I have to say that was an interesting read. I'm not sure that I agree that grass isn't an erosion deterent, I have no proof but it seems to be holding my hill okay. But his comments about having multiple layers of foliage does make sense.

Thanks Cherry for posting this!

I think mono culture is a problem.
If a hill is planted only with grass and nothing else it may not hold over the long term.
I also think that the "site" thinks natives are the best solution to erosion control.
I recently introduced ornamental grass my hillside, that is used for erosion control.
Cherry

Las Pilitas is a native plant nursery, so of course they think natives are the best solution. And their site has no much information for us Californians but they come off as a little arrogant sometimes. I think there's less science and more educated guessing in this area than the "experts" like to let on.

I avoid monoculture on my slope mostly because there are so many differing opinions about what's best to plant, and they change so often, that I figure planting a lot of different things is the best plan. Not too long ago Californians were told to put ice plant on their slopes, and now everyone's tearing it out because it's so shallow-rooted that it's apparently the worst thing ever to plant on a slope. And I think Las Pilitas is too quick to dismiss grasses. I read recently that there are some fescue varieties that send roots as much as twenty feet down. Surely they would be good choices for erosion control!

And I also try to plant things that grow naturally on hillsides, figuring that they're adapted both to the drainage conditions, the dryness, and the slope. I mean, there are a lot of California native plants that grow near rivers or on flats or in the desert that I think would probably be less helpful to holding my hillside than exotics that grow on hills in Australia or China.

I don't want to diminish the importance of erosion control but I honestly think people panic when they hear the word "erosion". I think it's important to be sure the hill is stabilized but no matter what you do some erosion is going to happen, it's just a fact of nature.

But I also don't live in an area that is prone to mudslides. And I will admit to occassionally getting panicky that my house is going to fall off the hill!

Yep, I live in an area with rocky clay soil and erosion is just surface erosion, not structural stability. I looked around very carefully before deciding what to plant and realized that on the mountiansides here, entire mature hardwood forests flourish. So there are quite a lot of things you can plant on a hill if you're careful.

We are mostly going with native shrubs because they are virtually maintenance free. We are also using a lot of native ornamental grasses---- Little Bluestem and Switchgrass. Both have massive root systems and are recommended for erosion control, and since they only need to be cut back once a year they are also very low maintenance. However the Little Bluestem seems to fall over when the seedheads get too long.

We mixed in some black-eyed susans (rudbeckia) and purple coneflower, which are also low-maintenance and native. And our newest additions are two Grey Owl junipers. I think a mix of plants looks better and also provides better stability in the long run.

Big rocks are also nice and very low mainitenance. LOL

I suspect the steepness of the slope and the uses to which the slope are put are important to whether grass will work.
I have used native red fescue with some success on a very steep slope and it mitigates erosion from rain but it can't take anyone walking (climbing really) on it. Might have to go with something with bigger roots or bite the bullet and put in terraces or big rocks or whatever if it is ever going to be a walkable slope.