We have a stella magnolia shrub that we planted 2 years ago (lots of sun, sandy soil). It is thriving and is now about 2.5 feet tall and 3.5 feet wide. We do not want it to get any bigger as we are afraid of root spread destabilizing the garden wall behind it and to the side where there are stone stairs. If we continue to prune the shrub so that it remains this size (or a bit smaller), will that keep the roots from spreading as well? Or is there concern, and should we just dig it up.
Thank you for contacting the Toronto Master Gardeners.
Magnolia stellata is a slow growing deciduous plant which can be grown as a large shrub or pruned up as a small multistemmed tree. It eventually reaches a height of 15-20 feet with a rounded crown spreading to 10-15 feet when mature and a root spread of 10-15ft.
This tree/shrub does best when planted in moist, organic acid soil in full sun (6hrs). If possible this shrub should be planted in a protected area to prevent buds from opening early and then being killed by a late frost or freeze. This shrub generally does not need any pruning – unless you wish to train it to a tree shape. Pruning should be done after flowering to avoid cutting off buds set for the next season.
When selecting a spot for any plant you should always to plant according to “right plant, right place” instead of trying to conform the plant to a specific area. This just leads to an underperforming plant plus more maintenance on your part.
My suggestion if you are worried about root spread is to dig up the shrub and move it to a more desiriable location so that this spectacular specimen can reach it’s full potential.
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