Hi, I'm new to this board, so hope you can help. I've been asked to transplant a 2-3 year old M.x Soulangeana which at present is in a narrow gap between a tall hedge and a concrete path. This means the branches are all growing on one side, over the path, so the roots will be under the path! As I can't dig up the path, I need to prune the roots - should I cut back the branches to correspond? I'll wait until after leaf-fall, and dig the planting hole first. The new area is grassed, soil is heavy and clayey, with clay subsoil, prone to waterlogging. Should I break up the subsoil? I've heard that fibrous matter shouldn't be dug in as it prevents the soil from settling properly and the tree could fail. Does it need feeding? And how much bare soil should I leave around the base? Also I've been told to replant it facing the same direction - so it will be facing towards other hedges, away from view - they are several feet away though. Will the currently bare side of the tree eventually grow branches, as that will then be facing the light? I'm in the south of the UK...
It's a bit of a horticultural myth that the roots only grow where the branches grow. The root density will be highest in the soil with ideal conditions for that plant....so for Magnolia, consistently moist, well aerated, non-compacted soil. The root density for your Magnolia will be highest in the area parallel to the path & the hedge despite where the branches grow. As for the clay, it's not been a problem for Magnolias in our area. What do you mean by waterlogging though. Are you refering to surface flooding or a shallow water table? Saucer magnolia does not like wet feet (it likes moist ones). If the waterlogging is occasional, probably not an issue...if it's frequent, the tree will suffer. In short, yes, the tree will become more symetrical over time but only from the live buds on the young branches. Sprouts are not going to burst from the trunk of the tree in response to the light. Saucer magnolias are not small trees when mature (20' tall x 30' wide). If you have a space issue after 2-3 years in the ground, you've planted it in the wrong spot...make sure the new spot offers better spacing for it. Simon
Cutting back the top actually makes the plant less able to respond to cutting of roots. Since this tree is a subject that often does not do well with much root reduction, you may not actually be able to move this particular specimen if you have to cut off half the roots on one side, close to the stem(s) to get it out. Although some saucer magnolias are field grown and sold balled in burlap, like other magnolias many are grown in containers instead. Probably this is at least partly because of the failures that may occur with cutting of their roots.
Many thanks for your replies and advice! The owners have now said moving it to the only available space would interfere with lawn mowing, so I am now relieved of that problem! However, one book suggests it can be grown as a single-stemmed shrub - the branches at present scratch the car as it's parked there, which is also why they wanted it moved. How would it respond to having its lower branches removed? As I'm their gardener (they mow the lawn...) I need to ensure success, though I told them it may not work...
As you can see from the attached photo, growing M. x soulangeana as a single stem tree is not an issue. I don't think your clients have a clue how big they can get? Simon
If you were starting out with a small one or the one there is still small it could be trained into a single-stem tree, but once the main framework has been long established it is too late. If you can clear the stem of the specimen in question by cutting off some quite small branches only then that is still possible.
That sounds hopeful, Ron. It's still only about 7 ft high, with the stem about 2 ins thick max., so maybe it can be done? The book wasn't very specific - how would you go about it please?
I'd have to look at it. A general approach is to nibble back side branches below desired crown height for some years, then cut these off completely when the crown above them is well along. If you prevent low branches from elongating eventually these begin to be shaded out by those above them, because these latter are allowed to elongate unrestricted. Prune in midsummer. Since saucer magnolias are generally bushy a comparatively low, wide head is probably the best to hope for. If the plant is small enough to move that might still be best. Some saucer magnolias grow very broad crowns unless crowded.
