This past winter, I decided to let all of my in-ground plants (except my 20 year old Sagos) & most of my potted Agaves, Yuccas and Dyckias attempt survival without any assistance from me. The winter had several cold fronts, often reaching the low 20s. My plants had fared quite well up until the very last front (which happened to come after a strong warm-up, thus fooling many of the plants). But that last one did the damage and weeded out the tough ones from those that were borderline.
I've been waiting to see if any resprouted or if they simply rotted. The results are in.
Variegated Thread Leaf Agave (Agave schidigera 'Shira Ito No Ohi') : Neither the in-ground or potted one survived.
The Red Billbergia (possibly Cryptbergia 'Red Burst) took severe damage, though one small sprig survives.
Aloe 'Hedgehog' (Aloe humilis 'Hedgehog'), as expected, got hammered. No sprouts seen yet (and I'm not anticipating any).
Rattlesnake Agave (Manfreda maculosa) always dies back to the ground with any freeze and then returns.
The hanging basket of Agave lophantha 'Quadricolor' actually fared quite well. There was some minor damage (already removed) but considering how exposed it was, I'm quite pleased.
Manfreda 'Macho Mocha' (Manfreda x Mangave 'Macho Mocha') took some definite damage (already removed) but will easily recover.
Pale-leaf Yucca (Yucca pallida) showed no ill effects at all.
Both the in-ground and potted Agave 'Blue Glow' suffered some damage (mainly to lower leaves), but both survived.
Dyckia brevifolia 'Moon Glow' got diminished, but still has some green growth.
The potted Dyckia 'Nickel Silver' suffered some minor damage, but appears to have pulled through.
Not surprised to see that the potted Red Yucca's (Hesperaloe parviflora) suffered no ill effects.
All of the potted and in-ground Soap Aloe (Aloe maculata), of which I have many, turned to mush.
I had hopes that perhaps the in-ground ones would return from sprouts, and I was pleased to discover that under all the rotting leaves, growth was returning.
Sometimes, even the center of the plant survived and was producing new growth.
Soft-leafed yucca (Yucca recurvifolia) did just fine.
The 'Cherry Coke' Dyckia produced mixed results. The one planted in the backyard (with some tree cover) only had minor leaf damage.
But the two more-exposed, front yard specimens were severely burned, though small sprouts are visible on at least one of them.
I was surprised that the Twin-flowered Agave (Agave geminiflora) was killed by the low temperatures.
But was completely unsurprised that the Calamar Squid Agave (Agave bracteosa 'Calamar') were unscathed.