Dioon spinulosum is a 'bit' frost tolerant... in other words, if you have mild frosts, it will tolerate them. Severe frosts will defoliate them quickly... but that doesn't necessarily mean the plant will die. There are growers here in California that routinely have cold snaps down to about 22F and lose very few if any plants... they just don't have leaves for a while.

Many Cycads will defoliate at cold temps and not suffer trunk damage. New leaves arrive as the weather turns.

Cycas revoluta, the Sago, is well known for retaining its leaves at very cold temps. Mine begins to show some leaf damage at about 20F.

Macrozamia moorei is another one that comes to mind that doesn't show leaf damage even in the upper teens.

In a warm climate where there is a long growing season, you can get away with defoliation because there is ample time for recovery and growth. However, where growing seasons are short, defoliated plants may weaken over time as they regulalrly try to catch up and are unable to accumulate sufficient resources for consistent growth.

x

ewwww,why did you pick that name?

I thought I would add some images here of Dioon spinulosums, just so others might know what they look like. The last image is of a nice but rare variegated specimen.

I seen this cycad at Home Depot the other day and was curious. It was tagged as hardy from 20-30 F. Couple questions... What temp will kill this species? Has anyone grown these on the East coast? (sucessfully in the ground zone 9a?) How many times will this cycad flush a year? How pest resiliant is it? Growth rate? I have 2 Sago Revolutas for comparison, 1 that I fought a scale issue with.

Nice pics!
seventhlegend... I think if they are being sold at your home depot then they are probably hardy in your area since the home depots north of a zone 9 dont sell spinulosum. I would protect it below 25F. It will lose its leaves before then but the trunk should stay firm.

Good luck!
-Alex

Our home depot is always selling coconuts, and they sure can't live in our zone. So don't always think what is sold in your zone by Home Depot will make it there.

Dioon spinulosums will survive down to about 22F... but that depends on how long it's there... if briefly that cold, the caudex will survive, but all the leaves will be gone (they leave at about 28F). But if you have prolonged freeze, maybe even 25F or 26F will kill one, particularly a young one.

I havent noticed it with all plants (since I have tons of plants at my HD that cant tolerate our winters), but Ive noticed that areas with warmer winters have many different types of cycads unlike areas to the north.
Since they are so nice definitely protect them in a 9a winter!
Good luck!
-Alex