UBC Botanical Garden Forums  

» UBC Botanical Garden


Go Back   UBC Botanical Garden Forums > Archives (no new threads) > Citrus

Post New ThreadReply
 
Thread Tools
  #1  
Old July 28th, 2009, 10:39 PM
Deneb1978 Deneb1978 is offline
Registered Plus (3-99 posts)
 
Join Date: Sep 2004
Location: Burnaby
Posts: 96
Lowest temperature for citrus

Hi all,

I am wondering what is the lowest temperature experienced by a citrus hybrid plant and for how long (excluding Poncirus trifoliata)? Maybe we could start a citrus industry here in Canada and produce commercial marmelade :)
Reply With Quote
  #2  
Old August 2nd, 2009, 07:56 PM
Millet Millet is offline
Generous Contributor (100+ posts)
 
Join Date: Oct 2005
Location: Denver,Colorado USA
Posts: 1,699
Re: Lowest temperature for citrus

The question arises as to how much cold a citrus tree will stand. There is no one temperature that becomes the fatal temperature. Although citrus tree can survive temperatures below freezing (32F or 0C), freezing should be considered the lowest "safe" temperature. A fatal temperature for a citrus tree is influenced by many factors, principally by the state of dormancy of the tree, the variety, soil and moisture conditions, the duration of the cold, and the weather conditions immediately preceding the cold snap. The first effect of cold appears on the leaves, the cold gives them a dark greasy appearance. It often happens that the injury is to leafage only and the twigs remain uninjured. Such trees, however, bear no fruit the following season. The resistance to freezing of branches becomes less and less as the branch decreases (smaller) in size. Large branches are injured only by intense cold, and the top of a tree maybe killed back by a freeze before the large branches are affected. The exact degree of injury to the twigs and branches cannot be determined until some time after the frost occurs. No part of the tree can withstand lower temperatures than the trunk can. As with the branches, the trunks resistance to freezing is in direct relation to its diameter. For some time following frost/freeze injury it is IMPOSSIBLE to determine how much pruning should be undertaken. Cold damage usually occurs in December, January and February, and new sprouts do not arise from uninjured branches until spring growth begins. If the injury is severe it may be much later. Only when the tree has been so severely injured as to leave but little of the trunk, it is best to cut it off at the ground. But on the other hand, if a considerable part of the trunk remains uninjured, the upper portion only should be cut away. - Millet (1,263-)
Reply With Quote
  #3  
Old August 4th, 2009, 09:55 AM
Gregn Gregn is offline
Contributor (30-99 posts + 20 days registered)
 
Join Date: Jun 2005
Location: North Vancouver
Posts: 212
Re: Lowest temperature for citrus

Deneb1978, Lets put it this way- this past winter here in North Vancouver we did not have a significant frost until it suddenly plummeted to -12c (10f) around December 17 or 18 2008. My unprotected citrus did not make it through the winter, nor did many of my palms and some other plants that are supposed to be hardy to much lower temperatures. I even completely lost some citrus including the trifoliate orange root stock. Go figure ? I suspect the reason is as millet describes that the plants were not hardened off before the big freeze. In another thread you ask about the best hybrid for Vancouver? I am working on that. I currently have over 30 varieties of citrus. I am hopeful of the following: Sudachi, Various citrumelos, Morton citrange, changsha mandarin and the CiClem24. That being said, my best performers by far are my Meyer lemons. Hands down. My Meyers were planted in the ground In May of 2006 in a full sun eastern exposure. I believe they were rooted cuttings.

In addition to lowest temperatures citrus can tolerate, just as important for growing citrus in climates such as Vancouver are spring and summer temperatures. Without some sort of greenhouse and or cold frame set up you will not attain sufficient growth to produce much if any fruit. At least on younger trees - to start. Acidic (sour, tart) do not require as much heat to ripen so they are better bets if your long term goal is to reap the fruits of your labour.

This is where the Sudachi comes in. They are a small key lime like fruit (sour) which should be harvestable before the end of October and the first traditional frosts here in the Vancouver area. The trees, once mature should (but i don't know first hand yet) survive or winter weather as the trees are hardy to -10 to -15c (but for how long - a hour? a few hours?? a day?? ) They may not take a week of below freezing temperatures without protection.

Just like buying a house, where you plant your citrus is all location, location and location. And of course your dedication and TLC :).

Greg
Reply With Quote
  #4  
Old August 4th, 2009, 12:38 PM
Deneb1978 Deneb1978 is offline
Registered Plus (3-99 posts)
 
Join Date: Sep 2004
Location: Burnaby
Posts: 96
Re: Lowest temperature for citrus

Hey Millet and Greg,

Thanks for the wealth of information you provided. As a subtropical genus of plants, I realize that growing Citrus is a challenge to say the least here... I was just kidding about the commercial marmelade industry up here. I know it isn't feasible...but I think the idea of growing your own lemons around here for personal consumption is great. I know generally with our summers being somewhat cooler (although this year being an exception!), sweeter varieties of citrus don't have a chance to develop. In any case, I'm sure every few winters, they will need a little help even with the hardiest varieties. If you have any lemons that you grew locally outside here, I would definitely be interested in buying a few off of you just to see how they taste....I'd like to tell all my friends that I ate a lemon grown on Canadian soil :)
Reply With Quote
  #5  
Old August 4th, 2009, 12:57 PM
Millet Millet is offline
Generous Contributor (100+ posts)
 
Join Date: Oct 2005
Location: Denver,Colorado USA
Posts: 1,699
Re: Lowest temperature for citrus

Gregn, your assumption as to why your unprotected trees did not survive the winter blast, due to their not being hardened off before the big freeze, is certainly correct. If Trifoliate Orange is not gradually hardened off before a hard freeze, it is no more cold hardy than any other citrus variety. - Regards Millet (1,261-)
Reply With Quote
  #6  
Old August 4th, 2009, 01:13 PM
Ron B Ron B is offline
Ardent Plant Enthusiast (10000+ posts)
 
Join Date: Aug 2004
Location: Edmonds, WA USA (Z8)
Posts: 18,427
Re: Lowest temperature for citrus

All plants have a minimum temperature below which they are always damaged. Where there is a sliding scale is when specimens in less suitable locations do not achieve their full hardiness and are then hurt by temperatures above their actual cutoff point. The main problem in being ready for winter hot climate plants will have in Vancouver is the lack of heat in the summer maturing growth. Dec. 17th is too late for a plant to not be ready for winter that would otherwise be if there had been frost before then. If there had been hard frost before then, a plant not ready by Dec. 17th would have been damaged by that frost just as it was affected by the cold on Dec. 17th.

In addition to lack of summer heat cold and heavy soils are also liable to produce problems with marginal plants, that might come through if growing instead in a warm and light soil.

Citrus will not be important at this latitude primarily because most are not hardy in the north. It will certainly not be for lack of people trying to get them to persist here.
Reply With Quote
  #7  
Old August 4th, 2009, 02:51 PM
Millet Millet is offline
Generous Contributor (100+ posts)
 
Join Date: Oct 2005
Location: Denver,Colorado USA
Posts: 1,699
Re: Lowest temperature for citrus

Ron B wrote:------ "All plants have a minimum temperature below which they are always damaged. Where there is a sliding scale is when specimens in less suitable locations do not achieve their full hardiness and are then hurt by temperatures above their actual cutoff point."

Actually there is a sliding scale in warm locations such as Florida, where citrus have plenty of heat units during the growing season, to fully mature their wood. However even in Florida (and Southern California) cold temperature tree damage to citrus often occurs at a rather wide range of temperatures. This is, of course, due to the many factors that contribute to a citrus trees hardiness, as stated above. - Millet (1,261-)
Reply With Quote
  #8  
Old August 5th, 2009, 08:55 AM
Gregn Gregn is offline
Contributor (30-99 posts + 20 days registered)
 
Join Date: Jun 2005
Location: North Vancouver
Posts: 212
Re: Lowest temperature for citrus

Deneb1978, Earlier in this thread, you mention marmalade. My late father used to make his own marmalade (of course not from his own home grown citrus fruit :) I remember the kitchen was mayhem on those Saturday mornings...

Given a couple more years I hope to make my own marmalade from my home grown fruit. (Mind you, at the rate my Chinotto (sour) oranges are growing it may be longer that that if I want to use them as the main ingredient)

Bob Duncan on Vancouver island has local restaurants requesting his fruit (including citrus) for promoting the 100 mile diet. If you get a chance you should take a look at his operation - he has large specimens of many citrus cultivars loaded with fruit - an inspiration to anyone who likes to grow outsize of 'the zone'. He offers tours of his nursery by appointment.

http://www.fruittreesandmore.com/

Greg
Reply With Quote
  #9  
Old August 5th, 2009, 06:15 PM
thesun thesun is offline
Registered (1-2 posts)
 
Join Date: Aug 2009
Location: boston, ma, usa
Posts: 2
Re: Lowest temperature for citrus

Does anyone know if citrus trees (I'm growing a Japanese "bontan" (overgrown, ugly grapefruit) and "clementine" orange tree) will survive year round if planted on Cape Cod? We rarely dip below -15 deg C, but it's often between 0 and -10 for a week at a time during the winter. I currently have them in pots and bring them inside each year, but I'd love to plant them...if I could be sure they'd be okay. I'm not worried too much about the fruit or whether they flower...I just want them to be able to have a fighting chance of survival if I plant them and they're outside all year.
Reply With Quote
  #10  
Old August 5th, 2009, 09:33 PM
Gregn Gregn is offline
Contributor (30-99 posts + 20 days registered)
 
Join Date: Jun 2005
Location: North Vancouver
Posts: 212
Re: Lowest temperature for citrus

Thesun, I am not sure about your "bontan" but I would say no way- or at least highly unlikely your "clementine"would survive -15 without significant protection. What I would pursuit is a specimen of a Ichang papeda. It is genetically a true citrus plant which is unfazed of -20 c. Though the fruit is not edible, it is a wonderful specimin to have and a great conversation piece for the garden (that is what we all of us really enjoy - right?)

This link has very good information on the papedas and some of their very cold tolerant hybrids. (some are naturally occurring...)

http://users.kymp.net/citruspages/pa...ml#ichangensis

These are the best and most cold tolerant of the true citrus hybrids - they are not cross bred with the trifoliate orange.

Of course there are the anomalies of some of the seedlings people have planted like the "Juanita tangerine' surviving 0f ( -17c) the 'Croxton Grapefruit" 12f (-10c) etc. For some reason seedling grapefruit are known to take much lower temperatures than the parent trees - why ??? - I cannot answer that - I will leave that to the experts...

Greg
Reply With Quote
  #11  
Old August 24th, 2009, 10:37 AM
frankmass frankmass is offline
Registered Plus (3-99 posts)
 
Join Date: Jun 2008
Location: massachusetts
Posts: 11
Re: Lowest temperature for citrus

Thesun, I am in mass and grow a fair amount of citrus, all recieve a lot of protection in the ground.... Your better off protecting something and getting a tree that is somewhat edible,,,,,
Reply With Quote
Post New ThreadReply

Bookmarks

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are Off
[IMG] code is Off
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
max temperature for tomatoes earlquick Fruit and Vegetable Gardening 0 June 10th, 2009 06:15 PM
Today's Temperature Acoma Fruit and Vegetable Gardening 12 May 19th, 2009 05:25 AM
Leaf Temperature Junglekeeper HortForum 6 October 22nd, 2005 05:49 PM
Safe Temperature? GreenLeaf HortForum 2 October 21st, 2005 12:34 PM


All times are GMT -7. The time now is 11:34 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Copyright 2001-2011, University of British Columbia Botanical Garden & Centre for Plant Research