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Depth to transplant sword ferns #885791

Asked September 19, 2024, 2:00 AM EDT

My neighbor wants to transplant sword ferns, and we're having discussion about the appropriate depth for the healthiest plants. I understand the root crowns should not be buried, and she seems to be a fan of a thick coat of dirt or mulch. An impartial opinion would be appreciated, especially since she respects the folks at OSU. Thanks!

Clackamas County Oregon

Expert Response

Thank you for your question, Laurie.  Here is a brief description of this native species:  

Sword Fern, Polystichum munitum

Evergreen fern. Ht. 2’-3’. Part sun/full shade. Provides winter protection for birds.

Notes: Transplants well, easy to establish. Looks best planted in groups or drifts in the woodland or rhodie garden. Spores spread around the garden for new plants. Our only fern, which can handle more sun/more dryness than all others. With age, can reach heights of 5’. Leaf looks like a sword, hence the name.   https://extension.oregonstate.edu/gardening/techniques/pacific-nw-native-plants-plant-community

It is recommended that this species be planted in loamy, loose soil that gets adequate moisture during the year, but does not get buried in wet clay during the winter.  Although the crowns should be left just at the top of the soil, the roots need to be buried so the plant can spread out.  In order to protect the crown from snow and ice, mulch such as bark chips (not small and matted) or shredded leaves.  If the mulch "sticks together", it prevents moisture from penetrating the top soil and reaching the roots.  I hope this is helpful.  Good luck!

An Ask Extension Expert Replied September 19, 2024, 6:02 PM EDT

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