On the third day of creation, we are told that the Holy One Blessed be He created the herbs, vegetation and fruit trees. Later on, (Bereshith 2:5) the Torah states: "The shrubs of the field were not yet on the earth and the herbs of the field had not yet sprung up".
Rashi comments and explains, based on the Gemara of Hullin, that even though the trees, the shrubs, the herbs and all vegetation were created, their process of growth came to a halt. They all remained beneath the surface of the earth, waiting to break through.
What were all the trees, shrubs and herbs waiting for? Why hadn't they all appeared above the ground?
"And there was no man to work the ground". Hashem was waiting for the prayer of Adam!
Only when he prayed for rain and acknowledged the fact that the actual growth of the vegetation is dependent on the Al-Mighty, did it had happen. Moreover, even though the gift of the fruit trees, the grass and the flowers was right there, it only broke through and became part of Adam's world, after he had asked for it.
The great sage, Hakham Yoseph Hayim, 'a"h, expounds on this thought and poses the following question: Doesn't the Al-Mighty know what our needs are and even better than we do? Why, then, do we need to pray?
We need to create vessels, he explains, to "hold" the blessings and the abudance that He wants to bestow upon us. When a poor person asks for food, he must bring a vessel with him to place the food in it. The letters of the words of our Tefilloth have the power of creating such vessels and pipes through which an abundance of good will flow. This clarifies why the Holy One Blessed be He desires the prayers of the righteous!
Let us pray, pray and pray.