When will there be catkins?

It should be around the vernal equinox in April, maybe a little earlier, because willow is a plant that germinates earlier.

There is a poem to prove it: Zheng Chouyu's Jiangnan.

I walked through Jiangnan.

The appearance in the season is like the opening and falling of lotus flowers.

The east wind won't come.

The catkins in March can't fly

Your heart is like a small window.

.........