Minimum overwintering requirementsfor citrus

Discussion in 'Citrus' started by MamaMac, Aug 29, 2007.

  1. MamaMac

    MamaMac Active Member

    Messages:
    74
    Likes Received:
    0
    Location:
    Millet,Canada
    I am planning on eventually building a conservatory, but due to the INSANE building costs at the moment, have decided to put it off for a while. I have a citrus cocktail tree(Meyer lemon, and Key lime), a Calamondin orange, and many seedlings of various oranges. My question is this: Would they be better off in a minimally heated greenhouse, or inside the house under lights? I know that it may seem early to be preparing or winter, but we had a touch of frost last night already!
     
  2. skeeterbug

    skeeterbug Active Member

    Messages:
    826
    Likes Received:
    10
    Location:
    Pensacola, USA
    There are two options for getting citrus through the winter in good shape.

    1-Keep the roots warm ( at least 65 F) and give the tree some light (a bright window is sufficient).

    2-Keep the tree out of direct sunlight and let the roots cool, but maintain overall temp above 40.
     
  3. MamaMac

    MamaMac Active Member

    Messages:
    74
    Likes Received:
    0
    Location:
    Millet,Canada
    I don't know if I can heat my greenhouse that warm, so if I bring them inside, (where they were last year) would you recommend a bright window, or I have grow lights downstairs. Thank you very much for your reply, you are one of my favorite posters!
     
  4. Millet

    Millet Well-Known Member 10 Years

    Messages:
    1,698
    Likes Received:
    5
    Location:
    Denver,Colorado USA
    You can put the tree anywhere as long as you keep the foliage (scion) and the root system balanced. If the tree is in front of a warm sunny window, then the roots must be kept at 65F>, if the tree is kept in a low light area than the entire tree should be kept at least 40F to avoid the possibility of damage. If the tree is under grow lights, then I would recommend that the roots be maintained at 65F+ - Millet
     
  5. MamaMac

    MamaMac Active Member

    Messages:
    74
    Likes Received:
    0
    Location:
    Millet,Canada
    Thanks very much both of you. As I said, they were both inside for the winter last year, and the Cal had a bumper crop (made Calamondin nut bread, MMMmmm), the Meyer lemon part of my cocktail tree did fine, but the key lime part dropped all its leaves and sulked until it went outside. It finally has new leaves and now I have to move it! (poor thing). Are their requirements that different? Or am I destined to have a half lemon/half stick tree?
    P.S.
    Millet you are a Citrus God. I actually live in a town that is your namesake!
     
  6. skeeterbug

    skeeterbug Active Member

    Messages:
    826
    Likes Received:
    10
    Location:
    Pensacola, USA
    Key limes do not like temperatures of 40F or below. I would recommend that you get a thermometer that you can put in the soil to accurately measure temperatures in the 50 -70 F range. Most people think that because the room is heated to 68 or 70 that the soil in a container is the same-- that is not so. There are several factors that cool the soil well below room temp-- a thermometer is the only way to know.

    Skeet
     
    Zeit likes this.
  7. Millet

    Millet Well-Known Member 10 Years

    Messages:
    1,698
    Likes Received:
    5
    Location:
    Denver,Colorado USA
    Mama, after reading your post, I went to Goggle Earth, and plugged in Millet, Canada. I see that Millet is south of Edmonton and Leduc. I bet Millet, Canada is a nice town. Is it winter wheat, millet and other cereal grain country around there? Edmonton, is my second favorite Hockey team, behind the Colorado Avalanche. Good luck with your tree. - Millet
     
    Zeit likes this.
  8. MamaMac

    MamaMac Active Member

    Messages:
    74
    Likes Received:
    0
    Location:
    Millet,Canada
    Skeet- I will definitely buy a thermometer for my cocktail tree. I did make the assumption that the soil temp would be adequate due to the room temp, Maybe that is the problem.
    Millet- yes it is cereal grain country here. Millet is a very picturesque town. Colorado is my second favorite team, behind Edmonton!
    Thanks again both of you. I'll let you know if it still decides to have a tantrum.
    P.S.
    Go Oilers Go!
     
  9. mr.shep

    mr.shep Well-Known Member 10 Years

    Messages:
    1,424
    Likes Received:
    23
    Location:
    San Joaquin Valley, California
    Yes, Limes are more sensitive to cool conditions
    than the Calamondin and the Lemon will be. One
    of the reasons why we do not see Limes used much
    as a rootstock any more was due to the behavior of
    trees (denuding) that do get some cold chill. If it is
    any help, all but the Bearss and Palestine Sweet Limes
    lost most of their leaves last year. My Kaffir Lime
    lost all of the leaves and the misses Kaffir Lime lost
    all but four, the four that were covered and protected
    by the nearby Bearss Lime. The Mexican Lime lost
    all of its leaves and then threw out leaves and flowered
    during the coldest part later - makes no sense but it has
    done this two years in a row to lose the leaves when it
    first got cold and then came back with a flush of new
    growth during the coldest part of the Winter later and
    endured that cold just fine.

    I think Junglekeeper has your problem somewhat solved
    by his commenting on using a heat blanket under the
    container. Not so sure the Calamondin or the Lemon
    will need it but the Lime probably will to hold it over
    until you can set this tree outdoors again. It is the
    Lemon that is more apt to balk at direct window light
    or ambient light hitting the leaves and not the top of the
    soil in the container when indoors. Sometimes we
    just have to endure the Lemon losing a few leaves
    because of it until the plant gets some age to it. As
    time goes by the Lemon part of the tree will try to
    adapt to your conditions after you bring the tree back
    indoors or under shelter. At least you will not have
    to worry about cold winds hitting the leaves and in
    that respect protecting the Lemon when cold will
    pay off for you later.

    I'll stay out of the Hockey team preference for a
    brief second --- until now - Go Sharks!

    Jim
     
    Last edited: Aug 31, 2007
  10. MamaMac

    MamaMac Active Member

    Messages:
    74
    Likes Received:
    0
    Location:
    Millet,Canada
    Mr. Shep- Thank you so much for your comments. I have the Stanley Cup Champions of Citrus helping me here. Truly appreciative. Are the limes that you are talking about container grown, or are they in the ground? Would I then be best off to put the cocktail tree downstairs under grow lights and on a heat mat? That might keep both the kids happy. The lime would have warmer soil, and the lemon would have light on the top of the soil, instead of just on it's leaves right?
    Any opinions as to if it would be better to bring it inside now, before I really need to, or to put it in the greenhouse until temps start to drop and I need to start heating it? Is there any overwhelming benefit of one over the other?
    The lemon part has about 7-8 lemons on it with one being 3/4 grown. Having read many of your combined threads on fruit drop, I know that it is normal for quite a lot of blossom and fruit to drop. Is there any way to increase the chance that the most mature fruit will not drop when I move it wherever it ends up? I assume the stress of re-adjusting to a new temp, light, humidity etc. will stress it into some fruit drop, or am I being pessimistic?
     
  11. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

    Messages:
    5,803
    Likes Received:
    505
    Location:
    Vancouver BC Canada
    I don't do anything special for my trees in the winter. You must be recounting my experiment using a heat mat to help a lemon tree recover from root rot.

    The minimum temperature in my unheated plantroom was around 6C/43F last winter. The trees are exposed to bright sunlight throughout the day in high humidity. They appear to be quite happy (or at least they're not complaining) under these conditions. I've not noticed any difference between soil and room temperatures. The thin layer of carpeting between the concrete and container, together with low air circulation (thus minimizing the cooling effect) may be the reason.

    My observations seem to contradict those of my esteemed colleagues; I have no explanation other than what I've provided.
     
  12. MamaMac

    MamaMac Active Member

    Messages:
    74
    Likes Received:
    0
    Location:
    Millet,Canada
    Very interesting Junglekeeper! I am planning on heating my greenhouse to between 5-10C. Perhaps I shall do a little experiment with some of my seedlings. Did you grow the plants you are referring to from seed? If so, maybe they inherently know that they are Canadian citrus and just have to suck it up, as they will never know more hospitable climes!?
     
  13. mr.shep

    mr.shep Well-Known Member 10 Years

    Messages:
    1,424
    Likes Received:
    23
    Location:
    San Joaquin Valley, California
    One of my oldest online friends lives near Camrose.

    The Limes I referenced are all in containers and
    are all grown outdoors in pretty much unprotected
    settings. I did put my Kaffir Lime under cover facing
    due West and it endured the cold January temperatures
    well at the time but a week later the cold winds coming
    from the Northwest did the real damage to the tree. I
    have leaves allover the tree now but will place it due East
    under protection from a front patio next to the Palestine
    Lime I have here this Winter. I am a little cooler than
    where the misses Citrus are just 60 miles down the road.
    I can be as much as 6-10 degrees cooler where I am in
    some years.

    I do not like putting Citrus in basements if I can help
    it. I know of some Europeans have in years past in
    part due to no where else to put them to overwinter.
    I like what Millet posted about the leaf and soil temps
    being about the same which does lead to an idea that
    Citrus can endure a basement setting in which the
    temperatures are pretty uniform as opposed to the
    leaves being much warmer than the roots are. We
    cannot fully equate what the Lemon part of the tree
    will do or the Lime part of the tree when we have
    just one rootstock for this tree. It is more likely
    to see leaf drop from both the Lime and the Lemon
    when this tree is moved indoors but that is something
    your tree will better adapt to the longer you have it.
    Once you set up a routine of setting the tree outdoors
    for part of the year and bring it indoors for the cold
    part of the year, eventually your tree should become
    use to it. That is not to say that it will however as
    homeowner trees I've been around do adjust and
    some trees do not adjust too well at first when
    grown indoors but in time I think your tree will
    respond better to it.

    A note about trees. If my trees are to burn up here
    due to the heat or freeze due to the cold I want them
    to do it the first year I have them. From then on the
    trees will adapt better, some may be slow about it
    and some will be adapted by the third year. We can
    expect some leaf drop of the Limes and the Improved
    Meyer Lemon during the Winter anyway. It is when
    we have leaf drop during the actual growing season
    is when I get concerned that my trees are far from
    being happy.

    I do not think the tree is your central issue here but
    the rootstock and how well you care for it will be.
    While indoors you cannot overwater this tree and
    see the droop to the leaves with their "leaf faces"
    hanging down or under water the tree and see the
    leaf faces nod then become erect and then nod
    again about a week later. Either way you hurt the
    roots but you will cause less overall damage to the
    roots if you underwater rather than overwater.

    I like the heat mat for use inside the home as long
    as you have enough ambient light or enough light
    for at least an hour to pass through a window.
    We've seen some Citrus in this forum that got
    little to no appreciable light from a window but did
    get some incandescent light and the trees, although
    leggy, do have leaves that have some size and color
    to them. Kind of amazing that they can but Citrus
    can do well, even in areas that are not well lit
    as long as we do not overwater them. That is
    your biggest nemesis more than anything and
    the reason why is that if you ever get a water
    mold fungus in your root system you may not
    be able to get rid of it inside the home. Outdoors
    is not nearly as problematic as here we are too
    warm and too dry for a water mold fungus to
    ever get established with our outdoor container
    plants. Even when we overwater our trees in
    synthetic soils we still get good drainage and
    we do not have perched water table for any
    length of time. This is precisely why I like
    having the Citrus placed on a concrete slab or
    on bare ground as even three hours after a watering
    here there will not be any water lingering in the
    container where the roots hit the bottom of the
    container. In wetter areas such as much of Oregon
    we can see perched water table in the containers
    all through the Winter until the temperatures get
    warm enough to not allow for any standing water
    in the container. The problem we had with our
    Orchids grown indoors was that we had a perched
    water table in the root zones for too long a period
    of time, thus what kills our Orchids is a root rot.
    What kills many of the Oregon plants is in effect
    a root rot. What is the most damaging thing you
    can do for an indoor Citrus is to give it too much
    water and then use a tray underneath to collect
    the water and then not empty the tray as soon as
    you know all of the water has passed through
    the container. It is not so much the heat or the
    dryness that prevents us from seeing much
    root rot outdoors it is that we have low humidity
    also outdoors that we do not have when grown
    indoors or in a greenhouse and in some cases in
    a coldframe as well.

    Unless you want to better ensure that you will have
    an abundance of fruit, perhaps year round from the
    Calamondin then I would not go overhead lights
    unless you really feel the need to have them. Gina
    can help here, so can Millet and others. For us in
    a greenhouse we were not interested in any flowering
    or fruit development as the displaced or redirected
    energy will take away from the growth we wanted
    from the young plant. We used overhead lights for
    8-10 hours a day in the Winter but as soon as the
    temperatures stayed above 28 degrees they were
    moved out of the greenhouse into an unlit saran house
    and under 50% shade cloth and were watered by
    misting type sprinklers. The trees never got overly
    watered or thoroughly soaked unlike what we do when
    we hose water or water the trees indoors. Then when
    placed outdoors they were watered by overhead sprinklers
    and stayed in containers the whole time. The in ground
    collection of trees were irrigated by modified drip
    systems in between the trees and were watered by
    overhead sprinklers as well, even during the Winter.

    Junglekeeper, I think you had agreement among us
    that your heat mat served a purpose that may be
    real useful for indoor Citrus homeowners. We have
    to realize that many root rot fungus die out when
    exposed to warmth, which is one reason why we
    see less incidence of disease from trees grown in
    the ground in a greenhouse than we do in container
    grown trees in a greenhouse. The roots stay warmer
    in ground.

    Jim
     
    Last edited: Aug 31, 2007
  14. skeeterbug

    skeeterbug Active Member

    Messages:
    826
    Likes Received:
    10
    Location:
    Pensacola, USA
    JK, when you say the trees are exposed to bright sunlight, is that direct sunlight from a southern exposure or diffuse light?

    I know that humidity helps, but I have lost seedlings when exposed to just an hour or so of direct sun (low angle morning sun) while in my shop where the temps were in the upper 40s to low 50s. Humidity down here is almost always above 70 %. Exposure to a cool breeze can also help cool leaves exposed to sun while the roots are inactive, but that can be risky-- I only did that when the roots were close to active and the pots were being exposed to the sun.

    MamaMac, Exposure to several hundred hrs (about 800 I believe) of temps below mid 60 is pretty much the stress that is required to initiate blooms on your citrus. If you bring them in now and keep them above the mid 60s you may not get any blooms.
    Light is only required for growth during the winter, if you only want survival (in good condition) they only need to be kept above 40 and out of direct sunlight.

    Skeet
     
    Zeit likes this.
  15. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

    Messages:
    5,803
    Likes Received:
    505
    Location:
    Vancouver BC Canada
    I did have two seed-grown trees at one point but I got rid of them to make room for cultivated varieties. I've not noticed any difference in the way they grow compared to trees that originated from the States.

    The mat worked for the purpose of the experiment. I'm not sure the outcome would be the same if a larger container was involved. My 8" pot was small enough to fit on the mat - not so a larger container. Also, the distribution of heat is concentrated near the bottom and thus would not work well for the latter. Therefore I believe a string of Christmas lights wrapped around the exterior would be a better method for larger containers. It would also be a much cheaper solution.

    Direct southern exposure behind unshaded windows. The minimum I recorded likely occurred during the hours of darkness. Daytime temperatures are likely to be nearer to the all important 13C/55F level. Perhaps the higher humidity provides a buffer that allows time for the roots to warm up. It would be interesting to keep tabs on the temperature throughout the day this coming winter. I lost a number of rooted cuttings last winter. Perhaps the lack of an established root system was the cause, similar to the loss of your seedlings.
     
  16. skeeterbug

    skeeterbug Active Member

    Messages:
    826
    Likes Received:
    10
    Location:
    Pensacola, USA
    JK, I am surprised that you did not get significant WLD. Maybe you have a cold adapted tree that still has some root activity at 55F.

    I watched my seedlings closely when I put them outside in the sun when the soil temp was close to 55F. Tender new growth would often wilt for an hour or so before perking up as the soil temp increased. I could tell that the direct sun was heating the leaves, misting would often dry in 10 minutes or so on the leaves getting direct sun. The limited experimentation that I have done suggest the 55F limit that Millet has given us is right on.

    Skeet
     
  17. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

    Messages:
    5,803
    Likes Received:
    505
    Location:
    Vancouver BC Canada
    I'm just glad I don't have the problem, for whatever the reason. It would be interesting to know why though; the science behind it certainly seems sound. A closer monitoring of the temperature movement will help in solving this mystery. I wonder if the size of the container plays a significant role in that it would affect the rate of change in temperature of the root system? Most of my trees were in 8" pots. The room itself warms up quite quickly because of the southern exposure. That might also be a factor.
     
  18. skeeterbug

    skeeterbug Active Member

    Messages:
    826
    Likes Received:
    10
    Location:
    Pensacola, USA
    Do the pots get exposed to the sun? That might be a factor if so, often the pots are on the floor below the window sill getting cold air flowing down from the window while the leaves are being overheated. The size of the pot would help some, but most of the roots are near the side and the bottom, so it won't help all that much.
     
  19. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

    Messages:
    5,803
    Likes Received:
    505
    Location:
    Vancouver BC Canada
    The pots are shaded by a 2-foot wall.
     
  20. Millet

    Millet Well-Known Member 10 Years

    Messages:
    1,698
    Likes Received:
    5
    Location:
    Denver,Colorado USA
    But is the tree setting near a south facing window and the foliage in the direct rays of the sun? If not near he window, how far from the glass is the tree? The amount and strength of the sun's rays decreases rapidly with distance from the window. If at the window, how many hours of direct sun is focused on the tree's foliage? Lastly, do you actually know what the soil temperature were during the winter months? - Millet
     
  21. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

    Messages:
    5,803
    Likes Received:
    505
    Location:
    Vancouver BC Canada
    The trees are right next to the windows where they get maybe six hours of direct light between 9am and 3pm from the east and south. The exact temperatures of air and soil are unknown. I plan to take more precise readings this winter. Up to now I've kept an eye mostly on the minimum room temperature but I'm quite sure there are times during daylight hours in which the room is below the absolute zero for citrus. I have not encountered any problems and so have not had a need to track temperatures in detail.
     
  22. Millet

    Millet Well-Known Member 10 Years

    Messages:
    1,698
    Likes Received:
    5
    Location:
    Denver,Colorado USA
    you must water these trees with Holy Water. - Millet
     
  23. Junglekeeper

    Junglekeeper Esteemed Contributor 10 Years

    Messages:
    5,803
    Likes Received:
    505
    Location:
    Vancouver BC Canada
    THAT might have saved my dearly departed Lisbon Lemon which did not recover from its bleeding sap condition.

    It could be that I've just been lucky so far with the combination of factors; the trees have only been through two winters. It's conceivable that it was overcast on the days with the lower temperatures.
     

Share This Page