Black pine dormancy

[Deleted member 53211]

Hi guys

I live in south Brazil where the climate is subtropical, meaning we have very hot summer and temperature drops a bit in winter, to an average of 20-24 degrees celsius. Obviously some days are very cold and others are hotter. I cultivate some black pines here and i would like to know if they go into dormancy during winter here. I heard pines needs a very cold season for it to go into dormancy, so i would like to know if the winter here is cold enough for that.
Also should i keep fertilising my pines during autumn and winter or not?

 

[Wires_Guy_wires]

Japanese black pines grown in Australia have little to no dormancy, but they seem to perform very well.
I think your climate, when it comes to temperatures at least, can be considered similar. Or maybe closer to South Africa or South Asia. I believe JBP doesn't require a full cold dormancy, but rather they do "temporary growth stop" during the colder season.

If they don't actively grow, there's no need for fertilizer.

 

[Deleted member 53211]

Japanese black pines grown in Australia have little to no dormancy, but they seem to perform very well.
I think your climate, when it comes to temperatures at least, can be considered similar. Or maybe closer to South Africa or South Asia. I believe JBP doesn't require a full cold dormancy, but rather they do "temporary growth stop" during the colder season.

If they don't actively grow, there's no need for fertilizer.

I think the climate here is very similar to Florida. This is the best reference i can give.

 

[Shibui]

Very little if any dormant period where you are. I think we already discussed this?
Even here where it gets much colder than Brazil and JBP seem to stop growing for a month or so I get much better spring growth on trees that were fertilized through winter so winter fert is useful.
If you had 2 trees you could try it as I did and see the results first hand.

 

[Deleted member 53211]

Very little if any dormant period where you are. I think we already discussed this?
Even here where it gets much colder than Brazil and JBP seem to stop growing for a month or so I get much better spring growth on trees that were fertilized through winter so winter fert is useful.
If you had 2 trees you could try it as I did and see the results first hand.

Yes you were the one who brought up this to me haha. But you werent so sure so i decided to create a topic about this. Thank you again

 

[Shibui]

Still hoping for confirmation (or not) from some JBP growers in tropical areas????
There's so much experience from growers in cooler climates but very little info from those in warmer areas.

Just went back and reviewed some of the info from the JBP study. The interim conclusions were:
Anyhow, Those who lived in colder climates; (Hobart, Melbourne, hills near Albury, and myself here in Canberra); found that fertilising over winter (liquid ferts) found it to be beneficial and worth continuing. The strongest result was Hobart.

Conversely a grower on North Coast NSW found it unnecessary and contra-indicated(i.e. don't do it). He said the pine he tried it on would not go dormant. I will need more information from him and will see him in 3 weeks at Bonsai By The Beach.

I did not get any participants in QLD so just had to chat with a few growers. They don't fertilise over winter or only low or zero nitrogen. They do however agree that most pines in QLD are severely under fertilised on a regular basis. I had to comment that, unfortunately, about 50% of the pines that were on display at the Gold Coast convention last year were in disastrously poor condition. This is a combination of lack of fertiliser, long growing seasons and severe pest and disease pressure.

They probably need to fertilise better during the entire growing season.

So my conclusions at the end of the first year are;
. If you are in cold or cool climate then fertilising over winter is or may be beneficial.
. Milder climates probably not necessary.
. Warmer climates it is more important to fertilise at times other than winter.

Note that the data may be skewed because of very low numbers of trials.
Also note that a grower in medium warm area found that his JBP did better without fert in winter (but a sample of 1 is not definitive).
I would love to see some more trials from pine growers in warmer areas to help settle this question.

see more of the trial here: https://www.ausbonsai.com.au/forum/viewtopic.php?f=131&t=17981&hilit=pine,+warm&start=195

Also found some of my comparison pictures from that trial. Winter fertilised trees on the left in each pic. All had stronger, healthier growth the following year.