How much sun and how wet is the soil? Your main concern should be erosion control. My area is dry and sunny, so I have pink muhly grass and new jersey tea.

https://www.gurneys.com/product/pink-muhly-grass?p=0515548&pid=90027&gclid=CjwKCAiA-f78BRBbEiwATKRRBPi1wQSGzJQQhlkAocuZwaGK3TMGDBmJ-qS6SPixzrtLLF_rqOCLTBoCziEQAvD_BwE

https://prairielegacyinc.com/shop/shrubs-trees/ceanothus-americanus-var-pitcheri-new-jersey-tea/



More ideas
https://www.plantnovanatives.org/erosion-control

We inherited a raised bed that implanted with wildflower seeds two seasons ago. It was the SE US mix from American meadows. The first year we got a lot of annuals, and I was confused why some of the flowers didn’t bloom until I realized they were biannual. The perennials did come up and bloom as well though not as strongly as the annuals. The second year, it was almost all perennials / biannual — the annuals hadn’t self seeded, and I hadn’t added any additional seed. But wow, was it full of flowers.

Slopes are hard because your flowers will tend to fall over down the slope. I would recommend shorter ones rather than taller ones. I would also recommend not doing what I did and buying a crazy mix of seeds and instead just sticking to a handful of varieties. In the first year you’ll get a lot of weeds (with fewer the following year), and when you have too many varieties of flowers, it's impossible to tell what’s supposed to be there and what's not.

Also, do you have room for some compact bushes at the bottom of the slop? They could keep the flowers from flopping over completely and also help control erosion.

Good luck OP
Just to add - growing wildflowers from seeds might be tricky, I suggest potted plants or bare-rooted plugs than seeds

OP here. Thanks for all the advice and feedback. We don't have an HOA and the mulchy, weedy patch of yard that our neighbors currently view will be improved with pretty much anything we do, I think. Will try some things and see what happens.

I bought some wildflower seed mixes from the Urban Farmer this year and planted them in spring. I had low expectations, but we ended up having terrific results. I think the "children's garden" mix did the best of the ones we tried, including the one designed for this region. www.ufseeds.com

This is the information you’re looking for

http://www.mdturfcouncil.org/resources/Documents/TT%20Bulletins/TT-70%20Establishing%20And%20Maintaining%20Ornamental%20Flower%20Meadows%20For%20Low%20Maintenance%20Sites.pdf" target="_new" rel="nofollow"> http://www.mdturfcouncil.org/resources/Documents/TT%20Bulletins/TT-70%20Establishing%20And%20Maintaining%20Ornamental%20Flower%20Meadows%20For%20Low%20Maintenance%20Sites.pdf

But as others have said, it’s a lot harder than you might think. Weeds are relentless, and if deer can get to the site you might as well not bother trying.

Wildflowers=weeds

The slope is my biggest concern with what you are describing. Also I am not in the DMV. I put a bunch of wildflower seeds in my front yard that has a slight slope and that we had previously covered in mulch. I got a lot of wildflowers. It does look straggly, and it will take a few years of doing it for them to get thick. One of my neighbors has a gorgeous bed and she told me this is what she had done a few years ago, so it will just take time.

I am in CA where everything grows, and don't live where there is a HOA which are important points for me to add. My neighbors may not like the straggle but they aren't going to say anything about it.

Agree with PP re meadow
Since your whole area is mulched you can plant some perennials in a portion of it with minimal effort.
Then wait and see how you like them over the next summer before deciding what to do next.
http://chesapeakenatives.org/plant-sales/ and https://bluewaterbaltimore.org/herring-run-nursery/ still open for business.

Honestly, establishing a real wildflower meadow is among the hardest gardening pursuits. And we don’t even have the right climate for it. And a slope is even harder. Whatever you’re picturing in your head ain’t going to happen from scattering some seeds.

You could plant rudbeckia and echinacea, which are native and very easy to grow perennials. There are a bunch of native plant nurseries locally that will sell you those and others. They will look spectacular in bloom, but they won’t be a “meadow.” And when they’re not in bloom, depending on where you live, your neighbors might not be happy with you.

If you really want to do annuals from seed, cosmos are pretty easy and so are zinnias. Basically you’d revert to mulch all winter. But on a slope they will require some tending.

If you’re new to gardening as well as to this house, do some small scale experiments next year so you’ll know more what to expect.

We have a pretty steeply sloped hill on one side of our yard that goes down to the road. It's been mulched for decades (we're new owners). I think that deeply rooted wildflowers would make a for far nicer yard, but not sure what will work best in this area. I did read that it seems sowing seed after the first frost is the right way to go, so I think we can still do this now for spring growth. Thanks!