I'm writing this post concerning the "happy balance" potted citrus need.. Balance between light, root temps, air temps, water, and fertilizer..

Mostly the water happiness will continue to be the same.. "as NEEDED" finger check or what ever method preferred by grower.. But Knowing the rest some times gets a bit fuzzy for those of us with out hort degrees...
I realize that if the tree receives less light the heat requirements will go down.. and if same tree receives more light it will require higher temps.. etc.. and growers have different needs from their trees.. some wish more fruit while others are more concerned with putting on more growth.. and there are a few that are in the middle and would like fruit.. but still want active growth..

Beings our trees are in pots we can control the growing stages of our trees better than those planted in ground.. All we have to do is add more light and boost the heat the tree receives and we have a tree that thinks it is spring and NOT mid winter with snow on the ground.. and then some may add all the extra and not allow for the needed stress to cause blooms in spring and wonder why their tree that they pamper never blooms and fruits for them..
I am also not real clear on canopy/ air temps vs. root temps..

Feel free to fill out one or all of the following question…
Anyone see any details/ questions I’ve missed let me know..
Since there are no real good books on growing citrus in pots I’m hoping this will help me and others that are pot bound citrus growers..

Be they questions or answers all input to this thread is welcome!!!
The first is a general potted citrus.. I added individual categories incase their requirements are different.. I know some citrus grows well in one area but won’t grow as well in another due to climate differences..
Sorry if it is too lengthy…

Please fill in the blanks with Min/max.. if min or max requires X # hrs please indicate in footnotes..


Potted citrus winter Requirements chart...

To achieve Max growth regardless of spring bloom....
# Of Light Hrs required ____ Air temps_____ Soil Temps_____ Fert or No fert? _____
Footnotes _________________________

To achieve canopy growth and Spring bloom....
# of light hrs required ____ Air temps ____ Soil temps ____ Fert or no fert? ___
Footnotes _________________________

Spring bloom regardless of canopy growth...
# of light hrs required ____ Air temps ____ Soil temps ____ Fert or no fert? ___
Footnotes _________________________





Thank you for your time, help and interest!!!

Gina *BabyBlue*


Edited to shorten.. took out individual citrus types..

thanks for all the input!!

Glad you thought of this Gina, being a novice at this and working very hard at it, this chart will be of great help. I am hoping you will share results. It is hard to go and find everything in past posts that you know you read at one time and at this point I am doing all that common sense tells me to do. I am determined to succeed, but will take all the help I can get.

Joan,

Thanks for your interest!!
If I receive any input on this I will post it..

I hope to get a good guide line to go by.. or might just have to move to warmer climate where I can put all my citrus in ground?? LOL

Good luck with your babies this winter!!!

Gina *BabyBlue*

Gina, that was good. Those are questions many of us pot growers have.
I learn more every year, but I'm sure I will do something wrong this winter & leaves will drop & I won't know how to improve till next winter.
I sure hope someone can answer some of this or maybe put things in a nutshell. All I know is, less water in winter. If soil temps are lower than 58*, the plant won't grow , therefor don't fert. And, if the canopy gets a lot of sun, the soil temps have to be above 58* so roots can keep up. Did I get that right anyone?
What confuses me is when ppl like Benny, who gets frost on occassion & low temps at night,...lower than my sunroom, still can ripen his fruits & get blossoms! Is this because he has bigger pots on some & the center soil doesn't get so cold?
Anyway, good quests. I guess anyone to answer could just copy & paste parts & fill in lines. Thanks Gina
Ps, my guava looks very healthy but today I lost the last of 4 babies. I even wrapped & insulated the pot & it's not even freezing outside yet! I don't know what's wrong. Oh well.
I want to fert some that have new blooms & ripening fruits, but soil temps are between 56 -60* & don't know if it'll hurt the plant. If plants stop growing at 58*, why are mine still blossoming & fruits still growing?

There is a comparative temperature difference between citrus species, but the difference is not large enough to worry about. In general at temperatures at or below 54.5F soil and/or air temperature there is very little or no growth of all citrus species. This would be called the MINIMUM growth temperature. The general MAXIMUM growth temperature for all citrus varieties, is 95F. At temperatures at or above 95F little on no growth occurs. The optimum growth temperatures are somewere inbetween the the high and low. For example the growth temperature for grapefruit is given between 68F to 86F, with the optimum somewhere between these points. The minimum and maximum temperatures for calamondin, trifoliate orange and citrange is somewhat higher than grapefruit, being 68F to 95 F., again with the optimum somewhere inbetween. For Oranges the minimum is 55.4F and the maximum is 93.2F and the optimum temperature was found to be 80.6F. These temperatures ARE NOT to be confused with the minimum and maximum ENDURANCE temperatures. Endurance temperatures are the maximum and minimum temperatures at which citrus varieties can survive. The endurance temperatures can be quite higher and lower than the growth temperatures. It should be understood that the minimum, optimum and maximum growth temperatures are relative only, because a great number of variables exists in climate, humidity, water, wind, location and so forth. Under normal conditions the temperatures required for sufficient FLOWER BUD induction, that is, the changing of citrus buds from vegitative buds into floral buds, depends on the previous crop load of the tree. Sufficient flower bud induction should be achieved when total UNINTERUPTED accumulated hours of low temperatures exceed 850 hours below 68 degrees F. (20C) if the current crop load was heavy. If the crop load was lght, sufficient flower bud induction can occur after 750 hours of accumulated low temperatures < 68F. 500 hours of temperatures below 68 degrees F. will usually produce a weak bloom. - Millet

Hi Millet,
If it takes 750 h of uninterupted temps below 68, How can south Florida ever get citrus to bloom? We probably rarely get 30 days of winter here in N Florida where the temp doesn't get above 68. It is very common to have January highs in the low to mid 70's here in Pensacola.

That question aside, I have another question regarding temperature. Now that I have a number of seedlings in containers and we are beginning to get night time temps in the upper 40's, I have noticed several of the seedlings with droopy leaves in the mornings (they are sitting outside on a table exposed to sun). Since I do not have a greenhouse to keep the soil above 55, would I be better off putting these seedlings where they do not get morning sun? And when it starts getting even colder, should I put them where they do not get any direct sun. If so, Should I bother moving them to the sun on those warm winter days when it gets into the 70's?

Skeet

Hi Skeet, of course Florida (even southern Florida) normally gets the required number of cool hours below 68F to achieve flower bud induction. Here are the official records for uninterrupted induction hours <68F for the last four years (2003-2006) for Florida citrus districts from southern Florida to Northern Florida.

2003 - 900hrs. S. Fl. - 1100hrs. Cntrl. FL. - 1200hrs. N. FL.
2004 - 980 to 1200 hrs. from southern districts to northern districts in FL.
2005 - 820 to 830 hrs. from southern districts to northern districts in FL.
2006 - 810 to 1250 hrs. from southern districts to northern districts in FL.
These statistics, plus many additional years can be found at the University of Florida Research Institute. However, your misunderstanding might be my fault for not being clear enough. "Uninterrupted" hours, does not mean that the temperature cannot at any time go above 68 degrees Fahrenheit. What it does mean is the temperature cannot remain warm (75+ degrees) for a 7-12 day period which can break the buds "dormancy" and lead to bud growth. Any bud growth automatically breaks the uninterrupted hours. Skeet, about your seedlings. The reason for the wilt is of course due to the cool temperature of the container's soil. The direct sun on the leaf surface is causing the leaves to call for water from the roots, but because the root system is cold they cannot respond. Either raise the root temperature to perhaps 64F, or remove the leaves from the direct sun, until the soil temperature again rises to a higher temperature. I remember Citrange (UK member) talking about some citrus trees in Europe that were stored down in a dark/cool basement during the winter. Dark and cool = balance. Warm soil and direct sun = balance. Cold roots and direct sun = out of balance. If they were mine, I would move them inside where the soil temperatures would be in the 64F to 70F range, and then I would put them outside during good weather. A lot of people would also do the same, and a lot of people would not bother. Take Care Skeet. - Millet (PS I'll send you a PM about Mr. Shep).

Thank you so much Millet for explaining this again, but more detailed. I'm thinking that in Dec - Feb, I will turn lites off sooner than 8:15pm. All the lites (not a lot) & cool temps won't equal balance. I will let them rest this winter for a GREAT BIG splurge of growth & fruits next year! It'll save me $$$ too.