Why did the ancients have the custom of hanging flower protection banners in February of the lunar calendar?

The Flower Festival on February 12th of the lunar calendar is the birthday story of Baihua:

According to "Broad Spectrum", the customs of Flower Festival have existed in Chang 'an and Luoyang in the Tang Dynasty. "Boyi Collection" and "Zhenyang County Records" also provide a beautiful legend for its origin:

During the Tianbao period of the Tang Dynasty, there was a flower fan named Cui Xuanwei, who was well known. On the night of February, a group of gorgeous women transformed by Hua Jing entered their garden and told him that they wanted to meet the blooming spring, but they were in the way of their aunt (Fengshen), so they asked him to help them solve their problems. Cui Shi listened to his advice, prepared colorful silk and drew the sun, moon and stars on it. February 2 1 day (1 month 12), at 5 o'clock, he will

Jia Qinglu recorded that February 12 was the birthday of Baihua, and the Huqiu Flower Temple offered sacrifices to wish the immortals a birthday, which was called "Flower Dynasty".

It is a good time to record Baihua's birthday in Wu Biao. Before the mid-flowering period, the eyes were full of colorful flowers, and they were still struggling to decorate the flower god.

"Qing Ji Chao" also records the account of Empress Dowager Cixi who cut the ribbon and tied flowers in the Summer Palace on the "Flower Festival" and watched the "Flower God's Birthday Celebration". As for who is the flower god, there are different opinions.

The traditional flower show has now become a more dazzling seasonal flower show, and the trend of mass flower viewing often lasts for several months, far exceeding the ancient one-day period. However, if we trace back to the origin of this traditional custom, it is ambiguous.