Ground Cover for horrendous site

Camano Island, WA(Zone 8a)

Hi everybody,

I have a sunny 45 degree slope that has 2 5 ft. high layers and runs more than 100 feet. I need to stabilize it with a ground cover. The bottom slope's "soil" is actually hardpan clay with rocks. The top slope's soil is regular old clay with rocks. Digging in it is really tough. It'd be nice to have something growing before the winter rains start (we have dry summers and wet winters).

I was thinking of ways to stabilize the slope:
1. painfully plant lots (hundreds) of ground cover starts like Cotoneaster
2. put lots and lots of seeds (not sure what kind) on the slope and water verrry carefully
3. tack burlap on the slope and plant ground cover starts in holes that I cut in the burlap
4. tack burlap on the slope and somehow embed groundcover seeds in the burlap
5. ???

Anybody have experience with such a challenge? Anybody know of a fast-growing, zone 8 evergreen groundcover that tolerates getting no watering once it is established? Invasive is probably ok because the soil is so bad that nothing can invade, except I draw the line at planting ivy. :-)

Thanks for your suggestions!

Thumbnail by momlady Thumbnail by momlady Thumbnail by momlady
(Zone 5a)

I've been dealing with a slope here, trying to find things that will hold, but my growing conditions are much different. I am battling creeping charlie (ground ivy) that has covered the entire thing and am looking into aggressive natives that can overwhelm the area. My line is no White Sage!! :) I haven't tried seed yet, but the plants with even shallow roots have held when we have flooding rains and I used no burlap.

I hope someone here will give you some good advice based on personal experience, but I did a quick search and found a list of Washington native, evergreen ground covers. Plants native to your area may grow better. Sometimes they can be slow to establish before filling in, other times they can explode! (That White Sage I have in another area)
http://www.wnps.org/landscaping/herbarium/evergreengroundcoverlist.html
http://www.wnps.org/landscaping/herbarium/index.html

You mention ground cover... how high are you willing to go? If a little taller, than your options would increase. I prefer no higher than a foot, but will go up to three in my battle with creeping charlie!

I hope you find some good plants to fill in the area. It looks like it would be a nice refreshing place when it is covered in green.

Camano Island, WA(Zone 8a)

Chillybean, it's always interesting to see how regional the invasives are. I look at pictures of plants in other areas that I could NEVER use here, and vice versa. I don't know White Sage - it sounds like I'm lucky that I don't!! Now creeping charlie I do know. That is one tenacious weed!

I am encouraged by your news about plants succeeding on your slope. That's great, thanks for sharing!

I am not sure how high to go on the ground cover. I'd been thinking about a foot, also.

Thanks for the leads on the native plants. It makes lots of sense to go with a plant that is happy in this climate...but not too happy, like an invasive exotic would be.

Thanks for the help!!

Lake Stevens, WA(Zone 8a)

That is a nice list, thanks for finding it. However, except for kinnikinnick I doubt any have a chance.

Arctostaphylos uva-ursi (Kinnikinnick, Bearberry) Works great here for me, in full sun and clay, but momlady found her local nursery says gets a crisped there (less rain).
Linnaea borealis (Twinflower) I tried it a few times, died out. Shady habitat.
Mahonia nervosa (Dull Oregon Grape) gets 2-3 feet tall, another woodlander.
Penstemon davidsonii (Davidson's Penstemon). I tried it died, like all penstemons here (clay?)
Sedum spathulifolium (Broad-leaved Stonecrop) survives here, dislikes the clay, OK on edges only.

Baltimore, MD(Zone 7b)

It's rather invasive here, but vinca minor is tough and fast spreading.

(Zone 5a)

Quote from Pistil :

Penstemon davidsonii (Davidson's Penstemon). I tried it died, like all penstemons here (clay?)


Might not have been the clay. I have two native Penstemons thriving in clay subsoil, Large-flowered and Purple Ozark. They are not on a steep slope, though, maybe 20-30 degree maximum, if my estimator is working. :)

(Zone 5a)

Quote from momlady :
I don't know White Sage - it sounds like I'm lucky that I don't!! Now creeping charlie I do know. That is one tenacious weed!

I am encouraged by your news about plants succeeding on your slope. That's great, thanks for sharing!


White Sage is a prairie plant and our poor soil is just right for it, according to one site. I doubt I'd have much problem with it if it was "out there" rather than in the middle of some of my rare plants. Oh, I wish I knew its growth habit before planting it. I peaked and it is native to most of your state. When it is in a nice colony by itself, it can look attractive.

We had another flooding rain yesterday. I verified with my husband that our slope is about 45 degrees, but near the driveway it is steeper. I've started Monarda fistulosa (Bee Balm) that I intend to plant there since it reseeds easily. It's a bit taller than I'd like for the spot (3 feet), but I really like their form in the spring before they flop a little. (I posted a picture.) It grows in a wide variety of conditions here, one of them being full sun and clay, rocky soil. It is native to a portion of your state. It's not the evergreen you are hoping for, though. It dies back in the fall.

Tenacious... yep, that describes creeping charlie. We avoid use of herbicides, but it sure is tempting in this case.

Thumbnail by Chillybean
Lake Stevens, WA(Zone 8a)

oops I forgot about Penstemon pinifolius, that one has survived, on a little heap of purchased "soil". I like it a lot, blooms a long time.

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