Trident and Japanese Red Maple Wintering question

Surrey John

With you, Stymie. During the past 10 days I've repotted an Ulmus parviflora, a Pseudolarix, a Larix deciduosa, a Taxus baccata, a Quercus, a Corylus, a Lonicera, and three Cotoneasters. I think I got the larches just in time - swelling buds are just breaking into their first green. No lagging, nothing for any of them - they are all in exactly the same situation as all the other plants overwintering in my garden. That said, I have to admit that I can't remember ever experiencing temperatures more than 4-5C in this low lying Thames valley region. SJ

emorrin

John,

I always thought that the root ball had to get above 10C for a few days in order for dormancy to break. I am surprised that with 2-3C that this is happening.

I decided and I am going to re pot this week. I am just waiting for my baked akadama to come in. I just hope that the root pruning I plan on doing (cutting off the high exposed roots that don't belong, won't shock it too much. I understand that the Trident maple is a resilient tree though.

Thanks to everyone who as replied this far. I will post a picture of it this spring once it has fully leafed out.

yamadorinige

Your certainly right in saying trident maples are resilient, I repot mine every year and the pot is always packed with roots. I usually remove upto one half of the roots but it just on keeps growing more Very Happy

Surrey John

Ed, I've not heard that before about a 10 threshold for dormancy to break. I think, from what I remember of my botany, that it is definitely temperature which is the controlling factor, but I suspect that it must be an average over time which is the determinant, and I should be surprised if the average needed to be as high as 10 in a temperate zone. Have you a source for this information? I should be interested to consult it.

Good luck. SJ

emorrin

SJ,

Here is a link below that has some info on dormancy. I was a little off though in my conversion from Fahrenheit to Celsius. The magic temperature seems to be 40 degrees Fahrenheit which is 4.4 C not 10C. That would better explain why your bonsai are starting to bud. Since I am from the U.S. and always used Fahrenheit, I can never seem to get a good grasp of Celsius. 10 C is another magic number for something else but for the likes of me I cannot remember at the moment.

I have read about this in one or more of my bonsai books as well. I believe "The complete book of Bonsai" by Harry Tomlinson mentions this. I also remember this from a horticulture class I took in college. The temperature of the root ball is the main triggering factor for breaking dormancy. Once the root ball reaches 40F or 4.4C for a week or more than dormancy usually breaks. Light is also a small factor but more of a factor for starting dormancy as the shorter days trigger it. Photosynthesis doesn't occur below 36F or 2.2C for evergreen trees. Of course this is not a factor for dedicious trees as they have no leafs at this time.

http://www.evergreengardenworks.com/dormancy.htm

emorrin

Nige,

I was a little surprised myself that even though the tree is in proper bonsai soil, I was easily able to take it out of the pot due to the roots being so dense. It is definitely root bound. I thought that maybe the person who I bought this from wasn't telling the whole truth when he said it was re potted last spring. Apparently he was.

I am going to have one major job this week when I re pot.

TB420

Ed, I would hope very much that your tree does not leaf out very soon. Last year we had a very warm late winter then a long late cold snap. Many people lost tree's or had them seriously damaged. I put all my tree's that were in leaf in my greenhouse, but not everyone has that luxury.

SJ and Nige. I don't know where in Illinois Ed lives but I live one state over same zone and we just got about 3" of snow then sleet/ice a couple days ago, right now it is sleeting with accumulating snow forecast. In the 5 day forecast we have snow forecast for 4 of them low temps 8f (-13c) and below freezing until Friday, then Saturday is 40F (4c) high and 25f (-4c). Around here the saying is March is in like a lion and out like a lamb, then April showers bring may flowers.

Ed it seems as though you sheltered it to much. I put my tree's up a couple times for several day each. We only had a couple cold stretches that worried me. All my hardy tree's have been outside almost all winter and they are all still dormant and alive. Maybe plan for a cold frame or a polyhouse next year.

Tom

Surrey John

Hey Tom, and Ed, thanks for all your info re low temps. Living where I do (Thames Valley, just SW of london), I hardly ever experience "severe" winters, and when "severe", they never go down as far as 10 Celsius. I can't remember, for example, when was the last time we had snow which settled for more than 24 hours - and I can't remember any snow, ever, which was more than 12" deep. Even the "great freeze-ups" of 1947 aand 1963 were nothing compared with what you regularly face. I's a bit different I think further north in the UK where Stymie lives - high on a hill in Sheffield - but even there I don't think conditions get anywhere near the conditions that can hit you. That's partly the effect of being right next to London - large connurbations are always slightly warmer - but also of course being in the SE of England and on the gulf stream. So I am very grateful that I don't ever have to cope with the kind of regular winter cold guys like you have to face.

Still - what happens to te trees growing naturally