Are you trying to save the junipers?

I probably would sacrifice the junipers. It will be easier to kill the weeds and do the planting if you didn't have to work around the junipers.

I would kill the entire slope using carefully applied herbicides, cut the junipers off at the soil line (do not dig out the roots) and then replant with a quality native mix, covered with an erosion control blanket. The blanket acts as mulch and will hold the seed and soil in place on the slope, until the natives get established.

I would suggest a North American Green product, probably a SC150 Double Net Straw-Coconut Blanket that will degrade over time. Or if the slope is really steep, I would use a North American Green P300 Turf Reinforcement mat, that doesn't degrade over time. Make sure the blankets are installed properly. The blankets aren't that expensive, if you consider you've saved the cost of reseeding that is often necessary on slopes.

I just think it will be very hard to control the weeds and establish natives within the junipers...but if you're willing to tackle the work, you can cut slits in the erosion control blankets to accommodate the junipers.

Here is a link that might be useful: North American Green

Joepye, thanks for your response. I have a few comments and more questions for you.
Part of the reason for trying to save the remaining junipers is sentimental since I recently found out that my late father may have been one of the prior volunteers that put them in. However, due to his prior history as a farm kid, I am also pretty confident that Dad would have told me to not be too sentimental about particular plants or animals and to do whatever needs to be done.
I am (or maybe was) also trying to save the remaining junipers because I do not want the project to get bigger but they might die off from the fungus no matter what I do so I might be following your plan whether I like it or not. The arborist says the fungus will finish off the junipers if they are not sprayed with fungicide a few times a year and I actually believe him since he has gone out of his way in the past to avoid having me waste money. I am told that the junipers have been there for over 20 years so the junipers did serve their purpose for a while. I have used a North American Green erosion control blanket before and it did work for establishing native creeping red fescue on another steep slope even though I am an amateur with such things. I am also thinking of hydroseeding due to the steepness but I don't know what the cost is. The particular "plateau" area is now free from junipers. The remaining junipers are to the sides and below the plateau area. The area below the "plateau" is extremely steep which is another reason why I'm not thrilled with increasing the size of the work area to include where live junipers still are. There are definitely invasive roots in the area which will surely regrow. There must also be a huge seed bank of invasive seeds because the area was let go for a long time before I came around and all I did was cut out the vines, etc. once or twice a year to reduce mass and to remove the bulk of the seeds but certainly not all. There are a few volunteer natives in the area but probably not enough to worry about.
If I use your plan on all or part of the slope should I first do repeated treatment of weeds for one or more seasons before reseeding with natives and blanketing? Do you think the idea of first growing cereal rye makes any sense? It did help as a temporary measure with my other big slope project.

If it were a flat area, I probably would recommend repeated weed kill. Usually three times per growing season, to get the early season, mid season and late season weeds... however being on a slope, I may not do that thorough of a weed kill...I would worry about leaving it un-vegetated for too long. You can follow your instinct on how stable the slope will be without vegetation. Erosive soils, with lots of runoff or not that bad?

The rye makes sense, but I probably would (and usually do) seed annual rye right in with the native mix. No need to seed it twice. Many native seed suppliers will add the rye right into the mix. The rye will grow in quickly to get that cover you want, but it won't be able to out compete the natives in a couple years when they are starting to send up top growth.

And I wanted to add, with respect to hydroseeding, the area is probably too small to be economical for hydroseed, they could shoot that area in about two mintues, not worth loading the machine. If access is an issue, hydroseed is a good idea. And if you can catch the seeder when they are in your area and can piggyback on another project, nearby, with the seed mix that you want, you might be able to get a good deal.

Thanks JoePye.

Good luck with your project. Let us know how it goes...

You may have a problem saving the original junipers, because unlike most shrubs, they have very few secondary buds that will regrow after a hard pruning. You may get a little bonsai action, but they won't regrow like a holly.

Therefore, you may want to watch for offspring before you move in with herbicides. A slower method, like smothering the areas you can with thick newspapers and mulch, might work better if your plan is to grow native shrubs. If you don't do something, well, if you're an invasives veteran, you know. They just keep coming back.

Well-placed stones can help structure the slope and give you places to stand securely. And they're always in season!

Here is a link that might be useful: my website

They did a very good job at leaving some live material on the remaining junipers but the long-term prognosis for the junipers just isn't good from what I have been hearing and seeing. As always, when I fix one problem I discover new problems. Due to limits of time and resources I think I will have to slowly replace the junipers as the attrition gets them. If I was to start completely new and with unlimited resources, I would properly terrace the whole hill but that is not in the cards for now.