What kind of drainage do you have in the planter. These babies need absolute drainage and soil that will dry out. I would think a 6 inch layer of coarse gravel on the bottom of the planter, cover the drainage holes with plastic screening.

then mix the cactus mix you used with pumice at 1 part cactus mix to 2 parts pumice. Even decomposed granite available at landscaping supply stores would be great for the species. Water no more than once a week. It enjoys full sun in a warm spot.

Hi Katie,

Actually your agave is a century plant or agave americana marginata. I am attaching an article from the University of Arizona Master Gardener/ Agricultural articles which may help you. Do you know how old it is?

http://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1399.pdf

Thanks! Deana Bella Fiore Landscape Design

I had one of these Agave and it started to do the same,then eventually died, when I removed it found that some type of borer beetle had burrowed thru the base above the roots and killed it.Holes were actually quite large but not visible because of where they were. I was upset to lose it.

Just read the UofA article and it looks like it was the Agave Snout Weevil that did mine in! Thank you BellaFioreLandscape Design for your input.