Answer: Mugo pines can not be trimmed the way one might trim a deciduous shrub. You can, however, slow the expansion by breaking off a portion of the growing tips or "candles" in the springtime when they begin to swell or expand. The new growth only occurs annually and only at the tips of the branches, so breaking off part of that spring growth will limit the growth for the entire year. It will also cause the plant to branch and grow denser each time you do this.
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