Nope, judging by the slope in the photo it is not going to be as simple as bringing in some soil to fill 'the dip'.

This is a case where a landscape designer and or landscape contractor will be of value.

There are several factors that require attention and a seasoned professional who is familiar with your local codes, soil conditions, drainiage, retainment construction, and climate will prove to be valuable.

fpmom, one would need to know the elevation of the terminating end of "the dip" in order to know what can be done with it. If your property line there is much lower, then you cannot just raise the grade without first installing a retaining wall (much $$$.) Surely, your yard can be made usable without major grade change ...? It's probably a better idea to come up with a plan that works with the grade you already have (or close to it) instead of spending much money on something that will not give you a $ return. The good news is that neither dogs nor children care about slope insofar as their play area is concerned.

do you have more pics of your house? especially the back yard's?

this is one of my ideas, hope you like it.

The slope directs water away from your home, which is a good thing. If you want flat, a retaining wall would be required, which is a job for licensed professionals and not cheap. Flattening out a small section in the back for a play area rather than the whole property would be more economical. Keep in mind that changing grade/drainage needs professional expertise to avoid damage to your foundation. Your municipality might also require permits, etc.

Oh my gosh, a slope IS a play structure! And as someone already pointed out, slopes make much more interesting gardens. It would help to know where your property line is, and this is probably not a DIY job, as significant grade changes may have consequences not only for your property, but for neighboring properties as well.

Are you really wiling to give up the natural light from those basement windows?

As for a fence, check with some local fencing companies to see how they have dealt with similar situations. We have one in our area that keeps a scrapbook of past installations in their show room - it's full of ideas.

With respect to the soil and improving it, if there is moss the soil is most likely compacted and acidic. Even if you are going to raise the grade, that situation should be addressed, as many plants have roots that want to go much deeper than you might think.

Sorry to "rain on your parade", but I'm stuck with a flat yard ... OK, there's just a little hillock at the base of the drive, but it's not much ... and would be thrilled with such a site! Just want to get you thinking about some other (and more interesting) options, as well as some possible consequences you might not have considered yet.

My idea is to create a new area where could put play structure, also could be a little patio⦠either using steps or raising the grade a little bit will work. I do not suggest filling the whole area to flat, but using steps to create a level flat hardscape. Then growing plants to softer the boundary and connects to the nature slops gradually. I think it would be nice.

Something tells me the OP isn't buying our suggestions. I'm sure fpmom has plenty of reasons. I'd be interested in hearing them.
Mike

Here is a link that might be useful: My garden pics

I loved your pictures Mike. Thank you.

Mike,
Your yard is gorgeous! I would love to have mine look like that! Well not mountains lol. If you have any ideas for me see my 'planting ideas' post. I am quite open to suggestions!

Thank you emmarene and Messymarsy2.
I posted the link to my garden as a way to show some 'credentials' as to what my advice might be worth. Some people post advice and they have very little experience and knowledge. It's hard for the original poster to separate valuable advice from downright wrong advice.
I was a garden designer and landscape contractor for over thirty years here in the hilly Seattle area. I have built many rock walls over that time in doing new construction landscaping and yard makeovers. Everybody has a limited budget, especially right after buying a new house, so I learned how to get the most out of what was available. Rock walls cost a lot of money for the square footage involved and building one, plus backfill, just because you can't live with a slope, doesn't make sense to me.
Yardvaark and the other posters gave good advice and worded it far better than I just did.
Mike.....and I like building rock walls and rock outcroppings.

You can build a play structure right on the slope!..Jjust build one side with shorter support posts and the other with longer posts. The slope can be part of the playhouse design.

I'm sorry about the lack of follow up sooner - I became quite ill after posting thisâ¦
We have been in the house since Jan and did a lot of work over early summer (earliest we could get contractors in) to completely transform the garden
We pretty much had a digger and excavator come in and rip out the crumbling front path, all the bushes at the front of house and all the overgrown rhododendrons down the sideâ¦we then had the contractors/landscapers re-grade the entire yard - evening up the front and then filling in the side with a LOT of new loam and then built up the sidesâ¦also installed a dry well to help deal with the excess water that 'sits' â¦.there is very little slope now and after installing sod and the new beds (we planted all the new beds, plants and trees ourselves) we are pretty happy with the outcomeâ¦still need to put a picket fence up on to the side of the yard to create a 'back yard' and we want to put a deck and patio in back next Spring

A couple more photos...

another photo

another photo

another photo

It looks nice.
You spent a lot of money.
Did you put in a wall on the right side?
Are those matching Japanese weeping maples near the walk going to grow wider?
I hope you are feeling much better.
Mike

Thanks Mike
We spent a decent amount but not as much as it looks - we put money in to the walkway and labour in re-grading but we did a lot ourselves: sourced all the plants, made the beds, planted everything which was a lot given there was nothing left once the excavator came inâ¦
What we didn't realize initially was that the big dip down did go up a little on the border of our neighbors property - the contractors built that side up (on the right) and we have planted a row of 4x4 boxwoods and steeds to make a hedge in time (we will also put up a fence along there in Spring)⦠it worked out quite well because it meant that the middle could be built up by about 3-4 ftâ¦I put down a LOT of mulch (we did the bed and plantings as well as mulch all along there as well) so now the water doesn't build up as much though the area still stays quite wet - I will take a photo of that side for you⦠once the ugly overgrown rhododendrons were removed it really opened up the yard and made it soooo much bigger - a major improvement! It has been money very well spent but doing a lot yourself saves a heap ;)
PS The japanese maples won't grow too big - they are a smaller varietyâ¦. we also planted a flowering dogwood on the left side and a kousa dogwood on the right side of house

This pic is at the back of the house - MORE to plant hopefully this week with the warmer weather(japanese holly and shamrock inkberry)
I am going to get some kind of gravel/peastone delivered this week to fill in the dirt area as a stop gap but this area will eventually become a paved patio
PS We are surrounded by pine trees and those brown things are all the pine needles dropping - a major pet peeve

The back
Adding all the bushes for when the trees lose their leaves and it's bleak back there - needed some evergreens
PS Apologies for sideways photos - don't know how to fix

Mike these are photos of the right side (taken from inside house upstairs) - where the pink mums are is where the rhododendron was

More of the right side

Thank you for returning with completion pictures. I never would have thought it could be possible to fill in that gully. It is lovely now.

I would love to see photos of how you did this, since my yard has similar issues in the back and I have only a small area of usable yard because of it. You don't show any photos of the the property line where the dip was deepest in your first picture. How did you support this fill? Was there already a retaining wall there because of the driveway next door? I can't quite understand what you did.

Sue once we had a good look at things with the landscapers it was pointed out to us that they could build the soil up to the boundary with the neighbors because our neighbors side was a few feet higher than the lowest dipâ¦.the dip show in the pic is not in the middle but maybe two thirds in towards the neighbors sideâ¦this was hard to know when I posted this because of the overgrown rhododendrons partly hiding that side - we did not need a retaining wall because the landscapers built up the neighbors side slightly more then filled in the dip with probably 4 truckloads of loamâ¦.they also built up the front of the property on the right to even it out - built it up by about 2 feet which made a big difference and meant that a retaining wall was not required where the ugly green bush is in front of the house on the right sideâ¦hard to see that in the before photo because the bush was hiding the detail - we initially thought we would need a retaining wall but once the bushes were removed we could see that we could fill in that area (in retrospect I wish I had taken many more 'before' and 'during' shots but once the excavator moved in they worked fast)â¦the yard is not completely flat - it slopes down slightly away from the house for drainage etc â¦our basement is extremely dry
My advice is to get a few different people in and ask if they can 're-grade' your yard to make it more usable⦠I had no idea about this until I had landscapers out for quotes (mainly about re-doing the front path initially) and they all suggested the same thing for the side of the house - removing trees etc and putting in sod after made a huge difference and to be honest things turned out way better than I had expected
PS The driveway next door was dug out so there is a wall there holding up their side of the garden along the boundary

Thank you. I don't think it would work for me because the dip in my yard, the lowest point is on the property line and my neighbor behind me has a row of pine tree planted in it. He has the same issue but was not open to taking down the trees and bringing in some fill to level off the yards. So I would have to confine it to my own yard and probably build a retaining wall the length of the property, which would be quite pricey.