Answer: Hypericum can be propagated by tip cuttings from June through October. Dip the cut ends in rooting hormone then place in moistened potting soil. They usually root in a few short weeks. I don't think your established St. John's Wort will die if you cut it back. If anything, it will respond with lush new growth. But, just to be on the safe side, you can take cuttings before you prune the plants back.
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