Hello everyone. I have some mahaleb cherry and crabapple seedlings and want to give their trunks a dramatic shape while they are still flexible. What is the best season to do it: in spring or early fall? I live in a fairly cold climate, the temperature in greenhouse can drop to -5C. Strong bends create micro wounds, will the tree have time to heal them before December, if it’s done in September? I’m also considering doing it in the spring, but this is a period of strong sap flow, maybe it will be difficult to do it on mahaleb cherries and crabapples, or I’m wrong?
Where I live, Piedmont area of North Carolina there is plenty of time for bending and recovery before the cold gets here. You don’t state where you are. When is your first frost? You have a greenhouse so you can extend that time by keeping tree in it. And just because a tree looses leaves doesn’t mean that the rest of the plant isn’t active. A wound won’t be ignored by the trees defensive system even without leaves on the tree. I’d go ahead and make the bends. Just keep an eye on the wiring come spring when growth really takes off, you don’t want a rapid expansion of trunk and limb diameter to make the wire cut into the bark.
Stable night frost usually occur in November, at least -5C. Daytime temperatures range from 0+5C. Really frosty weather only comes in December. But there are always exceptions, the weather is unpredictable.
The nice thing about wiring in spring (May/June) is that the bends set faster and you don’t need to protect the tree over winter. When temps drop below freezing, it’s easier for wired branches to die off in winter.
Early spring, right before the trees leaf out is another good time to wire. When you wire in fall and how big the bends are will determine the need for protection in winter.