Australian Hardiness Zone Maps

[greysrigging]

Aussie hardiness info and maps.
https://www.anbg.gov.au/gardens/research/hort.research/zones.html

[kinzyjr]

C'mon Canada!  The USA needs a mountain range across the top of the continent so we can have a zone map like this!

[sandgroper]

Great maps!

[greysrigging]

6 hours ago, kinzyjr said:

C'mon Canada!  The USA needs a mountain range across the top of the continent so we can have a zone map like this!

We are surrounded by oceans which definitely moderates our climate, particulaly  re cold outbreaks

[cbmnz]

This one for NZ looks about right. Auckland city , within 20km of downtown though is just as warm as Northland and close to 10b..And some areas of the most inland Northland are hardly less frosty then here, so are a low 9b. The exposed parts of Wellington are genuine 10a but with cool summer. So things like Avocado and Queen palms grow far better here near the Northermost 9a/9b boundary. This winter my extreme low was -2.0 so very solid 9b, second year in a row.

Edited September 18, 2019 by cbmnz
Fix typo

[Tyrone]

Nowhere around Perth is zone 11 except Rottnest island and maybe Garden Island and possibly Rockingham including Point Peron. The last map was the only one to show a difference between Albany and Perth. There’s a huge difference in reality.

[greysrigging]

3 hours ago, Tyrone said:

Nowhere around Perth is zone 11 except Rottnest island and maybe Garden Island and possibly Rockingham including Point Peron. The last map was the only one to show a difference between Albany and Perth. There’s a huge difference in reality.

Agreed.... this bloke explains it thus...
 

Plant Hardiness Zones for Australia

by Iain Dawson (Horticultural Research Unit, ANBG) 1991
(Iain has since retired from the Australian National Botanic Gardens)

Plant hardiness maps allow producers to label their plants as being suitable for particular areas, and, in theory at least, this results in happy customers who can confidently buy plants that will survive in their locality. Early in 1990 the United States Department of Agriculture (USDA) published an updated version of their map of plant hardiness zones. This divides the United States into 11 zones (1-11), characterised by their average minimum temperature. Zones 2 to 10 are also subdivided into a or b, giving a total of 20 zones or sub-zones. These zones of course only apply to plants growing out of doors with no protection, but which are provided with adequate water.

It has been suggested that such a map would be useful for Australia (Australian Horticulture, May 1990). This would be an aid to the plant buyers in Australia, as well as helping exporters to the USA describe the hardiness of their plants in a common language. Similar maps have been drawn before, such as those on the back of many seed packets, but as far as I know none has ever been comparable with the American system.

The statistic used by the USDA is the average annual minimum temperature. This causes some confusion straight away, because in Australia we use this term to mean the average minimum temperature over the whole year , whereas the USDA means the average, over ten or more years, of the very lowest temperature (the absolute minimum) observed for each year for each meteorological station. I prefer to call the USDA term the average annual lowest temperature. This figure tends to make places look very cold! For example, Florida, which we think of as a warm place, is in the US Zone 10 which has minimum temperatures from 30°F to 40°F (-1°C to +4°C). Zone 1 (e.g.central Alaska) is below -50°F (-45°C) which is very cold!

I have used the same statistic for Australia, but rather than use US zones directly I have modified the limits for each zone. This is because Australia, in winter, is much warmer than most of North America in winter, so the lowest US zones aren't needed. All of Australia (excluding Macquarie Island) is covered by just over four US zones (7b to 11). To make the map more useful to Australians I have created 7 zones to fit our climatic range, and used metric units. The limits to each zone, and a comparison of US and Australian zones, are shown alongside the map. Initially I tried subdividing each zone (except for 7), to a total of 13, but it proved too difficult to map these on a scale suitable for internet publication.

 

As might be expected, the main factors determining average minimum temperature are altitude, latitude and proximity to the coast.

• Zone 1 covers the alpine areas of south eastern Australia.
• Zone 2 the tablelands of south east Queensland, New South Wales and Victoria, and the uplands of central Tasmania.
• Zone 3 includes much of the southern half of the continent, except for localities on or near the coast. Many of our weather stations are on the coast or on off-shore islands (some of them are lighthouses) and these are often a zone or two higher than adjacent mainland stations because of the warming effects of the ocean in winter.
• Zone 4, because of this warming effect, covers a broad area from coastal Queensland across the continent to Shark Bay and Geraldton in the west, also includes the Mornington Peninsula, areas adjacent to Spencer Gulf and Adelaide, the south western coastal zone, Sydney and the north coast of NSW, along with a number of localities dotted all around the southern coast of the continent.
• Zone 5 covers, some of the Queensland coast, Western Australia north of Shark Bay and across the top end.
• Zone 6 includes the Queensland coast north of Cairns, Cape York Peninsula and the coast of the Northern Territory.
• Zone 7 is mainly restricted to islands off the north coast.

There are many problems with maps of this type. For example, the spread of weather stations is insufficient to give good resolution of the zones and too many places with different climates are lumped together. In Australia we have only 738 stations with a record of more than ten years. This is one station per 98,491 hectares! Admittedly, the more populated areas have relatively fewer hectares per station but the basic problem remains. Even worse are the problems of local factors such as aspect, altitude, proximity to the sea and so forth. For example, Mt Isa has three climatic stations with more than a ten year record. One is in Zone 4a, one in Zone 4b and the other is in Zone 5a. Sydney residents can choose between Zones 3a to 4b depending which station is used. Most other cities have similar problems. Everyone is aware that different locations in the same city or suburb are suitable for different plants but it is hard to quantify these differences and even harder to draw a meaningful map. There may even be a case for publishing a list of weather stations and their zone Classification so that people can decide for themselves which is the most appropriate location to use for their local conditions.

Plant hardiness refers to their ability to survive the conditions of a particular location, including tolerance of heat, soil moisture, humidity and so on. This map is based only on how well they survive low temperatures in winter. Even that is a gross oversimplification. For example, are plants affected more by a single extremely low temperature night, or is the number of days of frost (the duration of winter) more important? In fact both are important, but the statistic for the map only relates directly to the former. Another limitation is that often plants will survive in an area for some time, but every now and then there will be a catastrophic cold snap that will kill them. Some risk evaluation - the probability of getting a particularly severe low temperature - often would be more useful for each locality rather than the average conditions.

Low temperature is not the only determinant of plant survival. Other environmental factors such as high summer temperature, humidity, soil temperature, etc. may be equally important. Also, many plants will survive in a locality but won't flower if the daylength is inappropriate or if they require vernalisation (a particular duration of low temperature). The low temperature statistic is only appropriate for woody perennial species, and even then its use is limited. With annuals the time of planting can often be adjusted to allow growth beyond their normal geographical range.

The map is thus only useful as a very broad guide. It needs interpretation that takes into account factors other than low temperature that limit plant growth as well as local knowledge.

An alternative system for describing plant hardiness is to use indicator plants (the USDA also publishes a list of these to go with their map). Common plants with known limits to their range are generally used for this purpose. For example, many people will know whether lemons will grow in their locality. If you then say Geraldton Wax will grow more or less where lemons will grow you have defined the range of Geralton Wax with some accuracy (whether or not it will flower is another problem). Unfortunately no two plant species seem to have exactly the same requirements and even within a species there are differences. 'Meyer' lemons, for example, are more cold tolerant than 'Eureka'. You can really only define core areas and they are often very arbitrary.

At some time in the future I think we will probably get around the problems associated with plant/climate maps with much more sophisticated database systems that combine complex climate statistics and advanced plant growth models. There are already software packages available to help you select landscaping plants. Two that I have seen are the 'Grow What Where' computer version, published by The Australian Plant Study Group, and 'Plantguide' from Arbordata. However, these have limited climatic inputs. You are asked, for example, to select between fairly vague zones such as 'warm temperate' or 'eastern tablelands'. Climatic data bases that allow you to assess the chances of particular climatic events taking into account some local factors (eg. what are the chances of getting more than five consecutive nights with temperatures lower than -10°C on a south facing slope in Canberra?) combined with data bases containing detailed knowledge of plant responses to their environment (eg. how many nights of frost can Pandorea jasminoides survive?) will go a long way towards answering the question of what grows where.

In the near future, when the customer asks if a particular plant will grow in their garden, the retailer will probably tum to a computer, not a map, to find the answer.

 

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[necturus]

So what grows in Canberra? It's hard to get much information online, but it sounds like the botanical garden grows some surprisingly cold sensitive stuff.

[greysrigging]

7 hours ago, necturus said:

So what grows in Canberra? It's hard to get much information online, but it sounds like the botanical garden grows some surprisingly cold sensitive stuff.

Terrible things thrive in Canberra....they're called 'Politicians'

[greysrigging]

7 hours ago, necturus said:

So what grows in Canberra? It's hard to get much information online, but it sounds like the botanical garden grows some surprisingly cold sensitive stuff.

Climatically, Canberra has cold winters by Australian standards with a long frost season, so many cooler climate species grow very well in the Gardens there.

Climate

Under the Köppen-Geiger classification, Canberra has a subtropical highland climate (Cfb).^[112] In January, the warmest month, the average high is approximately 28 °C (82 °F); however, in July, the coldest month, the average high drops to approximately 11 °C (52 °F).

Frost is common in the winter months. Snow is rare in the CBD (central business district), but the surrounding areas get annual snowfall through winter and often the snow-capped mountains can be seen from the CBD. The last significant snowfall in the city centre was in 1968.^[96]

The highest recorded maximum temperature is variously reported as 42.2 °C (108.0 °F) on 1 February 1968,^[96] or as 42.8 °C (109.0 °F) at Acton on 11 January 1939.^[113] Winter 2011 was Canberra's warmest winter on record, approximately 2 °C (4 °F) above the average temperature.^[114] Canberra is being impacted by Global Warming indicated by a long-running tendency for temperatures to increase.^[115]

 

Temperature change in Canberra

The lowest recorded minimum temperature was −10.0 °C (14.0 °F) on the morning of 11 July 1971.^[96] Light snow falls only once or twice per year, and it is usually not widespread and quickly dissipates.^[96]

Canberra is protected from the west by the Brindabellas which create a slight rain shadow in Canberra's valleys.^[96] Canberra gets 100.4 clear days annually.^[116] Annual rainfall is the third lowest of the capital cities (after Adelaide and Hobart)^[117] and is spread fairly evenly over the seasons, with late spring bringing the highest rainfall.^[118] Thunderstorms occur mostly between October and April,^[96] owing to the effect of summer and the mountains. The area is not very windy and the breeze is at its strongest from August to November. Canberra is less humid than the nearby coastal areas.^[96]

[bubba]

Australia is amazing and so is New Zealand.

[sipalms]

I have seen Queen Palms growing in Canberra, they looked pretty battered and frost damaged, but were reasonable size.

We were there in June and one morning had -4 with one of the most 'frosty' frosts I'd ever seen anywhere (in terms of sheer amount of ice). Nothing like we see here. Everything was white.

[sandgroper]

1 hour ago, sipalms said:

I have seen Queen Palms growing in Canberra, they looked pretty battered and frost damaged, but were reasonable size.

We were there in June and one morning had -4 with one of the most 'frosty' frosts I'd ever seen anywhere (in terms of sheer amount of ice). Nothing like we see here. Everything was white.

I've seen Canberra like that too many years ago, I thought it was snow looking out the window of the bus (I've never seen snow)

[cbmnz]

Even in Taupo, seems Queens do fine. This resort strategically has its Nikau in planter boxes by the looks though.

https://www.oasistaupo.co.nz/gallery#galleryd9d244274e-6

As far as I know there are no CIDP surviving in Queenstown and surrounds, but there are these in Roxbrough. Must be hardly anywhere in Aust & NZ  less than ~500m elevation where they won't grow.

https://www.google.co.nz/maps/@-45.5397673,169.315936,3a,75y,94.45h,81.61t/data=!3m7!1e1!3m5!1sKUtDSk1-Gw6XlRZMfQqzGA!2e0!5s20130101T000000!7i13312!8i6656?hl=en

 

 

[Tyrone]

On 10/21/2019 at 5:01 PM, cbmnz said:

Even in Taupo, seems Queens do fine. This resort strategically has its Nikau in planter boxes by the looks though.

https://www.oasistaupo.co.nz/gallery#galleryd9d244274e-6

As far as I know there are no CIDP surviving in Queenstown and surrounds, but there are these in Roxbrough. Must be hardly anywhere in Aust & NZ  less than ~500m elevation where they won't grow.

https://www.google.co.nz/maps/@-45.5397673,169.315936,3a,75y,94.45h,81.61t/data=!3m7!1e1!3m5!1sKUtDSk1-Gw6XlRZMfQqzGA!2e0!5s20130101T000000!7i13312!8i6656?hl=en

 

 

CIDP will grow anywhere in Australia except maybe the Alps and the true tropics like Darwin, but then I could be wrong about Darwin they may grow well there too. I remember that the few CIDP I saw in Singapore on the equator essentially looked terrible.

[cbmnz]

Can't figure exactly what palms are  around this pool. Best guess is Kings/Alexandrae. Great job of faking a tropical island look using plants that will grow in NZ at 36S. Amazingly those gaint bird of paradise will grow where I live too, so they must tolerate short duration freezes to -3C or so. Have noticed some large ones around.

 

[Daryl]

The rain forecast for coastal Queensland has up to 1000mm (40 inches) of rain over the next two weeks...should be interesting