You mulch perennials in hope that if they do freeze back that the buds will be protected and can come out in the spring. Agaves only have that one central growth point. My advice would be to wrap the central point with Insulate .

Uh oh, I wish I had known that before our freeze.

A rock mulch would be better, but it won't solve your problem.. It takes awhile for agaves to reach their final rate of hardiness. They are always tender the first couple of years. I would cover the whole thing with a floating row cover when one gets the freezes, especially the really big bad ones. How did it go through this last freeze. AND here is the bad news, Agave americana is very borderline for the Dallas area, I think. I am not from the area, but I would think it would have a tougher time. Many bit the dust here in the Austin area, especially any with variegation .

I would really recommend if there is a next time, Agave Ovatifolia. It is both Heat, water, sun, cold and cold wet tolerant. This agave is bullet proof and knock dead gorgeous. I have a clay tolerant A proto-Americana and a Dark green A. Salmiana-ferox that is bullet proof also. Other varieties that have been long time success stories for me are the Agave lophantha, Agave striata, A. lechugia. I would like to get a Agave scabra. They are much hardier also.

About Agaves developing cold hardiness over a year, I planted a A. horrida ssp perotensis .Plant Delights says 7b but SMgrowers says 20-25F. Yuccadoo says 8b. Now I am confused. Last winter it got damaged at 28 and severely damaged by the end of the winter and it was well covered. I came with in a hair of yanking it out but the core was still good and the athracnose secondary infection seemed to stop progressing.It is looking good after one year of growth and headed into the next winter. A temperature gage measured 25F, under a tree not far from it during the last cold front. and it shows absolutely no damage from 2 nights drop to 25. and I didn't cover it. I covered it last year after the first damage at 28. So this year it has proven much hardier. So far , so good. Here's to hoping.
Your little guys and newly planted need protecting.

I would check other sources for hardiness temps. Everyone is making it up as they go. And there is a great difference of opinion. It is so dependent on soil , rain, the length of the shot of cold , do plants get a hardening off period, planting conditions, that it is just hard to make generalizations. ALWAYS address the drainage issues.

Here is a link that might be useful: Agave hardiness list

Thanks!

Hi Sylvia, I just stumbled across this post. I too am in the Dallas area and am about to plant some blue agaves. How did the mulch do? Did it mold or cause any problems?

Hi, Joel! Short answer is, I don't know LOL. Those things grew so fast that they were about to take over the universe. I gave them to someone who had a bigger yard and no trees.