With the artic cold front headed this way i decided to conduct another cold hardy experiment. This time we have a run of the mill coontie that was planted out as a 1g last year and ran over by a lawn mower a few times with a year old macrozamia elegans(blue leaf on left). M. Elegans is one of the most southerly growing and cold tolerant Australian cycads where they are found in a zone 9a climate.  Both are planted under a pecan tree in a rich sandy loam with natural leaf litter.  

Next year my stenomera will be large enough to test as well. 

Good to see people who are into experimenting with plants! Macrozamia conferta, concinna, heteromera, platyrhachis and viridis should be enough hardy for your location 

4 hours ago, TexasColdHardyPalms said:

With the artic cold front headed this way i decided to conduct another cold hardy experiment. This time we have a run of the mill coontie that was planted out as a 1g last year and ran over by a lawn mower a few times with a year old macrozamia elegans(blue leaf on left). M. Elegans is one of the most southerly growing and cold tolerant Australian cycads where they are found in a zone 9a climate.  Both are planted under a pecan tree in a rich sandy loam with natural leaf litter.  

Let the test begin!  I presume that you will be following up with the results and temps they are exposed to.  They both look pretty small for serious cold.

1 hour ago, Kenarr09 said:

Good to see people who are into experimenting with plants! Macrozamia conferta, concinna, heteromera, platyrhachis and viridis should be enough hardy for your location 

I have all of those and believe stenomera will prove to be the hardiest.  I have to get them up to size before i test.  

1 hour ago, Tracy said:

Let the test begin!  I presume that you will be following up with the results and temps they are exposed to.  They both look pretty small for serious cold.

Absolutely.  That area is a cold sink and im sure they will see 15f next week for sure.  I know that johnsonii is leaf hardy to 22f and communis starts to burn at 22, defoliates at 20.   Both will burn back to the ground at 14f but will come back without issue. Communis never really makes a trunk so it can grow where a sago will. I feel very confident saying that a johnsonii could trunk and never die if the temperature only dropped to off 19-20f. So a solid florida/arizona/california 9a plant or mid 9a Texas.  

Btw, the only good thing about our winters is that it completely eradicates scale. 

After 24 hours below freezing and a droop to 15.4 the coontie looks like it will burn for sure. It is 28 right now so we'll  have another 24 hours to go below freezing for sure.  Macrozamia looking good but has to get through another 18-20 degree night and many cold hours. 

Joe, any experience with kill temperatures for macrozamia trunks?  How does M moorei compare?  

Thanks,

Steve

 

@Turtlesteve    I haven't had the cojones (or disposable cash) to test a trunking macrozamia yet.  I know Moorei is right on par with Johnsonii as far as leaf hardiness goes(20F dry they burn) and both of those are actually just slightly less leaf hardy than Sagos in our climate.  Most Sagos start to burn right around 20 and all defoliate in the upper teens when dry and if there is ice or snow they burn at a much higher temperature.  I can tell you that most unprotected sagos with 12-18" of vertical trunk in pots will survive 13F.  That temperature is right on the ragged edge of trunk hardiness as most of the ones that survived pushed one of those dwarf & disfigured "I almost died" flushes.  None of my large 3-5' trunk sagos had any issue with that temperature and flushed perfectly normal.  Revoluta caudices smaller 8-10" tall are not hardy in pots for anything less than 17-18F and softball size sagos will die in the low 20's in pots. 

Based on all of this information I would have to think that a Johnsonii & Moorei trunks are hardy to at least 17-18F before damaged.  The only difference that I could see is if there is a partial issue with the growth point that it could jam like a palm tree and that would kill it because it doesn't one massive flush like all other cycads.  Large Dioon ,cycas, lepidozamia and Zamia that I had die from cold never had any trunk damage they all lost the growth point and rotted out from the top while Encephalartos have been different and always rot from the bottom.

16 minutes ago, TexasColdHardyPalms said:

@Turtlesteve    I haven't had the cojones (or disposable cash) to test a trunking macrozamia yet.  I know Moorei is right on par with Johnsonii as far as leaf hardiness goes(20F dry they burn) and both of those are actually just slightly less leaf hardy than Sagos in our climate.  Most Sagos start to burn right around 20 and all defoliate in the upper teens when dry and if there is ice or snow they burn at a much higher temperature.  I can tell you that most unprotected sagos with 12-18" of vertical trunk in pots will survive 13F.  That temperature is right on the ragged edge of trunk hardiness as most of the ones that survived pushed one of those dwarf & disfigured "I almost died" flushes.  None of my large 3-5' trunk sagos had any issue with that temperature and flushed perfectly normal.  Revoluta caudices smaller 8-10" tall are not hardy in pots for anything less than 17-18F and softball size sagos will die in the low 20's in pots. 

Based on all of this information I would have to think that a Johnsonii & Moorei trunks are hardy to at least 17-18F before damaged.  The only difference that I could see is if there is a partial issue with the growth point that it could jam like a palm tree and that would kill it because it doesn't one massive flush like all other cycads.  Large Dioon ,cycas, lepidozamia and Zamia that I had die from cold never had any trunk damage they all lost the growth point and rotted out from the top while Encephalartos have been different and always rot from the bottom.

I appreciate the info - I am hoping that I will find a few winners for zone 8a here (with minimal effort to protect them).

Steve

The macrozamia is going to be more cold hardy. Even though there are exceptions, all smaller Macrozamias should handle 17 without getting burned, where coonties, are going to burn at 17. I know I had containerized communis that were untouched at 15. For an experiment, put a far north macrozamia next to it and then see if it makes any difference. I will bet macrozamia stems would take low teens, but the problem is water. If they get real wet and cold, rot could come later, where being dry at the same temperature might be alright.  I'd be afraid to put out stenomera. They seem too picky here, but you are doing better with those kinds of things in your location.  Tom

We dropped down to 12 the morning of the 3rd at the nursery and it looks like that temp actually burned the M. Elegans. I only went down to 16.4 at my house and I wish I would have put one of them in the ground over here to test since it is so much colder at the other property.   It looked fine 3 days after it hit 17 without looking burnt while the Coontie was clearly very burnt. I didn't get a pic while I was over there though. 

As I mentioned before the Communis in the ground was smoked at 20 back in December but had a little burn @ 22 degrees at my house. I don't know how many years in a row they can completely defoliate and still come back, but I suspect indefinitely just like Cycas and zamia will.   Next year I plan on testing Heteromera, Diplomera, Stenomera, Concinna, conferta, Montana and viridis as well as planting out quite a few of these elegans.

I take it a coontie is a type of Cycad. Never heard the word before

I think it is officially called Zamia Floridiana and not Zamia Integrifolia any longer.  Its the native Zamia found in Florida and I believe Coontie is what the Native Americans called the cycad.

My first horticultural brush with the law was getting caught with a bag of seed i picked up in a state  park, somewhere between tampa and ft meyers on our way to pine island. They busted me with a stern slap on the pride and i had to dump the bag i had ... but i didnt mention the big bag in the trunk of the rental and they didnt ask so.......got pretty decent amount of germination too and no have a patch of my own to harvest seed off of