The Q&A Archives: When do I prune St. Johnswort "Hypericum androsaemum"

Question: Last Summer I planted 3 St. Johnswort plants and they did extremely well with lots of fruit and flowers. I had been told that they would be evergreen through the winter. The plants turned totally brown and now appear to not be coming back at all for spring. I have not yet cut them back because I am not sure how far back to cut them. Or, Are they dead??

I sent this same question about 10 days ago and received an e-mail that I would have an answer in a couple of days. I have yet to hear. Please respond!

Answer: In a quick search I did not find any descriptions of this plant indicating it should be evergreen. (Perhaps in a very mild winter climate it might be semievergreen but it is described as deciduous.) Generally speaking in spring you would trim it back to live wood, removing any winter damaged stems. Start at the tips and work your way down the plant. Dead wood will be dull, brittle, and snap in your fingers. Live wood will be somewhat supple and will have green inside the bark. In a severe winter it kill back as far as the roots, however with luck it should recover and be fine once the growing season takes hold. I might point out that your zip code places you toward the coldest part of its hardiness range, so I hope yours was well mulched and is in a spot with some winter wind protection for best results. ps I remember answering your question a while back, I'm sorry you did not receive the answer I sent you. Perhaps there was a typo in your email address or it is caught up in a spam filter or something like that happened.

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