Not having grown it before, this is merely a well-educated horticultural guess... But given it's native range, I'd say it'd me pretty hardy but not tollerant of medium to heavy frosts. Light frosts would likely be okay.

Native jim,

Thanks for the feedback. I'm in the U.S.--California. Do the definitions of frost match those here? The numbers I would probably use are: light frost 29-32 F (-1.7 to 0 C), hard freeze below -1.7 C. Do these compare to light frost vs. medium/heavy frost?

Interestingly, when I searched for this, the comments from Australians were similar to yours (it seems few Americans grow the plant). We on the other hand, seem to assign it a zone--zone 9 seems to be common in this case (20-30F or -6.7 to -1C). I'm guessing based on what you say, and what little I've been able to gather elsewhere, that we're fine where I live. I'm actually also concerned about the sort of situation where one is interested in giving the plant to a friend. Will it survive someplace where it reliably gets say -5C every winter (but never much colder)? Did it survive the coldest winter the last few decades? And how cold did it get then?

It's a stunning plant--and hard to find in this country. It would be a big shame for it to die, although it sounds like we personally are safe--we pretty consistently hit about 28F (-2C) every winter (although once every 20 years it does drop to about -5C here...).

Thanks again.

Hey Mark,

I have known A. hakeifolia to be used by other horticulturists in Melbourne - where I live - and it does well down here, even in some suburbs around the city at higher altitudes that get colder temps in winter. You should be right as far as I'm concerned. CA is almost a homoclime of the Melbourne region, so I'd say go for it.

The most testing time for any plant will be during its establishment, especially if the plant is initially planted out as a smaller specimen. Maybe for the first winter or two - if you're really worried - just give it a bit of extra TLC. Throw a sheet over it when heavier than normal frosts are forecast, or stake a plastic sleeve around the plant during its first winter or two. After that it'd be fine on its own.

Final note, being a SE Western Australian species, you want to make sure the spot where you plant it out has excellent drainage. Either that or look for a grafted plant. Although if it's as hard to come by in CA as you said, it's doubtful you'd find a grafted specimen (maybe not...?).

Good luck.

Jim

Mark4321,
You should have no trouble with the plant in your region.
I have three plants in southern Tasmania and we frequently get frosts you are describing down here during winter and my plants have very little protection and they have never had any damage at all from these frosts. I also live in a rain shadow area with only an average of 350 mils of rain each year and I never ever add extra water to the alyogyne hakeifolia as they are a very drought tolerant plant indeed.

I know it is late to be answering this but I have just come across these posts. If it is of any help, I have one of these growing in my garden and it has done very well; our winters (in the central south wheatbelt - which is inland) can be fairly cold (-5 degrees overnight, with days somewhere between 9 and 13 degrees) but not for long periods of time. The Alyogyne hakeifolia is situated between a solid side fence and the driveway which is covered by a rather high carport roof, so it does get some protection. In fact, it has grown spindly through this protected position and lack of pruning. However, I am about to transplant it out into the open where it will enjoy full sun. But even in its present, protected position, it has flowered well. These West Australian natives are tough and provided you don't fertilise this one with any phosphorous type fertiliser, it should be ok. Good luck.