I still have a red maple seedling that hasn't dropped all of its leaves(!)
Cold hardy deciduous trees trees are built to have a cold season dormancy and do best meeting their ideal number of chilling hours. I've seen Japanese maple trees break dormancy as early as December- unlikely to have met their typical chilling requirements- and grew well enough. I would bet that one shortened dormancy wouldn't weaken a tree excessively, but the shorter the dormancy/fewer chilling hours acquired, the weaker the tree will grow the following season, not to mention that the conditions for growth, specifically sun intensity and ambient temps- are at their lowest of the year for the next few months. Missing chilling requirements- year over year will likely weaken trees further. That's how I understand it.
I experienced that when I first moved here to central Florida. My Japanese maples would only get maybe 200-300 chill hours. They struggle along for a couple of years then die. I still grow them here but I do it be forcing them into dormancy and put them into a fridge for three months. Take them out early March and they grow like crazy. Gotta give them what they need.
That's more dedication than I can muster at this point. I applaud your efforts.
Actually it comes out to less effort than having to worry about them from Dec thru March. Only took me three hours to defoliate everything and load up the fridge. All I have to do is make sure they don’t dry out in the fridge. Having said that though there is the added expense of having a dedicated fridge just for maples and cherry blossom trees. If all the ones I have now keep growing well, a second fridge will be needed. But, When I look at how much I was spending on a 200 gallon saltwater reef tank that was loaded with SPS corals, another fridge just doesn’t seem that much to me.
I just checked the soil temps in my pots in the greenhouse and they are in the low to mid 40s. So they are about what the average air temp has been in there since December (46 F). This is pretty much what I expected based on other folks experiences with cold greenhouses. I have my heater set to come on at 34 and off at 36, but the average is pulled upwards by the daytime highs.
Same here with Japanese maple seedlings and air layers, plus a couple of crab apples.
I’m sure my power bill wishes I hadn’t had to use my greenhouse heater
I wouldn’t call our weather here weird, but to does pose problems for some of the indigenous plants. We stay fairly warm (50F - 80F) through the winter months and just have dips down into the low 30s or maybe high 20s. A lot of things here will get frost bite because they break dormancy too early. It was in the low 80s last week and we might hit 28F come Thursday. I just know it’s going to happen and watch the plants in pots that break early and bring them inside as the cold front moves through. They usually only last a few days and we are back in the 70s or 80s. And yes, all my high chill time trees go in the fridge for three months.
