I also wanted to add that I have many Ponderosa Pines that shed needles every year. I often use these to mulch, so maintaining a graveled area could be difficult with raking the needles.

And, I know it is looking a bit shabby, but I just did the first mow of the year, and my lawn mower needed a part replaced, so I spent most of my yard time doing that.

Few people want to incur the expense of retaining wall and regrading if a slope can work. Here, the problem is just surface maintenance.

Mulch alone, as it isn't pretty green, needs occasional replenishment and sometimes slides down the hill, is rarely a satisfactory solution. Groundcover solves all of these problems and, IMO, is the best solution. What's more, it "eats" fallen leaves (they sift down into the groundcover) so there is no leaf litter clean-up within the groundcover area. Pine needles have a tendency to lay on top of some groundcovers, but they can be lightly raked or blown off the top, or helped along in the settling process. It looks like there is some groundcover further back in the picture. Why couldn't that same plant be used as groundcover on the slope? Already having it as a source might make creating more easy and relatively inexpensive.

Gravel would be a chore to install, and to create an edge that divides it from the lawn. Likely, it would migrate downhill on an unrelenting basis. Worse, it would be a huge pain to remove.

I too would go with a groundcover. You say it's very dry. If it's mostly shady, Geranium macrorrhizum (Big Root Geranium) should do well. It's semi evergreen, deer resistant, blooms in late spring, needs virtually no care, is easy to keep under control, and will fill in fairly rapidly. I'd start with the steepest section. Kill off the grass with roundup and plant right in the dead grass. You could then mulch between the little starts.

I lived in an area of row houses where most folks had tiny, hilly front yards. About 50% of the folks covered the front yard with ground covers. Mine was half and half and the only reason I didn't go 100% is that it takes a while to get established. Which is why you may need to mulch a bit at first or do it in stages, like Lacy says, starting with the steepest areas. You can use logs or boards to temporarily keep the mulch in place, but as it decays the groundcover should be well established. But after 2-3 years all you'll ever have to do is weed it a couple times a season. Plus it will look way prettier and more interesting than grass!

Thanks all! It's actually a super sunny spot. I do have some wild geranium and sedum in the garden and love the look. I'd like to put some phlox down the side where the rocks are to get started.

You might take a walk around your neighbourhood and see if you can find some friendly folks who may have other groundcover plants to share. Gravel is a pain with upkeep -- even with landscape fabric you will get a lot of surface weeds and it can start to look very messy very quickly.

Can I Plant the ground cover on top of the grass?

That's so awesome! Thanks!

You cannot plant groundcover in grass without killing the grass first. If you did, it would be the weediest, ugliest, impossible-to-maintain mess you ever saw.

If the swale is a drainage path, you would not want to be blocking it with any boulders. Isn't part of the slope in question connected to the background of the picture?

So it's sunny. Try Geranium 'Biokovo' or 'Karmina'. Or use groundcover junipers; my favorite is Japanese Garden junipers, though they get very wide and eventually you'll have to learn how to prune them properly to keep them in bounds. Not hard, but there's a right way and then many wrong ways.

You can use old cardboard boxes, opened up and laid down heavily to kill the grass, then put mulch on top of it. The cardboard will decompose eventually and you'll be able to plant through it. I have grown Biokovo and it is absolutely gorgeous. It was last year's "Perennial of the Year" selection by the American Perennial Plant Association, and we sold out of it at our plant sale. You could even eventually have a cool rock garden there if you wanted, but if you're not a big gardener type, I imagine you just want to get a groundcover established there asap. There are a lot of options. If you google "groundcover lawn replacement" or "planting groundcover area" you can find lots of photos and also videos with instructions. Here's a good example, from "This Old House." He suggests removing the grass by hand (digging it out) which you could also do, but with that large of an area, I dunno. It's cheaper than gym membership! http://www.thisoldhouse.com/toh/video/0,,20052304,00.html  

Note: I wouldn't use ivy like is in the video, since you will be forever trying to keep it from growing up your pine trees. Creeping phlox was another popular groundcover choice in my neighborhood. I used "Uva ursi" in my yard. Uva ursi goes by the popular names "bearberry" and "kinnikinnick." There are also many colorful sedums that folks use as groundcovers.

Not to divert the thread, but I am considering using bearberry as a groundcover. pinkmountain, could you say some more about your experience with it? Where do you have it planted (zone and yard location)? Does it do well, spread rapidly, and suppress weeds? Thanks!

I actually have experience with cardboard and beds. It worked beautifully and my soil is so rich. I literally just covered the flat area and mulched. The following year my family helped me put in a developing flower bed. I'd like to do this eventually in the slope with some evergreens and ground cover.

I was in zone 5 B. It worked great as a groundcover. It needs SUN. I had it under a tree and it was forever creeping away, trying to find sun. It looked leggy in my situation, so don't use it unless you can give it the sun it needs. Some folks have told me that it has a reputation for not growing well, but that was not my experience. I got mine from a native plant nursery and it grew very well, exceeding my expectations. Evidently there are new breeds out there that do very well as a ground cover. I am seeing it more and more in common and ubiquitous places where they sell plants. Worth seeking out if you can't find it, it is so lovely! Get good plant stock with good genes from a reputable source. I love it because it is native and much better behaved than something like ivy, ugh!

Here's a picture of it growing under a tree in my last yard. Don't go by this picture as a good example of how it will work in a sunny yard. As you can see, it is climbing away from the bed in search of the sun on the path and other side of the yard. It's way more leggy there than it would look in a typical yard in the sun. The stuff to the far left is sweet woodruff, which is one thing I would recommend in a shade situation, although there are many, many other options. I grew sweet woodruff because if it's herbal qualities and white flowers in spring. It is used to flavor "May wine."

Gorgeous with the hosta!

Thank you! The information is very helpful and your garden looks great!

As someone dealing with the same kind of conversion of slopes, may I just second the suggestion above to plant some trees to create some shade - even dappled shade? The difference in maintaining a shady slope vs a sunny one is night and day. The weeds are slower. The watering is less or non-existent.

While I love the strategy of cardboard with thick mulch on top to kill off grass, IME doing this on a slope is tough since the cardboard is smooth and the mulch slides. If you are going to do this, research to find the most irregular, jaggedy, fringy mulch you can so that it will knit together. Use heavy boards or rocks or bricks placed periodically to help hold the mulch and cardboard in place. Or alternatively, use Lacyvail's glyphosate (generic Roundup) strategy or strip off a section of sod, mulch heavily, and then do the next chunk since the mulch will cling to bare dirt better. Be sure that before you get started you set in a barrier of some sort between the lawn and the slope so that the two can't grow into each other. It can be an edging buried to ground level or a trench that is V shaped in cross section to keep the roots from crossing.

Do you or your kids use the slope as a way to get down to the lower level of yard? If so, plan either steps or a path.

A couple of other plant suggestions for sun: I have a steep slope in sun that I have planted with a combination of old-fashion orange daylilies, and Centaurea dealbata, both of which will spread and are about a foot tall when not blooming. In June it's mass of screaming magenta Centaurea, and in July the daylilies bloom. Butterflies and hummingbirds like both, and the seeds feed the finches. I'm in the process of trying out shrubs to add that will withstand both the voles and the aggressive plants already there, but it may just stay the way it is with the two tall ground covers mingling.

Fragrant sumac and some ornamental sumacs are all the rage now as a shrub, you might investigate those. They look rather pathetic in the winter though. Pretty hardy though. Rhododendrons are classic shrubs for hillsides too, if deer aren't a problem. I work at an arboretum that was built on an old gravel pit, with steep hillsides. I'm always experimenting with trying to make them look nice. Mulch does creep, darn it! That's why you'll probably want to do this in sections and use something to hold the soil in while the plants get established, like some boards or railroad ties held down with rods or stakes.

I've got Rhodadendrum and a huge sumac I'm my neighbors yard. Good to know its a popular trend.

I agree about the cardboard on the hill; easy but probably won't cling. I prob need to kill the grass and next season plant.

My kids are rarely up there and two sets of steps. It's actually just too much yard for us. A weeping cherry or dogwood would be so lovely up there.

Are you in snow country? If so, consider sledding on that great hill! Just leave a course planted with perennials that die down in winter. Don't want to mow down rhododendrons!

If you kill with glyphosate, you can plant soon after. Just wait for the grass to die, mow the remains as short as possible, plant, and mulch heavily. The glyphosate is only active for transfer until it dries, and then starts breaking down soon after. To my mind this is one of its advantages over other more long-lived herbicides.

You could even tack down a big black tarp for a few weeks to kill a lot of the grass. Does glyphosate kill grass? I didn't think it did, I thought it was just a broad-leaved plant killer. I used to spray it on a tiny patch of lawn to control weeds. It didn't kill the grass. There are grass killer chemicals out there but I'm not sure how long that chemical persists, don't know anything about it.

What is the best method for applying the grass killer? Those large sprayers? I have one but honestly, I couldn't make it work (it was from a friend). I could do the tarp thing, but it would look SO ugly during our really pretty season outside. It could be something I do this fall to plant early next spring.

We do have snow- my kids so sled on it occasionally. :)

Glyphosate DOES KILL grass. It is the most commonly used grass killer of all.

I know I'm more into yardwork than the average person, but I don't know how anyone who owns a home could settle for less than a backpack sprayer, as the carry type rip your arm out your shoulder socket after one trip around the yard. While I'm not recommending it as the greatest sprayer, the back-pack available from Harbor Freight (if one has that store close to them) is cheap and will work as a get-me-by for a decent period of time. If one wants a decent back-pack sprayer that will last, they should get one in the $80 - $120 range. Always, I find that changing the spray tip from round to "fan" helps immensely in spraying in a more controlled, precise fashion.

Edited to add: I did a little sleuth work because this question was bugging me. It is sort of off topic. It wasn't glyphosate (trade name "Roundup") that didn't kill my grass, it was another product made by Bayer, https://www.bayeradvanced.com/articles/understanding-weed-killers, ingredients were "2.63% Isoxaben; 4.73% 2,4-D dimethylamine salt; 1.10% Mecoprop-p potassium salt; 0.52% Dicamba, potassium salt." Wrong large multi-national chemical company, wrong chemicals! A cautionary tale, you have to use your chemicals correctly to get the desired results!! Some work only at certain stages in the growth of the weeds or grass. Also, they all break down at different rates which will factor into how soon after application you can plant something.

I second the sprayer recommendation. That will help you maintain the area over time as you shift from grass to groundcovers and whatever else you want there.

"Such as water and replication coordinator took the canvas cover for it" ... Is this hipster code lingo? Whatever does it mean ...??