Hi, I'd appreciate some advice on pruning two acers (Deshojo and Ariadne) which I recently bought. Each is about 50cm high and came in a 3 litre pot and has some very long arching branches which seem to be this years growth. I intend keeping both acers in 5 litre pots long term and wonder if I can shorten (as distinct from removing) the young growth. I would like to encourage more compact growth in each cultivar. Also, the young branches on the Deshojo seems to be defoliating towards the tip. The newer leaves towards the end of the new branches appear undamaged. They have their characteristic red colour but the older leaves on the same branches appear to be shrivelling and dropping. I suspect that this comes from wind damage earlier this year when the plant was in the nursery. Is this likely? Many thanks
The defoliation you mention is pretty normal for A.p. under stress from heat/drought/wind. It seems that the spring growth of many cultivars, especially in hotter dry climates (like mine) is very suseptible to damage and defoliation when the summer heat sets in. Some time the dormant buds push new leaves in the defoliated areas and sometimes the branches are left bare and the summer growth is all that is left at the branch ends--this late summer growth is usually much more tolerant of the elements. As far as you pruning question--I usually don't hesitate to prune back branches the run unchecked, especially if you identify that you don't want a 4ft leader growing out of the side of your tree when the rest of it is only 2ft. It has been a very bad year for unilateral growth on many of my trees. I have one or two branches growing out of control on: Villa Taranto, Fireglow, Yubae, Filigree, Aka shigitasu sawa, Geisha. I obess over these one-sided growers on a daily basis and wonder why they can't spread the wealth around a bit. Much of if it is related to the fact that they are very young trees, and with age, things should settle down. Prune back what is necessary to keep a pleasing shape, but keep in mind that trees don't respond as quickly as shrubs to pruning and with maples, removal of growth in one area doesn't aways transfer it to the area you intend, nor does it guarantee overall thickening of the foliage as you are hoping for. A maple is a maple is maple and each cultivar can be encuraged to grow a certain way, but it is best to know what you have to start with and work at a compromise. Both 'Deshojo' and 'Ariadne' are trees with shrub-like tendencies meaning they probably will have a main leader, and could be multi-trunked or have multiple leaders. Initally they will likey want to grow upright and eventually spread with a more shrub-like appearance. With the container size you mention, there is no reason to prevent the upright growth of these cultivars as they will likey fill-in with age and will stay relatively small---I am starting to reach a bit here, so if you have a picture, I would be happy to give further advice-guesses:). After a couple bad pruning experiences I have taken the wait and see method. If you are unsure now, wait until spring and see what the tree does. Summer growth is very leggy and unpredictable.
Many thanks for the advice mjh. I think I will wait until spring before doing anything. Most of my acers are young and I am keeping them in pots. Generally, they have come from the nurseries planted in what looks like pure peat with some granular slow release fertiliser present and I have transferred them in their new pot to an ericacaceous compost which includes some loam and peat. This seems to kick-start some growth rather quickly. Like you, a number of my other acers have also had unbalanced spurts of growth this year, including 'Yubae', 'Katsura' and 'Villa Taranto' but nothing as 'willowy' as the growth already on the 'Ariadne' and 'Deshojo' when they arrived. JOS
