Ask Mr. Smarty Plants

No, no, no, don't kill it. You are about to be blessed with blooms, and it sounds like a bunch of them, all at once. That's the good news. The bad news is that agaves, often referred to as "Century Plants" only manage to develop the resources to bloom once in their lives, and then they die. If you cut off the budding blooms, we're not sure what will happen, but we'd be willing to bet the agave will still die, as it has put all of its energy into flowering, which leads to seeds, which leads to reproduction, which is why all living organisms exist, to reproduce themselves.

You didn't say which agave you had, but we have picked two, Agave havardiana (Havard's century plant) and Agave parryi (Parry's agave), links on which you will find some basic information about the species. Also, a couple of pictures may help you visualize what is going on. It takes anywhere from 8 to 40 years for an agave to bloom (not really a century), and it's considered quite an event when one does make it. Once it has bloomed, the bloom stalk will dry and the plant itself will begin to shrivel and turn dark. At whatever time it becomes unattractive, you might as well remove it from your garden-carefully, the thorns are the last thing to shrivel. You probably have had some "pups", small agaves, develop around the parent plant. If you wish to continue the agaves, these pups will now become the ones that will produce blooms for the next generation of gardeners.