Winter Chill Hours

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igaquo1
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Winter Chill Hours

Unread post by igaquo1 »

Hi all

Looking into buying a fruit tree and got into researching the winter chill requirements of them. Winter chilling is required so certain trees have a dormancy and then can flower properly in spring. This is measured by the count of the number of hours between 0 °C and 7 °C.

Downloaded the data from CliFo and here they are if anyone's interested:

Warkworth Ews 460
Auckland Aero 179
Auckland, Henderson North 328
Auckland, Whenuapai Aws 366
Tauranga Aero Aws 401
Te Puke Ews 465
Hamilton Aws 725
Period 1997 - 2019 (mostly)

Little surprised at the Warkworth count vs Auckland sites.

As comparison, here's the minimum chilling requirements for a few fruit tree types:

Almond 500-600
Apple 400-1000
Apricot 500-600
Cherry 700-800
Citrus 0
European pear 600-800
Fig 100-200
Grape 100
Japanese plum 300-500
Kiwifruit 600-800

Cheers
Jeremy
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Jeremy B

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Re: Winter Chill Hours

Unread post by Awhituobs »

Kiwifruit is the interesting one there
in that less winter chilling with gradual warming over the coming decades might mean less viable fruit setting in some area?
Warkworth is more inland (even though it is still a relatively narrow part of Northland) than Auckland Airport
and there is good sheltered valleys etc
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Re: Winter Chill Hours

Unread post by NZstorm »

There is some steep hill country in North Auckland which will aid frost. I can imagine Warkworth being a cold spot in winter.

I am guessing Avocado is the same as citrus and does not need any winter chilling.
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Re: Winter Chill Hours

Unread post by igaquo1 »

Awhituobs wrote: Thu 02/07/2020 10:42 Kiwifruit is the interesting one there
in that less winter chilling with gradual warming over the coming decades might mean less viable fruit setting in some area?
Warkworth is more inland (even though it is still a relatively narrow part of Northland) than Auckland Airport
and there is good sheltered valleys etc
The issue with the kiwifruit is currently dealt with by using a chemical spray to artificially trick the plant into thinking it's had the chilling period. But since ththis chemical has been banned in a few countries already, the writing might be on the wall for northern kiwifruit growing.
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Jeremy B

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igaquo1
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Re: Winter Chill Hours

Unread post by igaquo1 »

NZstorm wrote: Sun 05/07/2020 08:49 There is some steep hill country in North Auckland which will aid frost. I can imagine Warkworth being a cold spot in winter.

I am guessing Avocado is the same as citrus and does not need any winter chilling.
Avocado is a sub-tropical fruit, so you're right no chilling required.
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Jeremy B

Kiwi from Auckland, living in London and watching NZ weather from afar. Occasionally back in Auckland and Tauranga.
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