Prunella vulgaris (Common Self Heal) With Hostas and Ferns

Asked August 26, 2019, 10:34 PM EDT

We have a small grove (approx. 1,600 square feet) of Western Red Cedars that we recently removed all of the ground covering ivy, poison oak, blackberries and nettles from. The area also has several sword ferns and hostas.

The Prunella REALLY wants to take over the open ground. I am fine with that, and containing it at the boundaries. My question is whether it will work well with the ferns and hostas or will it choke them out. As the ferns and hostas are in the 2-2.5 foot tall range, if the Prunella stays closer to 1 foot tall, it may give us the sort of natural soft, shady look we are hoping for... If they will play well together.

Also, how well will the Prunella do at blocking errant dandylions, grass and the other stuff we cleared out?

Thanks in advance!

Clackamas County Oregon

3 Responses

Native plants don't always "play well together", but how yours will do is an experiment I don't have scientific recommendations for. Research is lacking, so experience and judgement are the best I can offer.
The self-heal might smother the crown of the Hosta when it is dormant. It also provides cover for snails/slugs. A boundary of bare mulch there might reduce slug damage. As the cedars grow, Hostas may fail due to lack of water.
Lack of water might also limit the groundcover in coming years or leave it looking unattractive in the late summer. What works one year might not in the future as root competition changes. I expect the fern to do okay with short groundcovers.
The perennial weeds (Dandelion, ivy, grass) are likely to have strong root systems and will regularly reappear. Persistent removal is required to keep weeds at bay. There is not an herbicide which will inhibit some broadleaf plants but not others, making manual removal an option.
Wood chips as a mulch are something to consider under your conifers if the groundcover doesn't work. Mulch aids with holding soil moisture and reduces weeds seeding in. Here's an article from Washington State Extension
Something you didn't ask, but has been in the news so I'll bring it to your attention, is the drought damaging our conifers. A quote from the article "People don’t think about watering big trees, he noted, but that’s the best method to prevent death or possibly bring a not-too-stressed tree back to health. One option is to consider watering at least six hours every two to four weeks August through September. Using a soaker hose wound around the tree out to the drip line (how far the branches reach) is much more efficient than other methods. Though the cost of water adds up, Shaw said, it’s cheaper than removing a large tree, which can cost thousands of dollars."

Thank you for the reply, Jacki.

The idea of mulching around the Hostas is to provide a space buffer is good. Perhaps also for making access paths through the grove.

Fortunately, we are on our own high volume well, and have a good water table, so we actively water everything through the summer months. It helps keep things green, helps with fire hazard reduction, and ultimately, goes right back into our the same ground water source we draw it from. We use wide area impact sprinklers for several hours each week.

We had intended to use Vinca to replace the ivy ground layer that the previous owner had allowed to run rampant, including climbing into the Cedars. We have removed all of it on the ground, and most of what was climbing the trees, but it's an ongoing challenge. So too are the poison oak, blackberries and nettles, which we work are by hand and with spot spraying.

There is a lot of bare soil that needs to be covered, and the Prunella seems to be overtaking the Vinca 2-to-1, even though we have not planted any Prunella. So, I'm starting to think we should go with what seems to be winning the race.

Any other thoughts are welcome!

Vinca isn't a favorite, as it has spread beyond our yards. I have not heard of any plant that can out-compete established ivy, which is why it is such a tough invader to deal with. Seems you have the right idea of vigilance and that's all anyone can do.