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UK Hardiness zones


SP1986

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Posted
  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral

    The plant hardiness zones (showing what the annual minimum temperature of the year) are all consistent in the numbers they produce, and the lower the numbers show that the plants have to more hardy as it's cold, and the higher humbers indicate that less hardy plants can survive in those conditions.

    The UK mainland ranges between 7-9 (10 in the Scilly Isles)

    So I compared the USA to the UK as these Hardiness zones are a good assessment of average climate around the world.

    The minimum zone is 1 which is Arctic, and Maximum is 11 which is tropical.

    So as Scilly Isles is 10 it can host tropical plants and they will survive there happily.

    Here are two maps, one of UK and one of SW USA

    http://www.usna.usda.gov/Hardzone/hzm-se1.html (USA)

    http://www.gardenweb.com/graphics/zones/hze1.gif (UK)

    This really shows how warm we are in comparison to most other continental places in the world.

    For example Western England/Ireland and Wales are not only on a par with the north Mediterranean, but also with North and central Florida, and lesd cold tolerant (in plants) than Texas and Mississippi.

    Remarkable really!

    What this means is that plants that would be considered tropical/sub-tropical could probably be happily grown on these western UK coasts. When we express tropical we are saying, palm trees, banana trees, miniature coconut trees, bird of paradise? and tree ferns.

    How about that!

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    Posted
  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral
    We have a few palm trees locally, but there are tons of them in Torquay.

    I'm quite dubious about the Torbay Palm (Cordyline Australis), it's not actually in the palmae/arichecea(sp?) family which means they are not technically true palm trees. However their origin would have probably been from Australia or New Zealand originally (judging by it's name) so there is a point to that, probably related to the Yucca in some form. All true palms have fronds and pinnate leaves

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    Posted
  • Location: Brixton, South London
  • Location: Brixton, South London
    The plant hardiness zones (showing what the annual minimum temperature of the year) are all consistent in the numbers they produce, and the lower the numbers show that the plants have to more hardy as it's cold, and the higher humbers indicate that less hardy plants can survive in those conditions.

    The UK mainland ranges between 7-9 (10 in the Scilly Isles)

    What this means is that plants that would be considered tropical/sub-tropical could probably be happily grown on these western UK coasts. When we express tropical we are saying, palm trees, banana trees, miniature coconut trees, bird of paradise? and tree ferns.

    How about that!

    Well yes indeed although the Tree Fern Dicksonia Antarctica (a native of NZ) is hardy down to -15c. Certainly I grow them easily in south London with absolutely no winter protection.

    Regards

    ACB

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    Posted
  • Location: Western Isle of Wight
  • Weather Preferences: Snow, Storm, anything loud and dramatic.
  • Location: Western Isle of Wight

    If there is ever a bad winter again lots of these plants will die, unless they are protected with insulation during the cold period.

    Quite amazing what actually grows in some parts of the UK, i didn't realise Scilly is rated tropical.

    Bananas may well grow in Scilly, no doubt they'll blow over :)

    Russ

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    Posted
  • Location: Swallownest, Sheffield 83m ASL
  • Location: Swallownest, Sheffield 83m ASL

    Fantastic scope for plants in the UK.. So many different micro climates i suppose..

    We have a bottle brush plant and apparently they don't grow this far north.. Its over 6ft high with a similar spread.. Inlaws have one and the seeds are happily sprouting.. I'll post a photo of ours over the next few days.. cracking plant but not good for the grass.. :)

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    Posted
  • Location: Shrewsbury
  • Location: Shrewsbury
    I'm quite dubious about the Torbay Palm (Cordyline Australis), it's not actually in the palmae/arichecea(sp?) family which means they are not technically true palm trees. However their origin would have probably been from Australia or New Zealand originally (judging by it's name) so there is a point to that, probably related to the Yucca in some form. All true palms have fronds and pinnate leaves

    It's called a "Cabbage Tree" (or "Te Kauka" in Maori) and it's native to New Zealand, where it grows poleward of 45 degrees south and up to heights of 1000m (North Island) and 750m (South Island); the average southern English winter is no problem at all for this plant.

    Somebody a few years back seems to have thought they could make a fast buck fooling Brits into thinking they were palm trees; I'm no gardener (and certainly no gardening snob) but I can't resist correcting those who think they are.

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    Posted
  • Location: Kingdom of Fife: 56.2º N, 3.2º W
  • Location: Kingdom of Fife: 56.2º N, 3.2º W

    Be wary of US hardiness zones, they don't translate well to the UK. We have wet milder winters with spurts of growth and snap frosts that are the death of some plants that can sustain dry freezing conditions in a dormant state.

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    Posted
  • Location: Shrewsbury
  • Location: Shrewsbury
    Be wary of US hardiness zones, they don't translate well to the UK. We have wet milder winters with spurts of growth and snap frosts that are the death of some plants that can sustain dry freezing conditions in a dormant state.

    That's cause the US zones are meant for a continental climate- in Texas you are guaranteed, every year, summers with days on end of 30C+ and plenty of sun; in England you are not. The fact that the lowest temps you can expect in a typical winter are similar is just one coincidence- like with two locations which both have say an average summer rainfall of 200mm; while the one has that in 4 big thunderstorms or hurricanes with nothing in between them while the other gets days on end of drizzle/steady rain.

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    Posted
  • Location: Heswall, Wirral
  • Weather Preferences: Summer: warm, humid, thundery. Winter: mild, stormy, some snow.
  • Location: Heswall, Wirral
    Be wary of US hardiness zones, they don't translate well to the UK. We have wet milder winters with spurts of growth and snap frosts that are the death of some plants that can sustain dry freezing conditions in a dormant state.

    I think they work pretty well, afterall they translate well to the climate - Florida for example is always seen as hot and wet, sub tropical in climatic terms, in reality it is temperate maritime - like the UK. These charts work well because most of the average minimum temperatures in the UK are above 0C all year around, and the only places in the USA that can ever say they have average minimum temps all year round are the southern and extreme southern coastal parts of USA. Even Texas gets cold in the winter so these charts work very well, and are truly representative of real life hardiness zones.

    What you said was brought up ina criticism of the zone maps - however I don't agree because the map only shows zones suitable for growing plants by highlighting absolute minimum temperatures. For example a Canary Palm can grow just as fast in zone 9 in western UK, that it can in zone 9 in Florida - and trust me I know, mines grown a foot in a year!

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    • 3 weeks later...
    I think they work pretty well, afterall they translate well to the climate - Florida for example is always seen as hot and wet, sub tropical in climatic terms, in reality it is temperate maritime - like the UK. These charts work well because most of the average minimum temperatures in the UK are above 0C all year around, and the only places in the USA that can ever say they have average minimum temps all year round are the southern and extreme southern coastal parts of USA. Even Texas gets cold in the winter so these charts work very well, and are truly representative of real life hardiness zones.

    What you said was brought up ina criticism of the zone maps - however I don't agree because the map only shows zones suitable for growing plants by highlighting absolute minimum temperatures. For example a Canary Palm can grow just as fast in zone 9 in western UK, that it can in zone 9 in Florida - and trust me I know, mines grown a foot in a year!

    No, as a keen grower of 'exotic' or sub-tropical plants I would have to say that the USDA climate zone maps based on average absolute winter minima only give at best a simplistic comparison of climates. Certainly, there is no serious similarity to any Floridian climate anywhere in these isles.

    They can be a starting point though, giving encouragement to grow many plants that may not be expected to survive - but often that's all they will do because while our lowest temps might not kill them, a combination of persistantly low temperatures, damp and low light levels will prevent them from thriving.

    As for palms, there are many which are being grown with a degree of success - for example varieties of trachycarpus, butia, washingtonia, jubaea, brahea, chamaerops and indeed phoenix like the Canary date palm to name but a few. However, the hardiest species generally agreed to be the needle palm, rapidophyllum, is considered pretty much a waste of time growing here because whilst it tolerates temperatures as low as the UK record, it does not receive enough summer heat to make any serious growth.

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    Posted
  • Location: Great Yeldham, North Essex
  • Location: Great Yeldham, North Essex
    No, as a keen grower of 'exotic' or sub-tropical plants I would have to say that the USDA climate zone maps based on average absolute winter minima only give at best a simplistic comparison of climates. Certainly, there is no serious similarity to any Floridian climate anywhere in these isles.

    They can be a starting point though, giving encouragement to grow many plants that may not be expected to survive - but often that's all they will do because while our lowest temps might not kill them, a combination of persistantly low temperatures, damp and low light levels will prevent them from thriving.

    As for palms, there are many which are being grown with a degree of success - for example varieties of trachycarpus, butia, washingtonia, jubaea, brahea, chamaerops and indeed phoenix like the Canary date palm to name but a few. However, the hardiest species generally agreed to be the needle palm, rapidophyllum, is considered pretty much a waste of time growing here because whilst it tolerates temperatures as low as the UK record, it does not receive enough summer heat to make any serious growth.

    I agree with you about the USDA climatic zones. The summer warmth also serves to ripen the growth of alot of the more tender plants which allows them to withstand some quite harsh frosts, especially if that frost is dry frost. It may be of interest to some that a few species of Optunia Cactus actually survive in the deserts of Canada, as far north as the Yukon territories where it can get to -40c . I had some pads sent over in spring 1997 which grew very well inded for the first summer, but turned to mush in a frost of -4c , mostly because of the soft growth (they were still growing as well in jan just before the frost!). kew gardens on the other hand grow them successfully outside as they protect the plants from rain in the autumn and winter months.

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