Hello All,

I have a small question about low temps now that my overnights are getting nippy. For about a week now, I have been bringing my citrus' inside, the temps have been flirting with 10°C or lower. But then I read today that containerized citrus should be brought in only if it's going to below zero for more than 4-5 hours.....is this right?? (Seems extreme!). And if so, tonight they are inside (it's 9°C) so forget about it, but tomorrow should be a high of 18°C (no sun predicted) and a low of 13, and that low for the next three days. Should I leave them out tomorrow night and follow the below zero rule from then on? Will I be shocking them now that I've been poopooing them with 22 degree nights indoors? Also, I live right on the St-Lawrence river/seaway, my nights can read a certain temp, but with wind and humidity it feels much colder quite often, Is this a big factor for them?

This brings me to another question for Millet since it is from him I learned of this. I believe you said they should spend, what was it , the equivalent of about a month and a bit under temps of 20°C or below in order to promote budding sites for the next season....(I know you gave it in hours but ...). If I remember correctly, you said this should be approx between nov and xmas ( I could be wayy wrong here, I read this last spring from you). Assuming my recollection isn't shabby, my question is, do those hours of 20 and below must be between nov and dec? If I do leave them out now in temps going to 5 and lower until I really have no choice but to bring them in does the same budding site promotion occur even though it's too early? Could I "trick" them because my season is shorter than most of yours?


All advice is always and much appreciated!

Thanks guys.

Citrus nurseries here in the UK say you should not let the temperature get below 5 degrees C and some say 7 is better.

I've also been told you shouldn't let temperature rise or fall too quickly and keep changing the conditions.

But, I've also read on this forum from people who know better than I do that to get the best out of the trees, constant higher temperatures are better.

We've had night temperatures down to about 7 on a couple of nights 2 weeks ago and temperatures are regularly down to 10.

I've still got most of my trees outside and just a couple of Kumquats in a greenhouse but that's more to stop them getting too wet in the rain.

I overwintered my trees at a minimum of 5 degrees last year but my limes suffered a bit because of it so will increase the temperature a bit this year.

Gen, I don't know where you read that you can leave your citrus outside in temperatures below 32F (0C) but I certainly would not do it. I think you will wind up with dead trees. Keeping your tree at or below 68F (20C) for 850 hours is a method to increase blooming. Water stress is another method. Using the temperature method (the much better method in my thinking) should be done just before your expected blooming period. After the tree has accumulated the "required" time, raise the temperature and the tree will soon begin to bloom. Kumquats and trifoliate excepted. - Millet