1,195. How to Perform the Mitzvah of Lulav

Hilchos Shofar, Succah v’Lulav 7:6

The best way to perform the mitzvah is to bind the lulav, myrtle and willow together, making a single unit of these three species. Before taking them to perform the mitzvah, one recites the bracha on taking the lulav, the other species being dependent on it. One then takes this bound unit in his right hand and the esrog in his left hand. One must take the species as they grow, with their roots on the bottom towards the ground and their tops above towards the sky. If one did not bind the lulav, myrtle and willow together, but took them individually instead, he still fulfills his obligation so long as he used all four species. If one has only one species or is lacking one species, he may not take them until he acquires the ones that he is missing.

Hilchos Shofar, Succah v’Lulav 7:7

One takes one lulav, one esrog, two willow branches and three myrtle branches. If one wants to add more myrtle branches to increase the size of the bundle, he may do so. In fact, doing so is considered to be an enhancement of the mitzvah. One is not permitted to add to or detract from the number of the other species. If one does so, it is not valid.