I can’t stop trying to figure out the last deck post in the top pic…anyway, terracing may be your only option.

tj

You should work with what you have and embrace the hilliness and the rockiness. Otherwise you're in for a costly, losing battle.

I would invest in some rock (not round river rock, but something that looks like what you have in the ground) and construct terraces. Fill them with shrubs that will keep the slope in place and soak up the water (e.g hydrangeas). Shrubs and spring bulbs are a good low-maintenance option.

You already have a deck, so you don't need another sitting area. Focus on making it nice to look at from the deck.

If you give us your geographic location, folks can suggest specific plants.

Im not the PO but @JoJo (Nevada 9A) what kind of rocks are those and can you identify at least some of the plants? i need to post my slope which is very like that one. im zone 7/7a Shenandoah Valley VA. thank you! c

Terraces seem like a good idea, and it would be easy to fence it. Hopefully it’s squishy there because water is draining away from your house and not pooling in the area, might want to have someone take a look at it. A bit of professional grading when you do your terraces could help move some of that water away.

Trailrunner, that's not my yard, so I don't know what kind of rocks they are. I would recommend visiting you local stone and mulch yard to see what they have. Something excavated locally will always be a good match to your landscape.

As far as the plants, I can only recognize catmint (nepeta), hydrangeas, and lavender (?) -- the rest is kind of blurry. I hope folks with better eyes will chime in!

Always always always start by figuring out where in the world you are. There are a lot of 'solutions' that may work fine for the person posting the 'solution', but aren't the right path for someone in a different climate/zone/continent/planet. For example, retaining walls are always expensive, and often a completely unnecessary approach.

BTW, JoJo, I think I see some roses in there.

@JoJo (Nevada 9A) and @mad_gallica (z5 Eastern NY) thank you! I will get pics together tomorrow and make a separate post. c

I’m in NJ zone 6b! The 4th picture is the view from the upper deck. I walk through that area to get to the garage/side of the house so it still needs to be accessible.

You can incorporate some stairs into the slope, safer than a wet stepping stone pathway.

More usable generally means level. Make one terrace the length of the house as wide as the second story deck and the steps off the bottom deck. Make steps down to the garage/driveway level. This wide terrace will be enough for the walkway around the house and be the raised bed for planting. You can do more planting on the slope below the terrace if so desired.

My sister in law gardens in South Orange, NJ. I mention this because she has voracious, illiterate deer. They browse plants that are commonly listed as deer resistant. Fencing them out ... it takes more than a six foot fence to keep hungry deer out of your yard. So after you build the terraces, landscape them with highly deer resistant plants only.

Yes the deer just ate all the leaves off my new dogwood tree as well as my hostas and other plants out front. There are lots of other critters so I have to plan for exclusion and deterrents as well.

If I decide to terrace, would it still make sense to cover everything with cardboard and add new soil? I would still have to get rid of the weeds. And I’m not going all the way down the slope. Still trying to figure out where to start.

Start by realizing that Central Park has received almost 10" of rain so far in July. So if you don't have water in your lower level you are ahead of the game. You have good grading near the house, and you don't want to mess that up.

Do you want some kind of plants next to the house? Shrubbery? Perennials? Which way does the house face? This is help us understand how much sun the area gets. From the pictures, it doesn't look like it gets a lot. Do you want the stepping stone path to go through a planted area, or just on one side?

Bringing in new dirt is often a bad idea for several reasons.Among them are it will alter the grading, and you don't know what it is, or where it came from.

Growing hostas in deer country guarantees heartbreak. Same with yews.