By Somhairle
Renfrewshire,
Scotland 
When and how to prune a rowan. I have a 10ft rowan in my garden. It is about 3 years old but is too tall for its trunk. Typically it was sold in the garden centre too tall and thin. It suffered badly from the strong winds in May this year and I have had it staked since then. I want to reduce the height of the tree by a third to try to balance the height with the trunk making it more stable. The top third that I plan to remove will be about 6cm thick at the main trunk.
Any tips on how to do this? Will it need sealed or should it be OK to leave the wound open.
13 Nov, 2011
Answers
It does indeed. Very clear advice, may thanks.
The tree still has loads of berries but the leaves have now all gone. But I think I will wait another month or so before doing it.
13 Nov, 2011
I'd also query what kind of stake you have in place - if its a tall straight one inserted vertically right next to the trunk, holding it rigid, that's not the best thing for getting the trunk to thicken up. The best form of staking is to drive a stake in at a 45 degree angle, then attach the tree to that, thus allowing the trunk to move or sway a bit in the breeze - this action of the wind moving it slightly encourages the plant to thicken up its trunk.
13 Nov, 2011
I actually have a pait of stakes on either side of the the trunk. It can sway slightly but was blown over in the May storms and required staking - before that I had none.
I understand what you are saying about staking but because it was blwon over, I was left with no option but to stake securely.
14 Nov, 2011
As long as it can move a bit, that should help - I also recall it being incredibly windy here in May and June, such that my new Buddleia planted last autumn now has a pronounced lean to one side. Not such a big deal as a tree sapling though...
14 Nov, 2011
I have posted an image of the tree in the original question. I am thinking of taking a third off the leader. This will also open up the tree, I think.
There are 2 or 3 strong branches slightly more than a third down from the tip. I think this may be too much to remove, however, and may go above this to some thinner branches.
14 Nov, 2011
Late autumn/winter is a good time to prune. A friend of mine is a tree surgeon and recommends it best for the tree to heal the wounds itself, and only recommends sealing if someone positively has to chop birches, ash or rowan (mountain ash) during their growing periods, which he always refuses to do!! He suggests not to cut the main trunk too low - try to cut at a shoot, so that in the spring the shoot will still pull the sap up which will stop the centre from rotting out. Then do this for all the branches to the shape and size you wish. He also advises clean cuts with either a silky saw (undercut branch first to avoid ragging) or pruners that cut without crushing, and thinning out some of the central branches to allow the wind through. Hope this helps?!
13 Nov, 2011