's hair until he is three, just as we do not eat the fruit of a tree until its third year of producing fruit.
There is a very old minhag that the parents of a new born child planted a tree in his/her honor. A cedar tree was planted for a baby boy and a pine tree was planted for a baby girl.
When a couple married, branches from "their" trees where cut and joined together to create the chuppah. Thus this chuppah helps join the couple in marriage and while it creates the bond between a man and woman, it also helps create a stronger bond between the couple and the trees and the Land of Israel.