The Bavli Talmud, Rosh Hashana, 11:71 -- Rabbu Joshua says: How do we know that the world was created in Nissan? Because it says, And the earth brought forth grass, herb yielding seed after its kind, and tree bearing fruit. Which is the month in which the earth is full of grass and trees and starts to produce fruit? You must say that this is Nissan. 

 

For one who travels through the Land of Israel during this time of year by foot or even by car – the eye tires of the sights of abundance of flowers in every corner, like a huge colourful rug placed over Israel from the north to the Negev and from the coast to the East, mountain and gorge, hill and valley immersed in a diverse abundance of all the colours of the rainbow. There is a festival for the flora in Israel during this time of year. Spring encompassing the meaning of the word. However, one who is looking with open eyes at the sea of flowers before him will feel that in this remote area, on the edges of the spotted sheet, the withering is slowly sneaking in, and here and there the bald spots are appearing. It seems that by intention and knowledge, it would seem, the abundance of the flowering is concentrated into a short and limited time period, because now the rain is passing and the sun is coming out of its pouch. The influence of the east is overcoming day by day the influence of the west. The period of the rains, which is fighting a tough war on a daily basis and did not waver in its service – has at last surrendered to the days of the sun and has departed. On the horizon the mist of the hamsin is rising and the gust of its breath breaks out and passes the Jordan and turns westward and following it – the withering and the wilting. Here the leaves of the squill and the chives are yellowing and are drying out before us in the area of the colourful and refreshing pit  In the field the crops are rising and all the material is stained by the mandrakes and they start to give off their strong scent. The grass is green and refreshing – suddenly it has another face. And it bows its head. In the area of the pit numerous seeds appear of many of the winter annual plants, and in the soft and gentle landscape the various “nettles” suddenly grow and take over with their barbs and their chutzpah, throwing out their prickles instead of flowers.