You might have read in the Destination of the Week piece on Petah Tikvah that the original land for the settlement was purchased on Tu B’Av, an unimportant holiday which nonetheless has a long history.
The original significance of Tu B’Av dates back to the days of the Temple in Jerusalem as the festival marking the start of the grape harvest which ended on Yom Kippur. One of the highlights of the festival was the appearance of unmarried girls dressed in white who would then dance in the vineyards. The Babylonian Talmud (tractate Ta’anit 30b - 31a} asserts that Tu B’Av and Yom Kippur were the happiest of all the holy days.
Another tradition holds that female orphans without brothers were not allowed to marry outside their tribe in order to preserve inherited property within the tribe. This custom was suspended for the day of Tu B’Av with tribal intermarriage allowed. The significance of this custom found its way into Christian tradition and by the 4th century CE, was being celebrated as Valentine's Day, on which unmarried females were able to choose a marriage partner without parental intercession.
The modern era has seen Tu B’Av become a favoured day for Jewish weddings with the bride and groom not having to fast if their wedding is celebrated on that day. Tu B’Av is often described as a day for romance, explored through singing, dancing and giving of flowers. These traditions have led to many claiming that the romantic undertones of the day are a Jewish clone of Valentines Day, while the exact opposite is the case.