Preparing outdoor citrus for winter

Discussion in 'Citrus' started by Gregn, Sep 30, 2006.

  1. Gregn

    Gregn Active Member 10 Years

    Messages:
    212
    Likes Received:
    0
    Location:
    North Vancouver
    I live in the Vancouver (Zone 8) area and have several hardy citrus varieties growing outside (in ground). My plants are still young and I want to give them the best chance for winter survival. Much of the information on the net is applicable to areas like N Florida, the south east USA and northern Texas. It is my understanding that the climate in these areas is good for citrus with the exception of the occasional arctic blast which may blow through these regions from time to time. Also, daytime heating can cause temperature spikes.
    In the Vancouver area, our typical winter temperatures range from -3c (26f) overnight to up to 10c (50f) (yes we do get the occasional arctic blast where temperatures will get down to -10c but these spells are rare, perhaps every 5 years and when they do they are short lived and are NOT the purpose of this thread. Heavy protection is then required) The sun here is also lower in the sky.
    So the questions, I have are:
    At what temperature is there a danger of triggering new growth?
    Is covering up the plants (mini cold frame) with poly a good idea?
    At what temperature would the use of supplimental heat (like christmas lights) be a good idea?
    Is the use of mulch, leaves straw etc, around small citrus plants reccomended.
    The varieties I have outside are:

    Thomasville citrangequat:
    St Anne satsuma (on trifoliate)
    Yuzuquat (on trifoliate)
    Meyer lemons ( ???)
    US 119 hybrid (on trifoliate)
    Juanita Tangerine (on trifolite)
    10 degree tangerine (rooted cuttings???)
    Poncirus trifoliata
    Flying Dragon (p.trifoliata)

    When should I start fertilizing again? March? or ??
    At what temperature is citrus fruit damaged from frost?

    From what I understand the flying dragon and the poncirus will be ok without protection. all advise is appreciated.

    Thanks, Greg
     
    Last edited: Sep 30, 2006
  2. Millet

    Millet Well-Known Member 10 Years

    Messages:
    1,698
    Likes Received:
    5
    Location:
    Denver,Colorado USA
    Fertilize again in March. Citrus have absolutely no growth at all below 55.4 F (13C). 55.4F is absolute zero for citrus. I would use CHRISTmas lights at any temperature below 32F (0C) just to be safe, even though many of the varieties you mention, can withstand temperature below 32F. Use lights especially if the cold spell is going to be extended. I would not use mulch, but if you do, do not let the mulch touch the trunk of the tree. You will be encouraging many citrus diseases and mice damage. Graig good luck with your trees. I think you will do an EXCELLENT job this winter with you citrus, due to your knowledge, and your love of citrus. Besides, you live in God's country. Try COLD Colorado. Take care. - Millet
     
  3. Gregn

    Gregn Active Member 10 Years

    Messages:
    212
    Likes Received:
    0
    Location:
    North Vancouver
    Thanks millet for your advise. What about the poncirus (sour orange) plants. Since they are deciduous is there a problem leaving them un protected? My Flying Dragon seedling is about 5 or 6 years old - apparently . Also, since absolute zero for citrus is 13c, any temperatures up to that should be OK without triggering new growth - correct?
    I am flattered by your comments.... I like and agree with your CHRISTmas light idea.
    What about watering? Watering the plant before a freeze defies my logic - having frozen ground around a plant doesn't make sense but that seems to be the conventional wisdom
    of hydrating a the plant before it gets stressed by the cold.
    Thanks again
    Greg
     
  4. Millet

    Millet Well-Known Member 10 Years

    Messages:
    1,698
    Likes Received:
    5
    Location:
    Denver,Colorado USA
    Greg, Poncirus (trifoliata) is not a Sour Orange. Sour Orange is Citrus aurantium. Yes, any temperature at or below 55.4F will not produce any growth what so ever on any citrus variety. Flying Dragon should not require any protection at all in the BC area (you guys are Florida North).... If you give your trees protection with Christmas lights (the large Christmas lights, not the little tiny ones) during the light freezes that Vancouver normally gets you should not have to worry about spraying water on the trees to protect them. On cold windy nights you also might have to wrap the trees with some sort of cover plus the lights. This winter, during a late Colorado freeze of 20F (-7C), a friend of mine lighted and wraped an Asian Pear tree that was in bloom. The blooms were saved and set a good crop of fruit. When your trees get some height to them and begin to produce a nice crop of orange colored fruit, they will be quite an unusual sight for the people of Vancouver to behold. Way to go. - Millet
     
  5. leapfrog

    leapfrog Active Member 10 Years

    Messages:
    58
    Likes Received:
    4
    Location:
    Crescent Beach (South Surrey) BC Canada
    Gregn: We're in this together, though I don't have near the range of citrus plants you do! As you know, my single inground citrus is (so far at least) a thriving meyer lemon, which will also winter for the first time this year. I'll keep you posted over the winter and perhaps we can share what works and what doesn't.

    Millett, I'm intersted in your advice in response to Greg's question about the efficacy of covering the plants with a mini cold frame. While I live in the same region as Greg, I'm actually at 48 degrees 25 minutes of latitude vs. 49 degrees and about 20 minutes in Greg's case. While this doesn't sound like a lot, a degree of latitude can make a fair difference this far north, particularly where critical winter lows of 0 C are concerned.

    In addition, elevation makes a big difference. (North Vancouver covers land from sea level to about 2,000 ft in elevation. I don't know your altitude, Greg, but I'm assuming you're nearer sea level than the upper reaches.) I'm right at sea level here in Victoria. My tree also has a wind protected SW exposure, and is in a zone 9a micro climate. The minimum temperatures in this part of the garden for each month of last winter were plus 0.6 C in November, plus 0.4 C in December, plus 2.7 C in January, minus 1.1 C in February, and minus 0.7 C in March. This was about the same as the previous winter. Another mild winter is forecast.

    Here's a thread which includes a picture of the min cold frame I'm referring to:

    http://www.botanicalgarden.ubc.ca/forums/showthread.php?t=16982

    Given your comments about new growth, Millet, I'm also a little concerned about daytime heating on mild winter days, where the temperature can exceed the critical 13 C even without the additional heating created by a cold frame. I expect I'll be fussing quite a bit with mine; opening and closing the door, removing it entirely. Also, while cold spells do not usually arrive overnight, the temperature can easily drop 10 C over a period of 24 to 48 hours.

    I'd really be intersted in your additional comments.
     
    Last edited: Oct 1, 2006
  6. Gregn

    Gregn Active Member 10 Years

    Messages:
    212
    Likes Received:
    0
    Location:
    North Vancouver
    Yes ! This will be interesting. I will have to work out the logistics of warming the trees with the large lights. Some of my trees are very small the others are just small...hmm.
    The row of 3 on the s. side of my house under the eave will be easy, the two in the front will be ok too but two plants on their own will be a challenge...since no string of lights is small enough to hang on a tree. At this point the in ground plants range from
    10" to about 28" in height. I received a runt 10 degree tangerine which did not like the nursery pot it was planted in after being shipped bare root (the leaves were wilted permanently and I didn't think it was going to make it so as a last ditch effort I stuck it in the ground between Two T.Fortunei's and a yucca - It liked its new spot in the ground and is thriving but its only 10 to 12" tall - maybe. It set bloom in august - go figure. No way of putting large lights on it will have to come up with something else.
    Adding up the wattage of the string of mini incandescent lights plus a mini cold frame 12x12Wx15h I wouldn't think it would freeze during a severe overnight frost of lets say -3 or 4c Or use a single 15 or 25 watt bulb??
    It will much easier once my trees are 4 feet tall !!!
    Greg
     

Share This Page