Hello, Donna, They will fall off when ripe. Ours usually turn yellowish-green when they fall off. We have begun picking up the ripe limes this past week, and must have a couple of hundred on the tree right now, which will ripen between now and December. A few strays will ripen in January and February. The limes peter out just as the mandarins are coming in, followed by the navels and blood oranges. Ron Van Nuys, CA