Backyard Forest Restoration

Rescuing Sword Fern and Bigleaf Maple

The wet season has returned – time for fall planting. **I have been rescuing Western Sword Ferns and Bigleaf Maples and moving them to spots where they have a better chance of growing to maturity. Examples of “rescue plants” include those getting crowded out by larger neighbors, growing in or too close to trails, or simply growing in spots unsuitable for their species.

I’m using the ferns to fill gaps in ground cover. Dubbed the “native workhorse of the Pacific Northwest,” Sword Fern, a.k.a Polystichum munitum, withstands a wide range of conditions and is relatively easy to transplant. Though an understory dominated by Sword Fern may seem a bit commonplace for the Puget Lowlands, it is probably our most practical option for restoring evergreen ground cover.

Mature Sword Ferns growing in favorable spots are typically about 4’ high and 4’ wide and grow dozens of new fronds every year, up to 100 according to some sources. When the old fronds lie down on the ground in spring and make way for the emerging fiddleheads, they remain attached to the base, even as they turn brown and gradually decompose. Over the years they build up a thick duff around their base that helps keep out weeds. One concern with this species is Sword Fern Die-Off, something that has plagued Seward Park in Seattle and other scattered sites in the region. One bright note in the effort to find a cause or solution is that replanting has been successful, suggesting that if a pathogen is killing the ferns, it may not persist in the soil.

Bigleaf Maples, a.k.a. Acer macrophyllum, are having their own problems in the region. We can help the species by transplanting young seedlings into spots where they have a better chance to succeed. Ideally, they need at least a few hours of direct summer sun and moist soil through the dry season. I’m planting the maples in a fairly sunny site in hopes that the maples do well enough to eventually shade out a localized infestation of Hedge Bindweed.

The sites I’ve been planting are too far from a water spigot to make hauling water easy. To compensate, I’m trying to minimize root damage by keeping generous root balls intact as I dig up the plants and move them. Sword Ferns and Bigleaf Maples are adapted to our dry seasons, and I’ve had good success with this method in the past. Nevertheless, at the height of next year’s dry season, when I’m already geared up to haul water to planting areas, I’ll do “rescue follow-up” and try to give them at least a gallon every 2-3 weeks.

**Please note that I do not advocate the rescue and transplanting of native plants anywhere other than in your own backyard forest.