I think you may have a serious challenge on your hands :-) Anything lower than a zone 8 is going to pose significant hardiness issues for you. It is rated to zone 8b or a minimum temp of 15F. Even in zone 8, garrya can experience significant foliar damage in a colder than typical winter and I fear it will be cut back at least to the roots in zone 6....more likely even fatally so. If you look at the native range for this plant you will see it is limited to a very narrow coastal strip of northern California and southern Oregon - zones 8 and 9. It generally will not tolerate the more extreme (hotter in summer and colder in winter) inland climates. It does very well here in the PNW as marine influences prevent severe temperature extremes.

Protecting the plant in winter would seem to be SOP but I have no idea how you could accomplish this yet still reap the rewards of this plant's winter bloom season. Even containerizing the plant would pose problems as this wants to become a good sized shrub and needs some maturity to develop a good flowering habit. Hard to see that happening indoors in January.......

btw, the UK has a very mild climate, which allows the growth of plants like the Garrya. The coldest zone is the equivalent of our 7a and that is limited to a few smallish inland areas. Most of the country is firmly in a zone 8 and with certain coastal areas as high as a zone 10.

Thanks for your reply.
I know it will be a great challenge to keep it in good condition in my zone but on the other hand many plants rated to zone 8 and higher appeared to be hardy here eg. Fatsia or Phygelius. They thrived many winters with little or no protection. Even Monkey Puzzle tree survived few weeks with harsh frost. And I mean harsh -30C.
Anyroad, It's gonna be an experiment, I won't bother again if it doesn't survive.

Both the phygelius and the fatsia are rated to a lower minimum temp than the garrya -- these are true zone 7 plants and possibly lower if in an appropriate microclimate. Ditto the Araucaria. I would not group the garrya in the same category. FWIW, some of the Pacific coastal native plants are very specific in the conditions in which they will thrive and while technically perhaps sufficiently cold hardy (and the garrya is NOT), they simply will not thrive in more inhospitable continental climates.

But other than the cost of the plant and your effort, it certainly won't hurt to try :-)

I do not want to group garrya with them plants as the same zone plants (though I keep finding info on fatsia and phygelius as zone 8 plants), just wanna show that plants rated to higher zones are able to grow where they're not supposed to.
Anyway, your realistic opinion about my optimistic notion is much appreciated. Still I believe there's someone out there who grows garrya in cold climate with success.

The USDA Hardiness Zones aren't based on single minimum temperatures (like 15F). They are based on ranges of average annual minimum temperatures recorded during specific 15 year periods. A plant being thought to be hardy to a particular USDA zone does not equate into it being hardy to a specific predetermined single temperature. It means that is the coldest zone it will persist in, or is the first zone where it begins to fail - or whatever is meant by the individual assigning it that zone in each case.

Commercial sources appear to have a tendency to state a plant is hardy to a zone which has a 15 year average minimum range that includes the temperature to which the plant is thought to be hardy. Therefore, if a plant burns up at 15F then it is assigned a Zone 8 by catalogs etc. Since the 10-20F range is not the entire range of minimum temperatures seen in USDA 8 but rather the spread of average minimums, a plant taken out by 15F will not be a long term success in many parts of Zone 8 at all. There is liable to be winters that fall below 10F and others that do not get down to 20F.

The USDA web site recommends choosing plants rated one zone hardier than the zone you are in.

Coast silktassel, like bay laurel is one of the broad-leaved evergreens that is so sensitive to cold winds it can be seen blackened by them in its native habitat.

Thanks for the info, bboy. I was tempted to try it in my zone, since it is so lovely. No more.
Renee

"But have seen large shrubs in England in places where temps happen to get much lower." I don't know where you saw these plants but -10 is an extraordinarily low temp for England. If temps did ever get that low it would be for a very short duration and would be a very rare event. The coldest EVER recorded in England was -26.1 degrees C on 10 January 1982(14.98 degrees Fahrenheit). Where I live Garryas are common but our average minimum temp even in Feb (the coldest month) is above freezing. They are particularly common in coastal districts where the climate is mild and they withstand salt.

Yes, fatsi is not a "true Zone 7 plant". I think the serious top damage seen periodically here in Zone 8 typically starts at about 10 degrees F. If the predicted "vicious" winter materializes this time there will be ample opportunity to see this plant collapse once again.

I planted several one gallon plants under low-branching cypresses on Camano Island, where these conifers might have provided some frost protection with their evergreen tops.

Nah. Froze to the ground during what must have been the first winter. Replacement top growth has been very weak.

Older, larger specimens said to be hardier.

.... and just to reiterate what gardengal said .... Even if you could get Garrya through the winter by bundling it up that rather defeats the object of growing it which is the fact that it flowers during the winter. (November to February here - most common cultivar 'James Roof' which has tassels up to 10in long). But if you can get a reasonably priced plant why not try it?

I know that temps in England rarely drop below -10C. I talked to the local citizens and they said they got -10/-15C every winter just beacause of local microclimate.
As for fatsia, well, maybe in my continental climate its wood ripens good enough to endure harsh frosts. Last winter the one I keep in pot and overwinter in an unheated cottage defoliated after few nights of -5C inside. The one in the ground looked just fine even with -20C and lower.
But speaking of garrya, it won't bloom when its too cold will it?, so I'd expect it to flower in November or March here (depends on winter - mild or severe?). It is a shrub difficult to get hold of, and I'm getting one more from the UK. Gonna try it anyway, you know-nothing ventured, nothing gained.
Cheers everyone

I'm still curious about where you saw Garrya in England and where the temperature gets to -10 to -15c. Can you tell us?

The link gives info about choosing Garrya and propagating it.

Here is a link that might be useful: Garrya info.

Cheshire, Northwich/Rudheath. Used to work there.
They also get plenty of rain in the Summer
thanks for the link :)

Well that's interesting. I was just really intrigued about those temperatures. I've just looked up Northwich and Wiki says, "The climate is generally temperate with few extremes of temperature or weather. The mean average temperature is slightly above average for the United Kingdom as is the average amount of sunshine.[23][24] The average annual rainfall is slightly below the average for the UK.[25] There are few days when snow is lying on the ground, although there are some days of air frost.[26][27]

On the accompanying graph the average min temp in Jan and Feb is 1C i.e. above freezing. So I still don't quite get where those low temps came from, but it certainly describes a Garrya friendly climate :)

Here is a link that might be useful: Northwich climate

If I followed all those scientific info It'd mean I live in Iceland, cuz according to all those "means" Summers in my place are prettyy cold- not cool- cold and Siberian Winters. The truth looks a bit different. Summers are really hot and absolute min. temp in winter was -35C many many years ago. You shoudn't just base everything on numbers. There are certain places with certain microclimates. Do you know that there's a desert in the very center of Europe?

According to the zone maps, Cheshire is a pretty firm zone 8. And since the zones represent an average minimum temp, I guess the -10 to -15C or so is possible, if not typical. That's still a big swing from the -23C you are likely to encounter in your location.

And should you still want to try growing this plant, I'm not sure you would ever reap the benefits of its winter flowers/catkins. Whatever protection you'd devise to secure the plant from excessive cold - which would be a requirement in zone 6 - would either encourage the shrub to attempt to bloom while under protective wrapping or abort the flowering altogether. I don't think you can count on the shrub blooming out of season, despite your intents.

But it's your nickle!!

Look, you will not put me off. It is just an experiment. And if I fail it will only be a lesson. I'm gonna put up a pretty big greenhouse in my garden in Spring so I can grow the shrub in it and enjoy its catkins anyway :D

There actually a number of areas within Europe that are classified as "deserts" but I'm not sure how that is relative to this discussion. A desert is not defined necessarily by climate - Antarctica is technically considered a desert - but as an area devoid of much vegetation and of soil and/or climatic conditions that do not encourage the growth of much vegetation.

Whether or not a zone 8 marginally hardy plant is likely to thrive or even survive in a zone 6 location is really the question at hand. If you can provide a microclimate that can replicate a mild zone 8 winter, then your chances are very good. But I am far less sure that just wrapping or otherwise protecting an inground planting without benefit of a highly favorable microclimate will produce the same results. To say nothing of how very necessary winter protection is likely to impact the winter flowering.

Will definitely have to be overwintered under cover or trained flat on a sheltered wall and then covered as needed.

'You shouldn't just base everything on numbers' - I'm not. My doubts are based on living in England through many summers and winters and seeing Garry growing happily in many places. Obviously there are micro-climates but I'm just curious to get to the bottom of the claim that there is somewhere in England that experiences -10C as a matter of course in the winter and where Garrya also thrives. The 2 just don't seem compatible. Even last winter, the coldest Winter since 1987, the lowest temperature in NW England was -17.0C at Woodford, Cheshire near Manchester airport. Lowest temperature in the whole of Britain was -22.3C at Altnaharra in the Northern Highlands of Scotland.

I'm not trying to put you off experimenting with Garrya. I have to say I actually find it a rather dull shrub and if it didn't perform in the dead of winter I'm not sure how many people here would bother to grow it. But you've clearly set your heart on it. Best plan is to plant it and come back here with an account of your experiences so we can all see how you are getting on. Prove us doubters wrong :)!

If it's USDA 6 there is no way it will live there without significant assistance.

A winter heated greenhouse sounds like an ideal compromise to growing this shrub in your climate. Good luck!