For citrus growing in a controlled environment such as in a greenhouse where the temperature can be regulated, what are the advantages and disadvantages to keeping the temperature high enough (> 13C/55F) to avoid plant dormancy? Obviously one would get continued growth by incurring additional cost for heating but what about from the plant's perspective?
There are temperatures that are considered a must. For example 55.4F (13C) is "absolute zero" for citrus roots. Citrus roots at or below 55.4F cannot and do not function at all. Therefore cannot send water to the foliage when needed. Currently I am growing 52 different citrus varieties in a large greenhouse in Colorado. I want, as probably most everyone does, all the vegetative growth, and also all the fruit production that the tree can give. So I grow my trees so that the root system is kept at or above 64F during the winter months, which gives optimum root function, and the foliage as warm as reasonably possible (75/85F) during the day with a minimum of 55/60 nights. This will encourage growth. However, citrus flowering occures because of stress to the tree. the most common stresses are cold/cool temperatures in subtropical areas, or drought in pure tropical areas. So from November until approximately Christmas, I reduce the day temperatures to approximately 60 days and 55 nights. Citrus require 850 hours of cool temperatures to produce a good bloom. For small trees or seedlings where only foliage growth is wanted then temperatures of 85F day 60F night would be good. - Millet
Hi, Millet. Would it then be safe to say there is no drawback to avoid dormancy based on your experience? Come to think of it, in the tropics where citrus can be grown, does it ever get cold enough to induce dormancy? If the answer is no, then dormancy is not necessary. OT: Do you ever get theft of the oh-so-tempting, tasty fruit? ;)
Junglekeeper I basically asked the the same Q on another fourm if citrus needs a time of rest. Very good Q Hope you post an answer, I will do the same
Citrus being an evergreen plant never actually becomes"dormant" like apples, cherries and peach trees. Citrus are grown the world over in many areas that never get cold enough to cause citrus to become "dormant". Places such as South Africa, Brazil (the world largest citrus growing country), Cuba, Columbia ect. If you reduce the temperatures to much during the winter months in your greenhouse, the fruits stop growing (below 13C - 55.4F) and the fruits then mature as a small size fruit. Oranges grown in the tropical countries like Cuba and Columbia are a lot larger in size when mature than are California or Florida fruit. Also when grown at higher winter temperatures citrus fruits mature much faster. A Wasington Navel orange in truly tropical Columbia takes 6 1/2 months to ripen, in sub-tropical California a Wasington Navel Orange requires14 months to become ripe. - Millet
