Very acid soil, mostly shady

9 years ago

I want ground cover we can walk on but don't need to mow. The soil is very acid (mainly decomposed pine needles) and mostly shaded. If possible, I would like to identify and transplant plants already growing on the property, both because they are proven to tolerate the conditions and because I'm cheap. But I'll buy plant where necessary.
The plant that seems to do best in several parts of our property is lily of the valley. The ones in the photo, I did a rather brutal job of ripping out of the lawn late last fall, leaving most of the soil behind, then planted big chunks of the roots in a problem slope that has killed all the purchased plants my wife has had professionals plant over the years. Each of these chunks of roots sprouted into bunches like this, earlier than the same plant left undisturbed elsewhere.
Meanwhile, slightly earlier last fall I took giant slabs of soil with lily roots from parts of the "lawn" where the lily had not just invaded. It had taken over 100%. I put those in a different area where I need something with strong roots that will stand up to a lot of physical abuse, super acid (like the whole property) and 60% sun (same sun % as the ones in the photo). Those are barely starting, well behind the established lily, which is well behind the ones in this photo. That "physical abuse" hasn't started yet. I don't know why those are doing so badly. All parts of the property got plenty of rain recently. Does it do better after a rough transplant?? Or what other factor makes the difference? The ones doing very well went into a steep slope. The transplanted slabs doing badly went into a less steep slope. Most of the places it invaded on its own are even less steep (nothing here is level). All of it is places with 40% to 70% sun.
If the lily fails, what plant should I try? I have a 45 degree slope covered with big rocks (which I want to leave that way) and above that a gentle slope where I put those giant slabs of lily, and above that a gentle slope with bark mulch covered by an inch of pine needles with a few new bushes planted last fall. I don't know if runoff from the bark mulch and pine needles is a factor. At 60%, this is the sunniest area for which I want ground cover. I transplanted moss (from the front lawn!) into the shadiest areas. Still don't know if that will take. I plan to transplant wild violet from the front lawn into other areas. The wild violet is growing in the one place on the property that has full sun. But online info implies it will do well in less sunny spots.

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Comments (4)

jsf67
Original Author
9 years ago
I tried and failed to get the ruler to show in this photo. This is part of one of the big slabs I transplanted last fall going deep enough to not cut the roots. It is doing so much worse the the above brutal transplant. These tallest of these shoots are 10cm. The plants in the first photo are 20cm.

Does the appearance or size info give a clue of what I did wrong?
gardengal48 (PNW Z8/9)
9 years ago
How do you know your soil is very acid? Have you had it tested? Pine/conifer needles do not make soil acidic - that is entirely due to the underlying mineral content and the amount of rainfall. Regardless, most plants prefer acidic soil as long as it is not overly acidic - anywhere from about 5.5 to 6.5 is fine for the vast majority of plants.

Lily of the valley do not tolerate foot traffic. In fact, really only the flattest growing, matt-like groundcovers will tolerate much foot traffic. These are things like creeping thyme, Scotch or Irish moss, rupturewort, blue star creeper, etc. Plants that get much taller or that have more succulent foliage - like ajuga or lamium - can take some foot traffic but not much. I'd consider something like creeping or wood phlox, depending exactly on the amount of shade you may have.
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jsf67
Original Author
9 years ago
I guess I was misinformed about pine needles. I tested the soil a few times when the lawn started dying and getting replaced by moss soon, after I moved in many years ago. I don't recall numbers, just that I was told it was too acid for a lawn. A month after I put down a large amount of lime, it was nearly the right pH for lawn. A month after that, it was back to the original. Repeated applications of lime after that, weren't controlling it. So I decided to just see what would grow without using lime. About 50% of the "lawn" is currently grass and about 20% moss, plus a mix of other things.

We have lily of the valley in several places now and it seem to tolerate foot traffic well. It looks too tall and fragile for foot traffic, and we were initially careful of it in the garden section where we wanted it. But in the parts of the lawn where we don't want it and haven't yet had time to pull it out, we are certainly not careful and it doesn't care. So we have been walking on it in even the parts of the garden where we do want it.

The transplants in that second photo are at least still growing. I don't know why those are doing worse than lily of the valley elsewhere on the property. But if it is just slower, not ultimately weaker than the rest, I guess it doesn't matter. (We don't need to walk on those yet. Only after other planned plantings are put near there next year.)
gardengal48 (PNW Z8/9)
9 years ago
Most turf grasses actually prefer an acidic soil and moss grows for all sorts of reasons, not just because soil is very acidic (moss can grow in neutral or even alkaline soils as well). Based on my experience, I'd guess the reason the lawn grasses are not thriving is because of the pines or other large conifers provide too much shade as well as rob the soil of moisture and nutrients necessary for the lawn to do well.

If you are happy with how the LOV holds up to being walked on, great. It grows very densely in my garden, so it would be very noticeable by the crushed foliage pathway if one walked across it. Or you can experiment with some of the other suggestions and pick what you prefer.