The Tropical Fruit Forum

Citrus => Cold Hardy Citrus => Topic started by: Millet on May 21, 2014, 04:03:49 PM

Title: How Cold Can My Citrus Tree Sustain?
Post by: Millet on May 21, 2014, 04:03:49 PM
This is a question which everyone has, but is the hardest question to answer.  With citrus trees, this can be even more difficult to answer than for other plants.  Although citrus, like all plants, have definite limits to how much cold they can take, where that line is drawn depends upon not only the lowest temperature reached but also the duration of the freeze, the size and health of the tree, how well watered the plant is preceding the freeze, micro-climates, and what mechanical protection is used in the landscape.  (Taken from the booklet "Hardy Citrus For The Southeast)- Millet
Title: Re: How Cold Can My Citrus Tree Sustain?
Post by: Tom on May 21, 2014, 07:03:38 PM
I would have to add a lot depends on the temps in the recent past. Here we can have 80* F in December and a hard freeze only days later when a cold front comes through. That can be a recipe for disaster. Tom
Title: Re: How Cold Can My Citrus Tree Sustain?
Post by: Triloba Tracker on June 12, 2014, 03:55:28 PM
Makes sense
Title: Re: How Cold Can My Citrus Tree Sustain?
Post by: Pancrazio on June 12, 2014, 07:54:03 PM
I would have to add a lot depends on the temps in the recent past.

This. I think this is the a major factor. Cold acclimation may be a bit hard to achieve but many citrus really need it to express their full potential. Also, i do think that this may be the cause why sometimes we see discrepancies in anecdotal reports on cold hardiness of citrus species.
Title: Re: How Cold Can My Citrus Tree Sustain?
Post by: Scott_6B on June 13, 2014, 08:00:52 AM
Yes, the temperatures in the weeks before a hard freeze are critical in determining how well the trees will respond.

Here is an excellent article about the relationship between cold acclimation and hardiness of citrus trees using field data from FL. 

http://fshs8813.wpengine.com/proceedings-o/1984-vol-97/33-36%20(YELENOSKY).pdf (http://fshs8813.wpengine.com/proceedings-o/1984-vol-97/33-36%20(YELENOSKY).pdf)

Figure 2 in the article is particularly useful as a guideline to determine if your citrus have accumulated a sufficient number of hours of temps below 50F but above freezing to induce full cold hardiness.  For my outdoor trees here in MA (and since I provide minimal heating for them during the winter), it is critical that I know my trees are fully hardened off before allowing them to experience temps in the low 30's F or below. 

Also, there is significant evidence with citrus that even cold acclimated trees will loose a significant portion of their hardiness during subsequent cold spells that occur after the first round of temps in the 20's or below.  In addition to the absolute low temperatures, this is likely one of the primary reasons citrus do not grow well further north where winters last significantly longer (i.e. there is s significant probability of multiple cold snaps per winter) without a good deal of help.

Title: Re: How Cold Can My Citrus Tree Sustain?
Post by: Millet on June 13, 2014, 10:05:21 AM
After a citrus tree has accumulated sufficient resistance to cold weather, it takes only a warm spell of just a few days to once again lose its the cold resistance that it had formally built up. - Millet.